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Hot spring hydrochemistry on opposite sides of theRio Grande rift in northern New Mexico and ageochemical connection between Valles Calderaand Ojo CalienteValerie Blomgren

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Recommended CitationBlomgren, Valerie. "Hot spring hydrochemistry on opposite sides of the Rio Grande rift in northern New Mexico and a geochemicalconnection between Valles Caldera and Ojo Caliente." (2016). https://digitalrepository.unm.edu/eps_etds/102

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Valerie Blomgren Candidate Earth and Planetary Department Department This thesis is approved, and it is acceptable in quality and form for publication: Approved by the Thesis Committee: Dr. Laura Crossey, Chairperson Dr. Karl Karlstrom Dr. Tobias Fischer

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Hot spring hydrochemistry on opposite sides of the Rio Grande rift in northern New Mexico

and a geochemical connection between Valles Caldera and Ojo Caliente

by

VALERIE BLOMGREN

B.S. EARTH AND ENVIRONMENTAL SCIENCE, UNIVERSITY OF ILLINOIS AT CHICAGO

THESIS

Submitted in Partial Fulfillment of the

Requirements for the Degree of

Masters of Science Earth and Planetary Science

The University of New Mexico

Albuquerque, New Mexico

July 2016

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Acknowledgments

I would like to thank my committee Dr. Laura Crossey, Dr. Karl Karlstrom and Dr.

Tobias Fischer for their advice and expertise. I would also like to thank Hyunwoo Lee of

the University of New Mexico for helping me collect gas samples, analyzing my samples

and advising me on gas chemistry. I am grateful for the lab facilities and advisement from

Thomas Darrah of the Noble Gas Laboratory of Ohio State University, Tobias Fischer of

the Volcanic Geothermal Fluid Analysis Laboratory at UNM, Mehdi Ali of the chemistry

laboratory at UNM, Yemane Asmerom and Victor Polyak of the Radiogenic Isotope lab

of UNM, and Viorel Atudorei and Laura Berkemper of the Center of Stable Isotope lab at

UNM. I thank Paul Bauer for helpful discussion of springs of the Taos region. I received

additional help in the field from Marisa Repasch, Jared Smith and Chrissy Allen. I am

also grateful for the land owners of La Madera and Ojo Caliente for permission to access

their land. I gratefully acknowledge funding from National Science Foundation (NSF)

EPSCOR award #IIA-1301346 and a research grant from New Mexico Geological

Society which covered cost of analysis.

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Hot spring hydrochemistry on opposite sides of the Rio Grande rift in northern New Mexico and a geochemical connection between Valles Caldera and Ojo Caliente

By

Valerie Blomgren

B.S. Earth and Environmental Science, University of Illinois at Chicago M.S. Earth and Planetary Sciences

ABSTRACT

Warm and hot springs are present on both sides of the northern Rio Grande rift (RGR).

Springs on the western side of the RGR are along faults that extend NE of the Valles

Caldera; springs on the east are along faults near Taos, NM. The Valles Caldera is a

significant feature near our study site because it had major rhyolite eruptions 1.6 and 1.25

Ma, subsequent rhyolite eruptions lasted until 40-60 ka, and the Caldera now hosts an

active magmatically driven geothermal system. The latest volcanism in the Taos Plateau

region, near the eastern springs, was older, ~ 2 Ma. We compare spring chemistries using

a multi-tracer approach from both spring groups as well as from nearby meteoric springs

for comparison. For the western group, we also relate hydrochemistry of western springs

to distance from the Valles Caldera.

The combined multi-tracer results for Ojo Caliente are interpreted in terms of high

CO2 from magmatic sources, high geothermal tracers (Li, B, Na, Cl, Cext, He, Sr), δ13C

values of -3.5 to -6.8‰, deep circulation through radiogenic basement based on 87Sr/86Sr

values of 0.747, and presence of 1.6 to 4.0% mantle derived helium. The eastern springs

multi-tracer results show less geothermal input as shown by lower concentrations of CO2

and geothermal tracers, although they have a similar helium isotopic signature of up to

~4% mantle-derived helium.

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The geothermal tracers at Ojo Caliente hot springs are interpreted to be distal

influences of the Valles geothermal system. Volatiles (CO2 and He) as well as small

volumes of geothermal water are transported ~60 km along the Embudo accommodation

zone and Ojo Caliente fault systems of the Jemez lineament and RGR. These regional

basement fault systems provide conduits for vertical and lateral migration of deep gases

and solutes to rise and mix with meteoric fluids, verified by mantle helium and endogenic

carbon isotopes.

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Table of Contents

Acknowledgments........................................................................................................................... iii

ABSTRACT .................................................................................................................................... iv

List of Figures ................................................................................................................................ vii

List of Tables ................................................................................................................................ viii

1. Introduction and Motivation ........................................................................................................ 1

2. Structural and tectonic settings .................................................................................................... 3

3. Magmatic setting .......................................................................................................................... 5

4. Regional aquifers ......................................................................................................................... 6

5. Significance of travertine ............................................................................................................. 7

6. Sources of CO2 - Carbon isotope calculations ............................................................................. 7

7. Sample collection ......................................................................................................................... 8

8. Analytical methods ...................................................................................................................... 9

9. Multiple Tracers and their uses .................................................................................................. 12

10. Results ...................................................................................................................................... 16

11. Discussion ................................................................................................................................ 21

11.1 Discussion: Comparison of eastern and western spring groups ............................................. 22

11.2. Discussion: Comparison of Valles Caldera to Ojo Caliente ................................................. 24

11.3. Discussion: Local CO2 story among the western spring group ............................................. 27

12. Conclusions .............................................................................................................................. 28

References ...................................................................................................................................... 30

Figure Captions .............................................................................................................................. 45

Figures ........................................................................................................................................... 63

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List of Figures

Figure 1A: Mantle tomographic image at 80 km depth of New Mexico from Schmandt

and Humphreys (2010) ..................................................................................................... 63

Figure 1B: Study Area showing Valles Caldera and springs ............................................ 64

Figure 2: W-E cross of southern San Luis basin of the Rio Grande Rift .......................... 65

Figure 3: Stable isotopes of hydrogen and oxygen ........................................................... 66

Figure 4: Piper diagram of study area springs and Valles Caldera ................................... 67

Figure 5: Cross plots of geothermal-associated trace element concentrations (Li,B,Br,Cl)

........................................................................................................................................... 68

Figure 6: External carbon plot of δ13Cext vs. Cext concentration ....................................... 69

Figure 7: Radiogenic strontium ........................................................................................ 70

Figure 8: Dissolved gases of study area and free gases of the Valles Caldera ................. 71

Figure 9: Trilinear plot of helium isotopes and CO2 ......................................................... 72

Figure 10: RC/RA plotted against distance from the Valles Caldera ................................. 73

Figure 11: CO2/3He plotted against distance from the Valles Caldera ............................. 74

Figure 12: 3He/4He (expressed at RC/RA) vs CO2/He ....................................................... 75

Figure 13: Graph of 3He/4He (expressed at RC/RA) vs CO2/3He ...................................... 76

Figure 14: δ13Cext vs CO2/3He graph ................................................................................. 77

Figure 15: NE-SW Cross section from the Valles Caldera to the western spring group

along the hypothesized Embudo fault zone flow path and schematic drawing of volatile

degassing. .......................................................................................................................... 78

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List of Tables

Table 1: Spring abbreviations, locations and parameters ................................................. 52

Table 2: Trace element concentrations and stable isotopes of hydrogen and oxygen ...... 54

Table 3A: Major ion chemistry ......................................................................................... 55

Table 3B: Major ion in mol/L concentrations................................................................... 56

Table 4: Saturation indexes and CO2 concentrations ........................................................ 57

Table 5: Stable isotopes of carbon .................................................................................... 58

Table 6: Radiogenic strontium .......................................................................................... 59

Table 7: Dissolved gases of springs in the study and free gas of the Valles Caldera ....... 60

Table 8A: Dissolved helium and CO2 in water ................................................................. 61

Table 8B: Dry gas - helium and CO2 data ........................................................................ 62

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1. Introduction and Motivation

Hydrochemical analysis of geothermal waters and gases can provide insight into

their origin and flow pathways. The combination of geochemical tracers can illustrate

geothermal processes, for example in Iceland where gas fractionation was identified

using δ13C in conjunction with CO2/3He ratio (Barry el al., 2014). Helium isotope

analysis in particular is important for geothermal studies because it can detect small

concentrations of mantle-derived helium in mixed geothermal/meteoric fluids (Ballentine

et al., 2002). Faults can be conduits for ascent of deeply derived fluids and mantle

degassing, due to lower pressure along faults (Easley and Morgan, 2013; Fischer and

Chiodini, 2015; Johnson et al., 2013; Karlstrom et al., 2013; Lee et al., 2016; Mailloux et

al., 1999). The role of faults may be especially important in areas of extension, crustal

thinning, high geothermal gradient, and presence of magmatic systems because these

features allow the ascent of geothermal waters (Crossey et al., 2016; Easely et al., 2011;

Karlstrom et al., 2013; Kennedy and van Soest, 2007). Transport of volatiles along faults

has also been shown in non-magmatic geothermal systems in the Morongo basin of

California where higher 3He/4He ratios were measured in springs near active fault zones

(Kulongoski et al., 2005).

Mantle derived volatiles have been sampled in fumaroles and springs of active

and dormant volcanic systems with a magma body (Fischer and Chiodini, 2015). Mantle

volatiles have also been detected in non-magmatic geothermal systems created by

basement faults in areas with radiogenic rocks where deep water convection produces hot

springs (Brugger et al., 2005). Because different types of geothermal systems have

different heat sources, magma body vs. radiogenic rock and deep water flow pathways,

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these systems have different geochemistry; in particular White (1957) found that

hydrothermal systems interacting with a magma body commonly have Na-Cl type water.

This study will focus on two types of geothermal systems, one heated by a dormant

volcanic system (Valles Caldera) and another by a fault related non-magmatic system

(Taos Plateau).

Geothermal systems often involve mixing between epigenic (shallow/meteoric)

waters mixing with endogenic (deeply sourced/ geothermal) fluids derived from below

the regional aquifer. To study fluid mixing of various origins a multi-tracer analysis is

advantageous. Processes studied with multiple tracers are water-rock interaction, fluid

mixing, and gas fractionation (Ballentine et al., 1996, 2002; Darrah et al., 2013; de Moor

et al., 2013; Ray et al., 2009; Gardner et al., 2010). A common theme of the above papers

is the importance of a small volume but geochemically potent “lower world” geothermal

water that mixes with the larger volumes of meteoric “upper world” water in spring

systems.

Previous work in the general study area, northern New Mexico, Colorado and

Arizona, have suggested that helium degassing is taking place preferentially in regions

underlain by low velocity mantle, in tectonically active areas with young faults and

young magmatism; carbonic springs found in these areas with PCO2 much higher than

atmospheric values of 10-3.5 are considered a manifestation of deeply derived fluids

(Easely and Morgan, 2013; Crossey et al., 2006; 2009; Karlstrom et al., 2013; Newell et

al., 2005; 2011). The present study applied these concepts to northern New Mexico

springs with additional geochemical tracers to develop more robust interpretations of the

geothermal systems of the region. The societal impact of this study includes both

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geothermal exploration (e.g. Goff and Janik, 2002) and understanding the influence of

geothermal fluids on water quality (Williams et al., 2013; Johnson et al., 2012; Dai et al.

2014).

We address three questions. 1) Do springs on opposite sides of RGR have

different chemistry? 2) For the western spring group, what is influence of felsic

magmatism, the modern Valles geothermal system, and possible conduits along Embudo

and Ojo Caliente faults? 3) For the eastern spring group, what is the nature of the

endogenic fluid component in the Taos plateau and eastern rift faults?

2. Structural and tectonic settings

The study area is located at the intersection of the Rio Grande rift (RGR) and the

Jemez lineament (Fig. 1A), an area defined by thin crust, slow mantle velocities, and a

young volcanic history (Easely et al., 2011; Goff and Janik, 2002; Schmandt and

Humphreys, 2010). This tectonic setting motivates the study of volatile degassing in

spring waters that may have flowed great distances along RGR and Jemez lineament

faults. The Jemez lineament is a NE-zone of Quaternary volcanos that transects the state

and extends from Arizona, through the Taos Plateau, to the Raton-Clayton volcanic fields

on the Great Plains (Nereson et al., 2013). The southern edge of the Jemez lineament is

also coincident with the Proterozoic Yavapai and Mazatzal suture zone (Magnani et al.,

2004), and is theorized to have been a conduit for magma ascent, figure 1A (Nereson et

al., 2013).

The RGR is a north-trending series of asymmetrical subsiding half grabens

(extensional basins), with a major fault on one side and a hinge on the other (Koning et

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al., 2004). Our study site involves two basins, the San Luis basin to the north and

Espanola basin to the south. The San Luis basin is bordered to the east by the west-

dipping Sangre de Cristo fault that has 7-8 km of displacement (Lipman and Mehnert,

1979) that causes asymmetric subsidence of the basin (Bauer and Kelson, 2004). The

Espanola basin is west-tilted because of greater displacement on the west along the Santa

Clara-Pajarito fault system (Koning et al., 2013).

Between the San Luis and Espanola basins is the Embudo fault, which is a

transfer zone that allows for differential subsidence of the basins (Fig. 1B) (Muehlberger,

1979). At the northern end of the Embudo fault is the Sangre de Cristo fault and the

southern end is the Pajarito fault (Bauer and Kelson, 2004). The Embudo fault is a

dominantly a left lateral strike slip fault with minor north-down dip slip (Bauer and

Kelson, 2004) (Fig. 1B). At larger scale, this fault system also provides a surface

expression of the Jemez lineament (Muehlberger 1979) (Fig.1B).

Within the east-central part of the San Luis basin is the N-S trending Taos Graben

(Fig. 1B) that is bordered to the east by the Sangre de Cristo fault and on the west by the

buried east-dipping Gorge fault (Bauer and Kelson, 2004). Grauch and Keller (2004)

imaged the Gorge fault 17 km north of Questa, NM and as far south as Taos. The Gorge

fault deepens to the south of Taos and is inferred to continue south intersecting with the

Embudo fault (Grauch and Keller, 2004). The Taos Graben was imaged with gravity data

in Cordell (1978). The Gorge fault has the majority of the springs of eastern spring group:

Bear Crossing, Manby and Black Rock. Bear Crossing spring is located at the

intersection of the Gorge and Red River faults, which is the spring located the furthest

north near Questa, NM, (Bauer and Johnson, 2012). The final spring of the eastern spring

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group is Ponce de Leon located on the Picuris-Pecos fault. The Picuris-Pecos fault first

showed movement in the Proterozoic, later it was reactivated during the Laramide

orogeny (Miller, 1963) and most recently in the Neogene it began extensional movement

as a normal rift fault to the Santa Fe range (Bauer and Kelson, 2004).

On the western side of the RGR, the Embudo fault intersects the northwest-

dipping (Koning et al., 2011) Ojo Caliente fault zone, which hosts the western springs of

this study, Ojo Caliente, La Madera and Statue (Fig. 1B). The hot spring waters of Ojo

Caliente discharge at the intersection of Precambrian northeast-trending shear zone with a

normal east-dipping Pliocene fault; these faults may be reactivated Precambrian

structures (Vuataz et al., 1984). An electrically conductive zone was imaged below the

Rio Ojo Caliente Valley at 10 m below the hot springs, this zone deepens to the north and

south, and dissipates 1 km to the north and 2 km to the south of the hot springs (Vuataz et

al., 1984). It has been interpreted that thermal plume waters rose along the Pliocene

Valley fault because thermal waters were only located near the ground surface along this

fault (Vuataz et al., 1984).

3. Magmatic setting

The volcanic system near the western part of the study area is the Jemez volcanic

field and in the east is the Taos Plateau volcanic field. The Jemez volcanic system

developed over the last 13 Ma (Gardner and Goff, 1984), and Taos Plateau volcanism

ranges from 1-6 Ma (Lipman and Mehnert, 1979; Appelt, 1998). Compositions in the

Taos Plateau are dominantly mafic to intermediate compositions (basalt, andesite and

dacite) though rhyolitic volcanos are also found (Johnson and Bauer, 2012). In the Jemez

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Mountains explosive rhyolitic caldera eruptions occurred 1.6 and 1.2 Ma (Spell et al.,

1996). Both volcanic areas are located above a zone of low mantle velocity along the

Jemez lineament (Fig. 1A); these low mantle velocities are interpreted as areas containing

a small percentage of partial melt (Schmandt and Humphreys, 2010).

Among the most recent volcanism along the Jemez lineament is the Jemez

volcanic complex that still hosts a geothermal system (Goff and Gardner, 1994). Studies

have shown that a plume of geothermal water flows laterally from the Valles Caldera

southwest along the Jemez fault (Fig. 1B) (Goff and Gardner, 1994). The dissolved gases

and solutes of this plume have been characterized in Goff and Janik (2002), Vuatez et al.

(1988) and Truesdell and Janik (1986). This study and McGibbon (2015) proposed that

the range of influence of this plume extend farther to the southwest than established

models.

4. Regional aquifers

The Santa Fe Group is the main aquifer of the study area (Drakos et al. 2004); it

was deposited in the early Miocene to about 1 Ma. The oldest layer of the Santa Fe Group

is the Tesuque Formation composed of the older Chama El Rito member, interbedded

conglomerate and sandstone, and the younger Ojo Caliente Member, fine to very fine,

well sorted eolian sandstone. The next youngest layer is the Chamita Formation, a

moderate to poorly sorted sandstone. The aquifer on the western side of the RGR is

mainly composed of the Ojo Caliente member and the Chamita Formation (Koning et al.,

2011). The youngest layer of the Santa Fe Group is the Servilleta Formation, which has

sediment interbedded with basalt flows (Drakos et al., 2004). The shallow aquifer of the

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Taos Plateau is mainly in the sediment layers, though the basalt flows are heavily

fractured and therefore are also part of the regional aquifer (Johnson and Bauer, 2012).

5. Significance of travertine

Travertine is found in the study area and signifies a connection among spring

water and a significant concentration or reservoir of CO2 because one mol of CaCO3

depositing as travertine requires an additional mol of degassing CO2 (Chafetz and Folk,

1984; Crossey et al., 2006). Crossey et al. (2009) and Priewisch et al. (2014) argued that

travertine deposition is facilitated by a source of CO2 from a deep (magmatic) origin

causing fluids to become corrosive, which then dissolves limestone, increasing the

concentration of Ca and HCO3 ions in solution (Crossey et al., 2006). The carbonate

species that become dissolved in water are pH dependent, neutral waters have dominantly

HCO3 (Drever, 2007), therefore this study will focus on chemical equations using HCO3.

The chemical equations describing travertine deposition are shown in the mass balances

below: 1) dissolution of limestone due to corrosive fluids with external CO2 (Cext) and 2)

the deposition of travertine due to CO2 degassing.

(1) external CO2(g) + H2O + CaCO3(limestone) → Ca2+

(aq) + 2HCO3-(aq)

(2) Ca2+

(aq) + 2HCO3-(aq) → CO2(g) ↑ + H2O + CaCO3(travertine)

(Crossey et al., 2006)

6. Sources of CO2 - Carbon isotope calculations

Quantifying the amount of carbon from different reservoirs using water chemistry

was developed by Fontes and Garnier (1979), further explained in Chiodini et al. (2004)

and modified in Crossey et al. (2009). The three sources of C are from the dissolution of

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carbonates (Ccarb), organic sources such as soil and plant degassing (Corg), and endogenic

sources such as magmas and CO2 from geothermal fluids (Cendo). These sources of carbon

contribute to the total DIC (H2CO3, HCO3, CO3).

The total dissolved inorganic carbon (DIC) is modeled with PHREEQC using

major ion chemistry data and pH (Parkhurst, 1995). SO4 activity is subtracted from the

concentration of Ca and Mg (in mol/L) to correct for any Ca (and Mg) derived from

gypsum (and other sulfates) (Table 3B). Then Ccarb is calculated by adding the

concentration (in mol/L) of remaining Ca and Mg as the molar equivalent of CO2

dissolved from limestone and dolomite. This results in a minimum estimation of the

carbon derived from dissolution of carbonates (and sulfates), termed Ccarb. The Ccarb

calculation is shown in the following mass balance: Ccarb = Ca + Mg - SO4. Ccarb is then

subtracted from the total DIC to derive external carbon (Cext = DIC – Ccarb). Cext is then

resolved into model endmembers Corg and Cendo using stable isotopes. This involves

adjusting the measured carbon isotope value to “remove” the proportion due to Ccarb

which is assigned a value of δ13C= 0 - 1 ‰ typical of the marine carbonates in the aquifer

(Sharp, 2007). This study used 0‰ because Pennsylvania Madera Limestone is common

in northern New Mexico (Crossey et al., 2011). This correction results in the carbon

isotope value of the external carbon shown in the equation below:

δ13Cext = ((δ13CDIC * DIC) – (δ13Ccarb * Ccarb)) / Cext.

7. Sample collection

Spring water samples were measured in the field for temperature, pH, and

conductivity. Samples were filtered and acidified for cation analysis and stored in HDPE

9

bottles, a second bottle, not filtered or acidified, was collected for anions and stable

isotopes. Gas samples were collected in a Giggenbach bottle by inserting a metal hollow

pole into the spring opening with plastic tubing connecting the pole to the Giggenbach

bottle. The Ojo Caliente spring samples were not collected in a Giggenbach bottle, rather

in a 12 mL glass vial with a rubber seal; gas collection was done by filling the vial with

spring water and then displacing the spring water with gas bubbles, this method was

described by Cartwright et al. (2002). A subset of the samples were also collected in

copper tubes and analyzed for noble gas isotopes. The copper tube setup started with

connecting plastic tubing on both ends, then flushing spring water through the copper

tube before clamping the plastic tubing. The copper tubes were then cold-sealed on both

ends with refrigeration clamps; the same method was used in Newell et al. (2005) and

Griesshaber et al. (1992).

8. Analytical methods

Stable isotopes of hydrogen and oxygen were analyzed using a Picarro WS-

CRDS-based analyzer in the Center of Stable Isotope research at the University of New

Mexico (UNM). The Picarro has an evaporator system that is able to analyze liquid

water; the three isotopologues of water measured were H218O, H2

16O and HD 16O as

described in Gupta et al. (2009).

Major ion and trace element chemistry was analyzed in the Analytical Laboratory

of the Earth and Planetary department of UNM. Alkalinity was determined by titration

with sulfuric acid, anions were analyzed using an ion chromatographer EPA Method

300.1, Revision 1.0, (Hautman and Munch, 1997), and cations were analyzed with an

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inductively coupled plasma EPA Method 200.7, Revision 4.4, (Martin, et al., 1994). PCO2

and CO2 saturation index were modeled using PHREEQC from the USGS (Parkhurst,

1995).

Gas analysis of He, H2, Ar, N2, O2, CH4, CO was analyzed by using both a Gow-

Mac series G-M 816 Gas Chromatograph (GC) and a Pfeiffer Quadrupole Mass

Spectrometer (QMS) in the Volcanic Geothermal Fluid Analysis Laboratory at UNM.

The relative abundances of CO2, CH4, H2, Ar + O2, N2 and CO were measured with the

GC using He as the carrier gas, and the relative abundance of He, Ar, O2 and N2 were

measured in the QMS (Lee et al., 2016). The samples were connected to the GC and

QMS with high vacuum lines that were designed to trap water in containers frozen with

liquid nitrogen (Hilton, 1996).

Dissolved inorganic carbon (DIC), sum of the three forms of carbonate (H2CO3 +

HCO3 + CO3), was modeled with PHREEQC from the USGS (Parkhurst, 1995) with

major ion chemistry and pH. Carbon isotopes were analyzed from either water collected

in a HDPE bottle or copper tube, the method used for each sample is specified in table 5.

The carbon isotopes measured from the HDPE bottle were analyzed in the Center of

Stable Isotope research at UNM using the Finnigan Delta Plus isotope ratio mass

spectrometer with a Finnigan MAT GASBENCH 2. The procedure starts with adding the

water sample to a vial at vacuum with a syringe, then adding phosphoric acid to cause a

reaction with the water producing CO2, the CO2 is then carried to the mass spectrometer

with helium as the carrier gas (Torres et al., 2005). Carbon isotopes measured from a

water sample from a copper tube was analyzed in the Noble Gas Chemistry Laboratory of

11

the Department of Earth and Environmental Sciences at the University of Rochester, NY

following methods from Shaw et al. (2003).

Strontium isotope analysis was done in the Radiogenic Isotope laboratory of

UNM. Strontium was extracted from the water sample in a polypropylene column with Sr

resin (product number LOT SRA 121517) described by De Muynck et al. (2009). The

first step in strontium analysis was preparing the column. This started with adding Sr

resin to the column, then rinsing the Sr resin with 3N HNO3 to remove matrix elements,

for example Ca and Rb (De Muynck et al., 2009), then 18 MΩ H2O was added to the

column to remove Sr to ensure there were no other sources of Sr. After the column was

prepared, the spring water sample was added and rinsed with 3N HNO3 to remove matrix

elements. At this point, the Sr from the spring water sample was ready to be collected. Sr

was drained from the column by adding 18 MΩ H2O and collected into a vial. The vial

was then heated on a hot plate to evaporate the water leaving behind the Sr. The dried Sr

was then dissolved with 3%HNO3, producing the solution used in the ThermoFinnigan

Neptune multiple collector ICP-MS to measure the 87Sr/86Sr ratio (De Muynck et al.,

2009; Ma et al., 2013).

Total helium concentration and the isotopic ratio 3He/4He were analyzed in the

Noble Gas Laboratory at Ohio State University, Noble Gas Chemistry Laboratory of the

Department of Earth and Environmental Sciences at the University of Rochester, NY and

The Fluids and Volatiles Laboratory at Scripps Institution of Oceanography using a noble

gas isotope ratio mass spectrometer and electrostatic analyzer. Analytical techniques

described in Darrah et al. (2014), Hilton (1996), Hunt et al. (2012) and Poreda and Farley

(1992b).

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9. Multiple Tracers and their uses

This study used multiple tracer analysis which applied two and three end member

mixing models to explain variable hydrochemistry and to resolve the character of deep

end member components (Crossey et al., 2009). The goal of multiple tracer analysis is to

identify mixing trends in chemical plots that extend away from known meteoric values,

allowing us to empirically approximate endogenic end members. Our conclusions are

more robust when several tracers reveal similar mixing trends.

The stable isotopes of hydrogen and oxygen can be used to identify evaporation

and water-rock interaction based on trends relative to the Global Meteoric Water Line

(GMWL) (Sharp, 2007). The GMWL shows a near linear relationship of δD to δ 18O of

meteoric water (glaciers, ocean, river and lakes) from around the world (Friedman, 1953).

The GMWL slope is 8, whereas an evaporation trend has a slope ranging from 4 to 6

depending on humidity (Sharp, 2007). Water-rock interaction mainly changes oxygen

isotopes because there is little hydrogen in rocks; as water equilibrates with heavy

oxygen in rocks the oxygen isotope ratio in water becomes enriched in 18O (heavier)

(Sharp, 2007). This is shown as a horizontal departure from the global meteoric water

line (GMWL).

Major ion chemistry is presented in a Piper diagram (Drever, 1997), which

displays cations in the lower left triangle and the anions in the lower right triangle, the

ions are then projected into the parallelogram. Piper diagrams visually show how

different waters relate and are most useful in identifying water-rock interactions and fluid

mixing (Piper, 1944).

13

Conservative elements were used in this study to infer water origins. Chloride and

bromide are both conservative and are not as affected by oxidation and reduction

reactions than non-conservative elements, they also behave similarly when adsorbing to

soils therefore the relative concentrations do not vary considerably (Whittemore, 1995).

The increase of the Cl/Br ratio reflects greater salinization due to increasing Cl (Hogan et

al., 2007). Li and B were also used in this study because they may be related to a thermal

source (Evans et al., 2006). Geothermal reservoirs with unique elemental ratios that do

not equilibrate in low temperature water can be indicators of a geothermal component in

springs, elemental ratios commonly used are B/Cl, Br/Cl and Li/Cl (White et al., 1984).

Gas data presented on a trilinear diagram of Ar-N2-He, established by Giggenbach

et al. (1992), distinguishes among tectonic settings (rift and arc volcanic settings) and

fluid sources (atmosphere and mantle). Gases enriched in N2 may have been influenced

by organic rich sediment (Jenden et al., 1988) or subduction magmatism (Giggenbach et

al., 1992). Gases originating from deep crustal and mantle sources plot near the He apex

(Marty, 1994); it is not possible to distinguish among gases from the mantle or old crust

on the Ar-N2-He figure because both sources have high He (Hilton et al., 2002). CH4 was

also studied because abiotic CH4 may be sourced from juvenile carbon from the mantle or

high temperature synthesis reactions of CO2 and H2 (Welhan, 1988).

PCO2, modeled with PHREEQC (Parkhurst, 1995), expresses saturation of Ca,

HCO3 and CO2. If PCO2 is higher than atmospheric levels of PCO2, 10-3.5, more CO2 is

dissolved in water than water equilibrated with the atmosphere and is an indicator of how

much CO2 will degas at a spring opening (Drever, 1997).

14

Carbon isotope analysis distinguishes among three sources of dissolved inorganic

carbon (DIC): dissolved components of carbonates within an aquifer system (Ccarb),

organic volatiles from soil gas or plant respiration (Corg), and endogenic sources such as

magmatic degassing or CO2 from rising geothermal fluids from deep crust or mantle

(Cendo) (Chiodini et al., 2004). The specifics on calculating the types of carbon is under

the above section 6 “Sources of CO2 – Carbon isotope calculation.” Chiodini et al. (2004)

expanded upon carbon isotope studies by creating probability plots of carbon isotopes

and concentrations (with dissolved carbonate species removed) to show bimodal

distributions of two mixing populations, 1) purely organic sources and 2) a mixture of

organic and deep sources; he also found that the locations with the greatest probability of

deep carbon were associated with seismic activity.

Radiogenic strontium was analyzed in our study because it reflects water-rock

interaction along deep flow pathways through Precambrian granite and other rocks

(Faure, 1977). For mixing models, both the radiogenic isotopic ratio and [Sr] are

measured. Rocks gain 87Sr over time from the β-minus decay of 87Rb. Rubidium can

substitute for potassium in crystal minerals such as K-feldspars (Faure, 1977). An

example of highly radiogenic basement rock near our study is the granitic Precambrian

basement that is generally similar in age and composition to basement from Rocky

Mountain National Park in Colorado with an average value of 0.740 from four samples in

Clow et al. (1977). In contrast, Paleozoic marine carbonates in New Mexico typically

have 87Sr/86Sr ratio of 0.709 (Crossey et al, 2006). Strontium concentration depends on

strontium availability and water-rock interaction, the latter being temperature and time

dependent (Hagedorn and Whittier, 2014).

15

The final tracers are helium isotopes. The mantle has retained significant amount

of 3He compared to the crust, because radioactive decay processes in the crust produce

significant amounts of 4He that lowers the 3He/4He ratio over time (Ballentine et al.,

2002). Reworking of the crust has also caused most of the 3He in the crust to degas since

earth formation compared to the mantle (Newell et al., 2005). The helium present in the

crust is mainly 4He from alpha decay, for example 234U to 230Th, therefore fluids flowing

through the crust become diluted by crustal helium lowering the ratio of 3He/4He (Marty

et al., 1989; Ballentine et al., 2002). Fluids with less crustal influence have higher

3He/4He ratios. The fluids emanating from mid ocean ridges have values of 8 ± 1 RA

(Poreda et al., 1992a) and sources with no mantle input (i.e. in cratons) are below 0.02 RA

(Andrews, 1985). It is accepted that values of > 0.1 RA in non-airlike fluids indicates a

significant mantle derived volatile component (Ballentine et al., 2002).

Helium isotopes are reported as the term RC/RA (Ballentine et al., 2002). The

measured 3He/4He ratio is divided by the 3He/4He ratio of air, 1.384x10-6 (Clarke et al,

1976), and is expressed as the term R/RA. R/RA is then corrected for air contamination

(Porcelli et al, 2002; Hilton, 1996), determined by the He/Ne ratio. The ratios of He and

Ne can vary because they have different solubility in water (Marty et al., 1989), though

commonly the air component is corrected by using the X factor, which is the air-

normalized He/Ne ratio, X, multiplied by the ratio of the Bunsen solubility coefficient of

Ne to He at 15°C (Hilton, 1996).

The CO2/3He ratio is commonly studied because this ratio is well defined for

MORB and different values among spring locations reflect geothermal processes. He and

CO2 behave differently in water because He is less soluble, therefore CO2 is more

16

involved in water chemistry (Marty et al., 1989). Solubility is based on Henry’s constants

(Nordstrom and Munoz, 1985). In the early stages of degassing, as mineral waters travel

towards the earth surface, He preferentially goes into the gas phase whereas CO2 stays

dissolved in water (Marty et al., 1989), therefore CO2 is more likely to be transported in

water from a volcanic center, explaining possible gas fractionation. Differences in the

CO2/3He ratio could also be explained by He and/or CO2 traveling in a gas phase rather

than fluid. Sano et al. (1988) discussed transport of gases along faults, and the phases in

which gases are transported. In a study near Mount Mihara in Japan, Sano et al. (1988)

measured how long it took for the concentration of magmatic gases to increase in water

wells after an eruption. The rates of gas transport post eruption were similar to the rate of

water transport through sediment in a rift or coastal setting, rather than crystalline

igneous rock of the region. Sano et al. (1988) concluded that gas transported at high rates

can be explained by magmatic fluids flowing faster during eruptions or that magmatic

gases can be transported in a gas phase rather than fluid.

10. Results

Table 1 lists field parameters. The western springs are more acidic and have

higher conductivity than the eastern springs. pH at Ojo Caliente pH was 6.63 and at La

Madera and Statue springs were 6.02 and 6.34. Conductivity at Ojo Caliente was 4240 µS

and the range at La Madera and Statue springs were 1250 to 1610 µS. The highest

temperature at Ojo Caliente was 53.2°C and La Madera and Statue were 26.1 to 28.5°C.

Springs on the eastern side had a pH range of 7.0 to 8.6, conductivity ranged from 232 to

830 µS and temperature ranged from 16.8 to 39.1°C.

17

Figure 3 shows the stable isotope data of oxygen and hydrogen. Springs from both

the western and the eastern side of the RGR plot to the left of the GMWL with the

exception of the Ojo Caliente springs which plot on the GMWL and to the right of the

GMWL. Also plotted in figure 3 are regional meteoric waters (blue symbols) which

include rivers flowing down from the Sangre de Cristo Mountains toward the town of

Taos (Drakos et al., 2004) and springs of the Taos Plateau that are not associated with a

RGR fault, this group of springs plot to the left of the GMWL, similar to most of the

springs in this study. Additionally, groundwater samples from the Taos Plateau (Johnson

and Bauer, 2012) plot the furthest left of the GMWL, and groundwater samples near the

town of Taos (Drakos et al., 2004) plot the furthest to right of the GMWL. Well water

samples from the Valles Caldera and the southwestern outflow springs of the Valles

Caldera (Soda Dam and Jemez springs) plot along a sub-horizontal trend to the right of

the GMWL (Goff and Gardner, 1994). Women’s bathhouse spring of the Valles Caldera

(WOM) (Goff and Gardner, 1994) plots near the GMWL with the heaviest values of both

δD and δ 18O.

In figure 4, local rivers (Drakos et al., 2004) and springs throughout the Taos

Plateau not associated with a rift fault plot near the Ca-HCO3 corner of the parallelogram

of the Piper diagram. Of the western springs, Ojo Caliente waters were dominantly Na-

HCO3, conversely La Madera and Statue springs were characterized by Ca-Na-SO4-

HCO3 waters. A significant difference among the western springs was [Na]; Ojo Caliente

had [Na] of 983 ppm whereas La Madera and Statue springs had [Na] of 160 to 193 ppm.

The eastern springs plot along a mixing trend on the Piper parallelogram from Ca-HCO3

to Na-Cl waters. The Valles Caldera outflow springs also plot along the mixing trend

18

from Ca-HCO3 to Na-Cl (Goff and Gardner, 1994). The Valles Caldera springs in

Sulphur Creek (WOM and FB) are acid sulfate waters, therefore they plot near the SO4

corner of the anion triangle of the Piper diagram, conversely the wells of the Valles

Caldera plot near the Cl corner of the anion triangle and plot closer to the Valles outflow

springs in the parallelogram of the Piper diagram (Goff and Gardner, 1994).

Figures 5A-B show greater concentrations of trace elements in Ojo Caliente

springs than the remainder of the eastern and western springs of this study.

Concentrations at Ojo Caliente are [Li] = 4.29 ppm and [B] = 1.43 ppm. La Madera and

Statue springs have the next highest concentrations of [Li] = 0.29 ppm and [B] = 0.54

ppm and the eastern RGR springs have the lowest concentrations of [Li] = 0.42 ppm and

[B] = 0.57 ppm. In the subset of figures 5A-B (Li vs Cl and B vs Cl), Ojo Caliente plots

along a linear trend with Valles Caldera wells (Goff and Gardner, 1994). In figure 5C, Br

vs Cl, patterns are not evident, though the Cl/Br ratios, in table 2, can indicate increased

salinization (Hogan et al., 2007) as discussed in the multiple tracers section. Ojo Caliente

has the greatest Cl/Br ratio of 433, La Madera has the next greatest at 244, and the

eastern springs range from 14 to 150.

In table 4, the western springs have higher PCO2 than the eastern springs. The

modeled PCO2 of the western springs range from 10-0.336 to 10-0.842 atm, CO2 gas contents

ranging from 7.93 to 30.72% from sample in Giggenbach bottle and vials, and 0.41 to

0.86 cc/cc from samples in copper tube. The eastern springs have PCO2 values closer to

atmospheric values (10-3.5) (Drever, 1997) ranging from 10-1.62 to 10-3.64 and CO2 gas

content ranging from 0.02 to 4.27% from sample in Giggenbach bottle, and 0.32 and 0.33

cc/cc from samples in copper tube.

19

Figure 6 is a plot of the total C derived from external sources (Cext) versus the

corrected carbon isotope value δ13Cext (‰) for each sample. Samples plot on mixing

arrays plotted using idealized end members with a Corg endmember value of δ13Corg for

C3 plants= -22 to -34‰ and C4 plants= -9 to -16‰ (Robinson and Scrimgeour, 1995)

and arid soils from west Texas have a range of -15 to -19‰ (Deines et al., 1974). The

Cendo endmember is derived empirically from data in this study and the Valles Caldera

(Goff and Gardner, 1994; Goff and Janik, 2002), note that Valles Caldera values were

corrected for Ccarb using the same method as springs in the study area. Models are shown

in figure 6 for endmembers with Cext= 0.045 mol/L (Ojo Caliente) and Cext= 0.38 mol/L

(Valles Caldera) and δ13C that ranges from -2.5 to -6.8‰. Crossey et al. (2011) studied

the carbon isotopes in northern New Mexico and determined the endogenic range of

carbon isotopes to be -3 to -5‰, Karlstrom et al. (2013) measured the same range in

Colorado and northern New Mexico. Similar ranges of Cendo were measured in the axial

rift zones of Iceland of -3.7 to -5.3‰ (Barry et al., 2014), the Icelandic plume of -3.8‰

(Poreda et al., 1992a), the Galapogos Archipelago of -3.5‰ (Goff et al., 2000), and the

Kilauea Volcano in Hawaii of -4.1 to -3.4‰ (Gerlach and Taylor 1990). These values are

in range of upper mantle of -6.5± 2.5‰ (Sano and Marty, 1995). Proportions of Corg and

Cendo were estimated using a two component mixing model. The inset triangular plot in

Figure 6 shows the resulting proportions of the C sources based on carbon isotopes using

the calculation in section 6 “Sources of CO2 – Carbon isotope calculation”.

In figure 6, the Valles geothermal outflow plume waters (pink symbols) plot

along the mixing line with Cendo defined by Ojo Caliente and Valles Caldera springs and

wells (Fig. 6). La Madera springs also plot along this mixing line with Cext concentration

20

of 0.026 mol/L and δ13Cext of -2.4‰ (table 5). The eastern springs, Manby and Black

Rock, had δ13Cext values similar to the western side of -3.6 and -4.5‰, though they had

lower concentrations of Cext of 0.0038 and 0.0030 mol/L (Fig. 6). The two other eastern

springs, Bear Crossing and Ponce de Leon had δ13C values of -7.2 and -9.2‰, plotting

closer to an organic source.

The strontium results have large variation among spring locations. Ojo Caliente

spring waters had 87Sr/86Sr ratios of 0.747 and Sr abundances of 1.35 ppm, La Madera

and Statue springs had 87Sr/86Sr ratios of 0.718 and concentrations of 1.07 to 1.15 ppm.

Spring waters on the eastern side of the rift had lower 87Sr/86Sr values than the west with

ratios ranging from 0.708 to 0.713 and concentrations of 0.39 to 0.42 ppm, similar to

northern Rio Grande (Mills, 2003) (Fig. 7 and table 6). For comparison the Valles

Caldera wells (VC-2A and VC-2B) had similar concentrations as Ojo Caliente at 0.76 to

1.22 ppm, and 87Sr/86Sr ratios in range of La Madera and Ojo Caliente of 0.71867 to

0.73690 (Goff and Gardner, 1994). For comparison, hydrothermal vents in the ocean

have higher concentrations of 11.04 mg/L and lower 87Sr/86Sr ratios of 0.7035 (Palmer

and Edmond, 1989).

The Ar-N2-He figure showed differences among the sides of the RGR. The

western springs plotted along a mixing line between helium-rich gases and air (Fig. 8).

Conversely, the eastern springs did not plot along this mixing line rather they had excess

N2 (table 7). The second difference among the sides of the RGR was CH4 concentrations.

Ojo Caliente had 0.02 to 0.09% CH4, La Madera/Statue springs had 0.01 to 0.26% CH4,

whereas all of the eastern springs had non-detectable CH4 with the exception of Manby

with 0.01% CH4.

21

In figure 9, RC/RA values were presented along the bottom axis of the trilinear

plot of 3He, 4He and CO2. Helium isotope values in the western springs are 0.14 to 0.32

RA and eastern spring values are 0.13 to 0.20 RA (Table 8A), hence among both east and

west sides of the RGR there was 1.6 to 4.0% mantle derived helium assuming a MORB

end member of 8 ± 1 RA (Poreda et al., 1992a). The eastern and western spring data both

spread along the CO2/4He axis. Valles Caldera data (Goff and Janik, 2002) plotted closer

to the 3He apex and spreads along the CO2/3He axis. The CO2/3He values at Ojo Caliente

are 9.92x109 to 1.14x1010, La Madera/Statue springs are 8.91x1010 to 4.56x1011, and the

eastern springs range from 1.60x1010 to 4.03x1010.

11. Discussion

Goff and Gardner (1994) studied the hydrochemistry of springs to the southwest

of the Valles Caldera and showed that geothermal waters of the Caldera flowed to the

southwest along the Jemez fault and discharged in springs, in particular Soda Dam and

Jemez springs. McGibbon (2015) extended this idea by studying spring waters further

southwest along the Jemez fault in San Ysidro, NM. Evidence of distal effects of the

Valles Caldera in San Ysidro springs are shown with carbon isotopes, CO2 abundance,

non-reactive gases and presence of travertine deposits (McGibbon, 2015). Gas data from

the Valles Caldera, Soda Dam, Jemez and San Ysidro springs (Goff and Janik, 2002;

McGibbon, 2015) plotted against distance from the Valles Caldera reveal linear trends

exposing possible distal effects of the Valles Caldera at distances of 50 km, farther than

previously accepted (Figs. 10 & 11). With the same type of data plotted to the northeast

of the Valles Caldera, linear chemical trends are not as apparent, though this could be due

22

to lack of data at closer distances to the Valles Caldera. Even though these trends to the

northeast are not as well defined, distal influences of the Valles Caldera to the northeast

may become apparent by comparing the hydrochemistry of the east and west sides of the

RGR in northern New Mexico with that of the Valles geothermal system.

11.1 Discussion: Comparison of eastern and western spring groups

The eastern and western spring groups of the RGR share two commonalities, first

the isotopes of hydrogen and oxygen were mainly of meteoric origin, and second low but

detectable amounts of mantle gases are present according to helium isotope results. There

were many differences in hydrochemistry on either side of the RGR. First, the east side

had a mixing trend from Ca-HCO3 to Na-Cl waters according to the Piper diagram (Fig.

4). The western side had greater variation of water types from Na-HCO3 at Ojo Caliente

to Na-Ca-SO4-HCO3 at La Madera/Statue springs. The differences in water chemistry

among Ojo Caliente and La Madera/Statue springs could be from different water-rock

reactions, for instance La Madera could have equilibrated with gypsum increasing SO4.

The most notable difference among all the springs in terms of major ion chemistry is

greater [Na] at Ojo Caliente.

A major difference among the east and west sides was greater concentration of

geothermally-related trace elements in Ojo Caliente waters than the east side (Figs. 5A-

5B). La Madera/Statue springs, which are also on the west side like Ojo Caliente, had low

trace element concentrations similar to the east side. The differences among La

Madera/Statue springs and Ojo Caliente may again relate to different water rock

interactions, or La Madera/Statue springs could have mixed with a greater volume of a

23

shallow/meteoric water. In terms of Cl/Br ratios the eastern rift springs had Cl/Br ratios

of 14 to 150, typical of meteoric water, and the western springs had Cl/Br ratios typical of

saline subsurface waters (Phillips et al., 2003) of 244 at La Madera and 433 at Ojo

Caliente (Fig. 5C). Note the highest Cl/Br ratios are at Ojo Caliente.

The third difference was greater [Sr] in the western springs than the eastern

springs. There was large variation in the 87Sr/86Sr ratios. Ojo Caliente had the highest

87Sr/86Sr ratio, the eastern springs had the lowest ratios, and La Madera/Statue springs

had values in between (Fig. 7). The results at Ojo Caliente are interpreted as long fluid

flow through granitic bedrock. The difference among La Madera/Statue springs and Ojo

Caliente could again be different water-rock interaction or greater contribution of a

shallow mixing end member in La Madera/Statue springs.

The fourth and major difference was greater [He] measured in Ojo Caliente

waters, which again is a geothermal indicator. On the Ar-N2-He figure (Fig. 8), Ojo

Caliente and La Madera/Statue springs form a mixing line from He-rich gases to air, Ojo

Caliente plots near the He apex and La Madera plots closer to the air end member

providing additional evidence for a shallow mixing component in La Madera/Statue

springs. On the Ar-N2-He figure, the eastern springs show unclear mixing trends, the only

clear observation was that eastern springs had a greater abundance of N2 than the western

springs, therefore the eastern and western spring groups do not appear related.

Another important difference is the greater CH4 in the western springs. Methane

in these springs is not believed to be associated with hydrocarbons but reactions in

hydrothermal systems among CO2 and H2 can produce methane (Welhan, 1988).

24

The sixth and greatest difference was greater concentrations of CO2, higher

CO2/3He and Cendo (deep carbon) concentrations in western relative to eastern springs,

suggesting the western springs are more carbonic. Springs on both sides of the RGR had

similar δ13Cext values and are within range of endogenic carbon empirically derived in

this study (only considering Black Rock and Manby on the eastern side). This is

interpreted to mean that all springs have deep input based on carbon isotopes, though the

eastern springs had lower concentrations of Cendo. The presence of Cendo in all of the

springs is shown in the trilinear diagram of the percentages of each type of carbon based

on carbon isotopes (subset in Fig. 6).

In summary, of the study area Ojo Caliente waters had the highest concentrations

of Na, Cl, Li, B, Cendo, Sr, He, highest 87Sr/86Sr values, and δ13C values typical of

endogenic carbon; conversely the eastern springs had low concentrations of these tracers.

Differences in water chemistry among Ojo Caliente and La Madera/Statue springs is

interpreted as different water rock interaction and/or greater contribution of

shallow/meteoric input in La Madera/Statue springs. The main similarity among Ojo

Caliente and La Madera/Statue springs is higher concentration of Cendo, CO2, PCO2,

CO2/3He than the eastern springs.

11.2. Discussion: Comparison of Valles Caldera to Ojo Caliente

To explain greater concentrations of geothermal components in Ojo Caliente

waters, the Valles Caldera spring and well chemistries were used for comparison. The

first comparison was with trace element trends. In the plots Cl vs Li and Cl vs B, Valles

Caldera wells (VC and Baca wells) create a linear chemical trend that Ojo Caliente plots

25

along (Figs 5A-5B). The second comparison is strontium isotope data. The Valles

Caldera wells near Sulphur springs (VC-2A and VC-2B) show similar range in [Sr] and

87Sr/86Sr ratios as the western spring group.

The third comparison of Valles Caldera and Ojo Caliente water was done with

models involving CO2 and He. For the models, dissolved gas data from Valles Caldera

Baca wells was used (Truesdell and Janik, 1986). The explanation of Baca well water

chemistry was in Truesdell and Janik (1986). Water in Baca wells 4 and 13 was the

product of diluting high temperature and high salinity parent water of the Valles Caldera

geothermal system with meteoric water, the water in Baca wells 15 and 24 was the

product of conductively cooling Valles Caldera parent water.

As discussed above, Ojo Caliente had higher [He] than the other springs and may

reflect long flow though granitic bedrock. To test the idea of a connection between Valles

Caldera and Ojo Caliente via a long flow path, [He] was increased by factors of 2 from

the Baca well values on a plot of RC/RA vs CO2/He (Fig. 12). In this model the Ojo

Caliente springs plot along the trend of increasing [He]. The interpretation of this plot is

that Ojo Caliente waters can be produced from far traveled waters from the Valles

Caldera. In a similar model, 3He was exponentially decreased from Baca well values in a

plot of RC/RA vs CO2/3He (Fig. 13), and again Ojo Caliente values plotted along this

model show a less direct mantle source at Ojo Caliente.

The same trend of decreasing 3He is shown on a plot of δ13Cext vs CO2/3He (Fig.

14) as a horizontal trend along the x-axis to the right starting at MORB of 2x109 (Marty

et al., 1989) and from Footbath spring of the Valles Caldera at 1.13x109 (Goff and Janik,

2002). This horizontal trend could also be interpreted as increasing CO2, though focusing

26

only on the horizontal trend among the Baca wells, it is clear that CO2 is decreasing from

Baca wells 4 and 13 (2.81 and 4.23 cc/cc) to Baca wells 15 and 24 (0.87 and 1.37 cc/cc)

(Truesdell and Janik, 1986), which strengthens the claim that the horizontal trend among

the Baca wells is due to decreasing 3He rather than increasing CO2. The comparison of

dissolved CO2 of the Baca wells to Ojo Caliente is unclear because of the Baca wells

have such a large range of CO2 values. The Baca well data ranges from 0.87 to 4.23

cc/cc, the lower values are comparable to Ojo Caliente (0.58 to 0.65 cc/cc), however the

higher concentrations exceed Ojo Caliente values. It is notable though, that Ojo Caliente

has similar δ13Cext values as the Baca wells. This study focused on Baca well values

rather than other Valles Caldera wells and springs because the Baca well CO2

concentrations are dissolved gas measurements rather than dry gas measurements, which

is the same for Ojo Caliente. The Baca well dissolved CO2 data was from Truesdell and

Janik (1986) and was converted from mol % (CO2/H2O) to cc/cc by converting CO2 in

mols to L, then both CO2 and H2O were converted to cubic centimeters (cc/cc).

In summary, evidence of a hydrochemical connection among Ojo Caliente and the

Valles Caldera geothermal systems include 1) Ojo Caliente and Baca wells have similar

range in δ13Cext, 2) both Ojo Caliente and Valles Caldera waters follow the same trace

element trends, 3) Ojo Caliente water can be modeled from Valles Caldera water by

increasing [He] by a factor of 2 and exponentially increasing 3He, 4) lower RC/RA values

at Ojo Caliente than Valles Caldera showing less direct mantle source, 5) greater

concentrations of CO2, CH4, Cext, and higher modeled PCO2 at Ojo Caliente and La

Madera springs than the eastern spring group of the RGR. All these findings can be

explained by closer proximity to the still-active Valles geothermal system.

27

11.3. Discussion: Local CO2 story among the western spring group

Travertine deposition at La Madera is significant because it suggests a near

reservoir of deeply sourced CO2, though travertine deposition is only present at La

Madera rather than at Ojo Caliente. Similarly, higher CO2 concentrations were measured

at La Madera/Statue springs (0.41 to 0.86 cc/cc) than Ojo Caliente springs (0.58 to 0.65

cc/cc). Higher CO2 at La Madera/Statue springs is also apparent in CO2/3He ratios. La

Madera/Statue CO2/3He values are 8.91x1010 to 4.56x1011 and Ojo Caliente CO2/3He

values are 9.92x109 to 1.14x1010. Figures 9, 12 and 13 show the large range of CO2/3He

and CO2/He values while RA values remain relatively constant among the western

springs. The complexity of CO2/3He data was explained in the multiple tracer section, in

summary the variation among CO2/3He and CO2/He values from Ojo Caliente to La

Madera/Statue springs could be due to different in solubilities of He and CO2 (Marty et

al., 1989) and/or He and CO2 traveling in a gas phase rather than water (Sano et al., 1988)

(Fig. 11 & 12).

Several other parameters show greater equilibration of CO2 in La Madera/Statue

springs than Ojo Caliente. The first parameter is greater acidity at La Madera, Ojo

Caliente pH = 6.6 and La Madera = 6.0. The second parameter is higher PCO2 at La

Madera, Ojo Caliente = 10-0.26 and La Madera = 100.03. The third parameter is greater

equilibration of calcite at La Madera, calcite SI at Ojo Caliente = -1.07 and La Madera =

-0.8. These differences among La Madera and Ojo Caliente is likely structurally related.

Future work is needed to understand the structures causing greater CO2 degassing at La

Madera.

28

12. Conclusions

Due to the complex hydrogeology of geothermal systems, the focus of this work

is on using geochemistry to study the origins of spring waters in northern New Mexico.

Based on major ion chemistry, trace elements, gas abundance, carbon, strontium and

helium isotopes we conclude there are distal influences of the Valles geothermal system

in Ojo Caliente spring waters. Faults are likely the conduit for fluid and gas transport

based on previous work demonstrating fluid transport along faults (Easley and Morgan,

2013; Fischer and Chiodini, 2015; Karlstrom et al., 2013; Lee et al., 2016; Mailloux et

al., 1999), in particular fault intersections provide conduits for pristine mantle gases (de

Moor et al., 2013). The faults involved are likely the Embudo and Ojo Caliente faults. In

general, springs closer in proximity to the Embudo fault are hotter, possibly reflecting the

role of the Embudo fault transporting deep fluids. High temperature waters at Ojo

Caliente are not likely from a plume from the Valles rather deep circulation of meteoric

water. However, the Caldera may be implicated to explain the small volumes of chemical

geothermal indicators.

The distal influences of the Valles Caldera may be explained by a large advection

system, where volatiles and water originating deep in the Caldera, flow along faults and

surface at far distances. There may be more than one source of deep volatiles in the Ojo

Caliente springs. Figure 15 shows several possible gas sources and pathways, suggesting

that waters at Ojo Caliente are a mixture of deeply sourced gases. In particular, another

likely source of volatiles in the Ojo Caliente springs is partially melted mantle associated

with the Jemez lineament. The Jemez lineament passes through the entire study site and

29

may influence the hydrochemistry of all the springs. Ojo Caliente is of particular interest

because of its connection with both the Jemez lineament and the Valles Caldera.

30

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Figure Captions

Figure 1A. Mantle tomographic image at 80 km depth of New Mexico from

Schmandt and Humphreys (2010)

The study area is in north-central New Mexico at the intersection of the Rio Grande rift

(RGR) and the Jemez lineament. The RGR is outlined by a dotted line along a north-

south trend in the central part of New Mexico and is characterized by a series of half

grabens. The Jemez lineament is shown as the black basalt fields located along the

Yavapai-Mazatzal transition zone, dashed white line (Nereson et al., 2013). Orange/red =

slow velocity and blue = fast (Schmandt and Humphreys, 2010). Slow mantle velocity

domains contain partial melt, are warmer and more buoyant.

Figure 1B. Study Area showing Valles Caldera and springs

The base map is the geologic map of New Mexico from the New Mexico Bureau of

Mines and Mineral Resources with regional faults. The red lines show the dominate faults

associated with springs of this and related studies. The orange opaque area trending

north-to-south is the RGR composed of the San Luis, Espanola and Albuquerque (ABQ)

basins. The bold red lines are main faults of the study area. The bold black lines are cross

section lines. The symbol colors represent different spring groups. Yellow symbols =

western RGR spring group; black = eastern RGR spring group; blue = meteoric springs

located on either side of the RGR; red = Valles Caldera springs; pink = geothermal

outflow plume of the Valles Caldera; white = Tierra Amarilla and Penasco springs (Goff

and Janik, 2002; Vuatez et al., 1988; Truesdell and Janik, 1986). Abbreviations for the

springs are in table 1 and listed here: La Madera Mother spring (LM1), La Madera pool

(LM2), Ojo Caliente well (OC-W), Ojo Caliente Iron (OC-I), Ojo Caliente Lithium (OC-

46

L), Statue (STU), Black Rock (BR), Manby (MBY), Bear Crossing (BC), Ponce de Leon

(PL), Big spring (BS), Taos Junction (TJ), Rio Grande spring (RG), No Agua well (NA),

Tusas warm spring (TW), Picuris warm spring (PW), Footbath (FB), Women’s Bath

(WOM), Valles Caldera wells (VC-2A and VC-2B), Baca wells (B13, B15, B24, B4),

Soda Dam (SD), Jemez spring (JZ), Salt spring (Salt), “C” spring (C), Upper Owl (UO),

Zia hot well (Zia), North Highway (NH), Twin Mounds (TM), Grassy spring (GRS),

Chimayo (CHI).

Figure 2. W-E cross of southern San Luis basin of the Rio Grande Rift

W-E cross section of the RGR from Ojo Caliente to the base of the Sangre de Cristo

Mountains (Bauer and Kelson, 2004). Normal faults into basement rock are located on

either side of the RGR, motivating the study of deep volatiles ascending along the faults.

The Gorge fault and Picuris-Pecos faults are both projected into the cross section; the

former is an eastern rift-bounding fault and has greater displacement than the western

rift-bounding faults, reflecting the half graben basin geometry that is present throughout

the RGR. The RGR fill is Tertiary sediment of the Santa Fe Group overlain by basalt

flows. To the west of the RGR are the Tusas Mountains with Proterozoic granite and

metarhyolite that is faulted by the Ojo Caliente normal fault.

Figure 3. Stable isotopes of hydrogen and oxygen

The stable isotopes of hydrogen and oxygen show how spring water samples compare to

the Global Meteoric Water Line (GMWL), shown as a black line. Western and eastern

spring water samples (yellow and black symbols, respectively) plot close to the GMWL

showing the dominance of meteoric H2O. Conversely, the Valles Caldera well samples

(VC and Baca wells – red symbols) are a part of a geothermal system and underwent

47

water-rock interaction seen as a roughly horizontal trend line extending away from the

GMWL (Goff and Gardner, 1994; Truesdell and Janik, 1986).

Figure 4. Piper diagram of study area springs and Valles Caldera

The Piper diagram visually relates water samples based on major ions. The blue symbols

are more meteoric and generally plot in the left hand corner of the parallelogram, these

waters are dominantly Ca-HCO3. The yellow symbols represent spring waters from the

western RGR, which have a large range in water type. The black symbols represent

spring waters from the eastern RGR and show a mixing trend from Ca-HCO3 to Na-Cl

waters. A similar mixing trend is present in the geothermal plume waters of the Valles

Caldera, pink symbols, and may reflect similar geothermal processes.

Figure 5. Cross plots of geothermal-associated trace element concentrations

(Li,B,Br,Cl)

(A) Ojo Caliente has the highest concentrations among the springs in the study site and

lies along a trend line with the Valles Caldera. (B) B shows similar trends as Li. (C) Br vs

Cl does not show patterns, although the Cl/Br ratios distinguish spring groups; meteoric

waters have ratios of 50-150 and deep flowpath waters are greater than 200 (Phillips et

al., 2003). Eastern rift springs have Cl/Br ratios of 14 to 150 (meteoric) and western rift

springs have Cl/Br ratios of 244 to 433 (deep flow path).

Figure 6. External carbon plot of δ13Cext vs. Cext concentration

The carbon load in springs is modeled as three components: CO2 derived from dissolved

carbonates, soil degassing from organic material and CO2 derived from endogenic

degassing. The organic end member has low external carbon concentration and δ13Cext

values around -28‰; the endogenic end member has high external carbon concentration

48

and δ13Cext values empirically bracketed at -2.5 to -3.5‰. The bracketed endogenic

values were established by Valles Caldera (red symbols) and Ojo Caliente springs

(yellow symbols with δ13Cext of -3.5 to -6.8‰). Of the springs in the study area the

western springs (yellow symbols) have greater external carbon concentrations and the

eastern springs (black symbols) have smaller concentrations. Among the eastern springs,

Manby and Black Rock have δ13Cext values characteristic of endogenic origins (-3.6 and -

4.5‰), and Bear Crossing and Ponce de Leon have lighter δ13Cext values (-7.2 and -

9.2‰) trending towards the organic end member. The inset is a trilinear diagram showing

the percentages of each source CO2 in each spring. Most of the springs plot near the

endogenic apex and the meteoric springs (blue symbols) trend away from the endogenic

apex and have about equal percentages of Ccarb and Corg. Valles Caldera values are from

Goff and Janik (2002).

Figure 7. Radiogenic strontium

Strontium concentration plotted against radiogenic strontium ratios (87Sr/86Sr) highlights

that both parameters are the greatest at Ojo Caliente compared to the remainder of the

springs in the study area. Higher radiogenic strontium in Ojo Caliente spring waters is

evidence of water flowing through Precambrian granitic bedrock. Similarly, springs in

the geothermal outflow plume to the southwest of the Valles Caldera and the VC-wells

are high in both parameters (Goff and Janik, 2002). The Valles Caldera Women’s

bathhouse spring (WOM) had low [Sr] because they are fluids formed from condensed

gases. The eastern springs are low in both parameters similar to the Rio Grande (blue

squares) (Mills, 2003).

Figure 8. Dissolved gases of study area and free gases of the Valles Caldera

49

Dissolved gases of the springs in the study area and free gases of the Valles Caldera

(Goff and Janik, 2002; Truesdell and Janik, 1986) are displayed as proportions of Ar-N2-

He to identify mixing trends between helium rich (endogenic) gases and air-like gases.

The western springs best plot along this mixing line with the greatest concentration of

deeply derived gases at Ojo Caliente. All of the eastern springs have excess N2.

Figure 9. Trilinear plot of helium isotopes and CO2

The bottom axis of the trilinear plot is RC/RA; higher RC/RA means greater mantle helium

(3He) and lower RC/RA means greater crustal helium (4He) (See multiple tracers and their

uses for explanation of RC/RA). All of the springs in the study area plot above 0.1 RA,

therefore we conclude mantle degassing from springs occurs throughout the study area.

Valles Caldera and outflow springs from the Valles Caldera are from Goff and Janik

(2002) and Truesdell and Janik (1986).

Figure 10: RC/RA plotted against distance from the Valles Caldera

Springs from the Valles Caldera to the southwest are shown as negative values on the x-

axis and springs to the northeast are positive values. Red symbols are Valles Caldera

springs and wells (Goff and Janik, 2002; Goff and Gardner; 1994). Pink symbols are

Soda Dam and Jemez springs of the Valles Caldera geothermal outflow plume waters

(Goff and Janik, 2002). White symbols are from San Ysidro area (McGibbon, 2015).

Peach diamond symbols are Abiquiu spring and Chimayo spring. Yellow symbols are the

western spring group of this study and black symbols are the eastern spring group.

Figure 11: CO2/3He plotted against distance from the Valles Caldera

50

The same symbols are used here as in figure 10. This model suggests that the addition of

4He relative to 3He, at constant CO2, can account for these trends. Fractionation among

CO2 and 3He account for greater variability (lower r2) in this figure than in RC/RA vs

distance.

Figure 12: 3He/4He (expressed at RC/RA) vs CO2/He

The curved lines are a model of increasing [He] by factors of *2. This model was created

with Baca well values and then exponentially increasing [He]. Ojo Caliente springs lie

along the modeled lines revealing a possible connection with the Valles Caldera. There is

a large spread in CO2/He data in the western springs (yellow symbols), explained by

increasing CO2 from Ojo Caliente to La Madera/Statue springs with a constant RA. Soda

Dam and Jemez spring data is from dry gas data, and has similar values to La

Madera/Statue springs. Valles Caldera data shown as circles are dry gas values and

triangles are dissolved gas values. Valles Caldera and outflow springs from the Valles

Caldera are from Goff and Janik (2002) and Truesdell and Janik (1986).

Figure 13: Graph of 3He/4He (expressed at RC/RA) vs CO2/3He

Similar to figure 12, the curved lines represent a model of decreasing 3He from the Baca

wells. Again Ojo Caliente plots near the modeled lines. Same increasing CO2 trends as in

figure 12 are visible from Ojo Caliente to La Madera/Statue springs. Valles Caldera and

outflow springs from the Valles Caldera are from Goff and Janik (2002) and Truesdell

and Janik (1986).

Figure 14: δ13Cext vs CO2/3He graph

51

Valles Caldera samples plot close to MORB (CO2/3He = 2x109) and along a horizontal

trend to the right away from MORB. This horizontal trend from Baca wells 4 and 13 to

Baca wells 15 to 24 is from decreasing 3He because CO2 is also decreasing according to

dissolved gas data from Truesdell and Janik (1986), therefore the horizontal trend is

explained by decreasing 3He. Because of the large range in CO2 data among Baca wells it

is not clear if CO2 is decreasing from Baca wells to Ojo Caliente springs, though it is

notable that Ojo Caliente CO2/3He values overlap with Baca well values. The springs

with lighter δ13Cext values are Ponce de Leon (PL) and meteoric waters (blue symbols).

Figure 15: NE-SW Cross section from the Valles Caldera to the western spring

group along the hypothesized Embudo fault zone flow path and schematic drawing of

volatile degassing.

A main source of the high CO2 for the Ojo Caliente system may be magma chambers

associated with the Valles Caldera. Transport could be along the Paleozoic aquifers

(gray), brittle ductile transition (about 6-8 km) or via pathways from the mantle. This

cross section is parallel to the Jemez lineament and Embudo fault zone. The convecting

geothermal waters of the Valles Caldera are shown flowing to the southwest and

discharging along the Jemez fault (projected). The magma body locations were

interpreted from Steck et al. (1998). The cross section was adapted from Goff et al.

(2015), Koning et al. (2011), Judson (1984), and maps from the New Mexico Bureau of

Geology including the Valles Caldera cross section by Scholl and colleagues (2011), and

the Vallecitas, Chili and Ojo Caliente Quad maps.

52

Table 1: Spring abbreviations, locations and parameters

Source Sample name Abbr.Sample date

Elev (ft) Latitude Longitude

Temp ⁰C pH

Cond (μS)

TDS (ppm)

This s tudyLa Madera Mother spring LM1 01/04/15 6657 36.361000 -106.041930 25.4 6.02 1610 805

This s tudyLa Madera Mother spring LM1 06/20/15 6657 36.361000 -106.041930 25.9 5.77 1686 843

This s tudy La Madera pool LM2 01/04/15 6439 36.360990 -106.050700 24.5 6.32 1250 614

This s tudy La Madera pool LM2 06/20/15 6439 36.360990 -106.050700 26.1 6.07 1773 886

This s tudyOjo Ca l iente Wel l OC-W 01/04/15 6261 36.305492 -106.051980 53.2 6.63 3350 1700

This s tudyOjo Ca l iente Li thium spring OC-L 01/04/15 6261 36.304573 -106.052953 41.7 6.68 3150 1810

This s tudyOjo Ca l iente Iron spring OC-I 01/04/15 6261 36.304346 -106.053002 40.6 6.62 4240 2110

This s tudy Statue spring STU 01/05/15 6770 36.382080 -106.060130 25 6.34 1582 790

This s tudy Statue spring STU 06/20/15 6770 36.382080 -106.060130 28.5 5.78 1598 800

This s tudyBlack Rock spring BR 01/06/15 6540 36.530668 -105.712160 38.3 7.61 810 405

This s tudy Manby spring MBY 06/06/15 36.506748 -105.723633 38.5 7 788 394

This s tudyBear Cross ing spring BC 06/06/15 36.714430 -105.693300 16.8 7.69 232 116

This s tudyPonce de Leon spring PL 01/06/15 7266 36.321998 -105.605657 33 8.6 769 384

This s tudy Big spring BS 01/05/15 6106 36.278600 -105.793500 21.9 7.77 269 134

This s tudyTaos Junction spring TJ 01/05/15 6074 36.334180 -105.736540 18.2 7.92 463 231

This s tudyRio Grande Spring RG 01/05/15 6140 36.332630 -105.739430 15.2 7.29 391 195

This s tudy No Agua wel l NA 06/26/15 7656 36.761831 -105.958264 31 6.96 147.3 77.8

This s tudyTusas warm Spring TW 06/26/15 36.834718 -106.214072 17.3 7.31 138.1 68

This s tudyPicuris warm Spring PW 06/27/15 8104 36.249200 -105.727420 14.8 5.33 36.2 18.1

Goff and Janik (2002); Goff and Gardner (1994) Footbath FB 1986-1998 nr 35.908045 -106.615599 20 1.10 nr nr

Goff and Janik (2002); Goff and Gardner (1994) Women bath WOM 1993-1998 nr 35.906420 -106.616397 88 1.40 nr nr

Goff and Janik (2002); Goff and Gardner (1994)

Val les Ca ldera wel l VC-2A VC-2A 6/9/1905 nr 35.907595 -106.615534 210 6.20 nr nr

Goff and Janik (2002); Goff and Gardner (1994)

Val les Ca ldera wel l VC-2B VC-2B 1989-1990 nr 35.91013 -106.60949 295 4.74 nr nr

Western Rio Grande Rift springs

Eastern Rio Grande Rift springs

Meteoric Waters in study area

Valles Caldera springs and wells

53

Table 1 continued: Spring abbreviations, locations and parameters

Source Sample name Abbr.Sample date

Elev (ft) Latitude Longitude

Temp ⁰C pH

Cond (μS)

TDS (ppm)

Truesdel l and Janik (1986); Goff and Gardner (1994) Baca wel l 13 B13 1974-1982 nr 35.896512 -106.568831 289 7.30 nr nrTruesdel l and Janik (1986); Goff and Gardner (1994) Baca wel l 15 B15 1976-1982 nr 35.893188 -106.580717 280 7.12 nr nr

Truesdel l and Janik (1986)

Baca wel l 24 B24 1981-1982 nr 35.885825 -106.581993 260 nr nr nr

Truesdel l and Janik (1986)

Baca wel l 4 B4 1973-1982 nr 35.888989 -106.571063 295 nr nr nr

Goff and Janik (2002); Goff and Gardner (1994) Soda Dam SD 1984-1994 nr 35.791681 -106.686041 47 nr nr nr

Goff and Janik (2002); Goff and Gardner (1994) Jemez spring JZ 1984-1992 nr 35.77198 -106.69011 75 nr nr nr

Goff and Janik (2002) "C" Spring C 1988 nr 35.60657 -106.88540 19 nr nr nr

Goff and Janik (2002) Zia hot wel l Zia 1992 nr 35.6456 -106.8883 55 nr nr nr

McGibbon UNM Master's Thes is (2015) North Highway NH 6/30/2014 nr 35.54715 -106.82679 20.18 6.01 9430 4710

McGibbon UNM Master's Thes is (2015) Twin Mounds TM 6/30/2014 nr 35.53674 -106.84757 27.7 6.07 12560 6370

McGibbon UNM Master's Thes is (2015) Grassy Spring GRS 6/30/2014 nr 35.51618 -106.84398 24.4 6.3 15330 7600

Goff and Janik (2002) Chimayo CHI 1995 nr 35.990395 -105.943834 15 nr nr nr

Other regional springs of interest

Valles Caldera SW geothermal outflow springs

Tierra Amarilla

54

Table 2: Trace element concentrations and stable isotopes of hydrogen and oxygen

Sample name F Br Li B As Cl/Br δ18O (‰) δD (‰)

Western Rio Grande Rift springsLa Madera Mother spring 1.63 0.30 0.28 0.48 -0.10 339.0 -14.44 -99.45La Madera Mother spring 0.91 0.41 0.22 0.54 na 244.0 -14.11 -97.47La Madera pool 1.67 0.30 0.29 0.49 -0.04 366.6 -14.41 -100.11La Madera pool 0.93 0.41 0.24 0.60 0.00 269.3 -14.24 -99.16Ojo Caliente Well 15.39 0.69 4.29 1.42 0.21 351.5 -14.51 -107.47Ojo Caliente Lithium spring 13.10 0.66 4.20 1.34 0.19 351.6 -14.70 -107.34Ojo Caliente Iron spring 14.13 0.78 4.26 1.43 0.20 307.1 -14.44 -106.72Statue spring 1.54 0.29 0.51 0.52 0.04 433.6 -13.84 -99.08Statue spring 0.87 0.52 0.21 0.53 0.00 188.6 -13.95 -98.34Eastern Rio Grande Rift springsBlack Rock spring 3.00 0.59 0.42 0.30 0.04 114.9 -14.67 -103.35Manby spring 3.52 1.18 0.27 0.29 0.02 43.3 -14.37 -103.92Bear Crossing spring 0.88 0.55 0.03 0.07 0.01 14.1 -15.38 -105.73Ponce de Leon spring 12.75 0.74 0.37 0.57 0.01 149.8 -13.21 -94.35Meteoric Waters in study areaBig spring 1.06 bdl 0.13 0.07 0.03 na -15.07 -106.85Taos Junction spring 1.68 bdl 0.18 0.17 0.02 na -15.26 -108.42Rio Grande Spring 0.95 0.09 0.16 0.08 0.02 51.4 -14.73 -102.93No Agua well 0.37 0.45 0.01 0.03 0.00 5.5 -14.79 -105.25Tusas warm Spring 0.18 n.a. na 0.03 0.00 na -15.77 -109.53Picuris warm Spring 0.15 n.a. 0.03 0.03 0.03 na -13.81 -95.45

Valles Caldera springs and wellsFootbath 10.6 <0.4 0.17 0.2 nr na -20.4 -82.1Women bath 5.2 <0.4 0.17 0.2 0.04 na -8.45 -60.8Valles Caldera well VC-2A 5.68 5.9 26.5 25.6 1.92 498.8 -7.1 -74.4Valles Caldera well VC-2B 5.67 13.6 32.8 29.6 <0.1 305.1 -7.5 -85.2Baca well 13 7.2 5.3 17.0 17.0 1.6 357.9 -9.85 -87.0Baca well 15 5.5 5.9 15.0 17.0 2.3 354.7 -8.5 -84.0Baca well 24 nr nr nr nr nr na -8.6 -82.0Baca well 4 nr nr nr nr nr na -10.0 -87.5Valles Caldera SW geothermal outflow springsSoda Dam 3.33 4.6 13.8 12.1 1.5 328.9 -10.56 -84.9Jemez spring 4.99 2.4 8.9 7.34 0.7 377.1 -10.46 -81.9Tierra AmarillaNorth Highway 2.89 4.29 0.10 0.24 0.00 386.0 -10.01 -85.23Twin Mounds 3.18 4.36 8.36 10.57 0.17 445.9 -10.95 -87.82Grassy Spring 13.42 10.82 9.43 10.32 0.12 287.1 -10.00 -84.10

55

Table 3A: Major ion chemistry

Sample name Ca ppm Mg Na K HCO3 Cl SO4 balance%

Western Rio Grande Rift springsLa Madera Mother spring 138.4 52.5 174.4 18.2 673.6 101.1 268.2 -0.5La Madera Mother spring 138.4 52.5 174.4 18.2 673.6 101.1 268.2 -0.5La Madera pool 148.2 55.2 185.0 20.7 789.6 109.3 285.7 -3.4La Madera pool 148.2 55.2 185.0 20.7 789.6 109.3 285.7 -3.4Ojo Caliente Well 19.5 6.5 980.4 34.5 2027.0 242.8 150.4 2.1Ojo Caliente Lithium spring 24.1 9.2 949.0 32.2 2011.1 232.0 145.7 1.7Ojo Caliente Iron spring 21.9 7.9 983.0 33.3 2025.8 239.1 147.7 2.6Statue spring 128.6 56.3 159.9 13.3 660.2 127.8 216.3 -1.6Statue spring 132.6 50.2 160.2 17.9 702.9 97.9 251.9 -3.6Eastern Rio Grande Rift springsBlack Rock spring 21.2 5.2 148.6 11.7 196.2 68.0 141.0 1.1Manby spring 24.6 4.7 127.6 9.8 204.4 51.1 130.5 -0.6Bear Crossing spring 16.3 4.9 20.5 2.8 109.6 7.7 11.5 -1.6Ponce de Leon spring 10.7 0.7 150.2 4.1 91.5 111.3 150.1 -3.6Meteoric Waters in study areaBig spring 29.5 1.7 28.3 4.9 163.6 2.2 10.8 -0.1Taos Junction spring 14.4 1.5 100.9 4.1 281.9 2.8 20.8 1.9Rio Grande Spring 34.4 6.2 33.2 3.4 140.9 4.8 68.0 -1.4No Agua well 23.9 4.9 10.4 4.6 115.4 2.5 3.2 3.2Tusas warm Spring 30.8 4.2 4.3 2.1 137.3 0.9 1.3 -4.0Picuris warm Spring 5.3 1.4 1.3 0.8 20.7 0.6 2.5 0.8

Valles Caldera springs and wellsFootbath 56 26.5 10.8 94 bdl bdl 7900Women bath 131 50 18.9 72 bdl 1.5 6400Valles Caldera well VC-2A 5.9 0.14 1842 308 273 2943 55 -0.2Valles Caldera well VC-2B 78.5 0.76 2350 700 105 4150 7.8 2.1Baca well 13 3.4 0.04 1146 244 168 1897 42 -0.8Baca well 15 12.4 0.02 1196 261 48 2093 29 -0.9Valles Caldera SW geothermal outflow springsSoda Dam 331.0 23.60 1006.0 179.50 1527 1513.0 35.3 -1.2Jemez spring 129.0 4.66 644.0 69.00 729 905.0 41.5 -2.3Zia hot well 282.0 54.80 3320.0 63.30 1445 2890.0 3030.0 -1.1Tierra AmarillaNorth Highway 273.1 62.6 2175.1 76.2 1975.7 1656.9 1415.9 3.0Twin Mounds 396.0 66.7 3063.5 84.0 2478.5 1944.3 2906.4 1.5Grassy Spring 479.6 119.4 3863.0 154.6 1946.4 3107.4 4362.4 -1.1

56

Table 3B: Major ion in mol/L concentrations

Sample name Ca mol/LMg Na K HCO3 Cl SO4

Western Rio Grande Rift springsLa Madera Mother spring 0.0036 0.0025 0.0084 0.0004 0.0099 0.0030 0.0039La Madera Mother spring 0.0035 0.0022 0.0076 0.0005 0.0107 0.0029 0.0028La Madera pool 0.0037 0.0027 0.0083 0.0004 0.0108 0.0031 0.0029La Madera pool 0.0037 0.0023 0.0081 0.0005 0.0125 0.0031 0.0030Ojo Caliente Well 0.0005 0.0003 0.0428 0.0009 0.0327 0.0069 0.0016Ojo Caliente Lithium spring 0.0006 0.0004 0.0414 0.0008 0.0324 0.0066 0.0015Ojo Caliente Iron spring 0.0005 0.0003 0.0429 0.0009 0.0326 0.0068 0.0015Statue spring 0.0032 0.0023 0.0070 0.0003 0.0105 0.0036 0.0023Statue spring 0.0033 0.0021 0.0070 0.0005 0.0111 0.0028 0.0026Eastern Rio Grande Rift springsBlack Rock spring 0.0005 0.0002 0.0063 0.0003 0.0030 0.0016 0.0016Manby spring 0.0006 0.0002 0.0056 0.0002 0.0033 0.0014 0.0014Bear Crossing spring 0.0004 0.0002 0.0009 0.0001 0.0018 0.0002 0.0001Ponce de Leon spring 0.0003 0.0000 0.0065 0.0001 0.0014 0.0031 0.0016Meteoric Waters in study areaBig spring 0.0007 0.0001 0.0012 0.0001 0.0026 0.0001 0.0001Taos Junction spring 0.0004 0.0001 0.0044 0.0001 0.0045 0.0001 0.0002Rio Grande Spring 0.0009 0.0003 0.0014 0.0001 0.0023 0.0001 0.0007No Agua well 0.0006 0.0002 0.0005 0.0001 0.0019 0.0001 0.0000Tusas warm Spring 0.0008 0.0002 0.0002 0.0001 0.0022 0.0000 0.0000Picuris warm Spring 0.0001 0.0001 0.0001 0.0000 0.0003 0.0000 0.0000

Valles Caldera springs and wellsFootbath 0.0014 0.0011 0.0005 0.0024 bdl bdl 0.0829Valles Caldera well VC-2A 0.0001 0.0000 0.0806 0.0079 0.0052 0.0835 0.0006Valles Caldera well VC-2B 0.0020 0.0000 0.1030 0.0180 0.0002 0.1179 0.0001Baca well 13 0.0001 0.0000 0.0500 0.0063 0.0022 0.0537 0.0004Baca well 15 0.0003 0.0000 0.0522 0.0067 0.0005 0.0593 0.0003Valles Caldera SW geothermal outflow springsSoda Dam 0.0086 0.0009 0.0420 0.0041 0.0228 0.0419 0.0004Jemez spring 0.0034 0.0002 0.0278 0.0017 0.0116 0.0259 0.0004Tierra AmarillaNorth Highway 0.0069 0.0026 0.0953 0.0020 0.0308 0.0471 0.0149Twin Mounds 0.0100 0.0028 0.1347 0.0022 0.0382 0.0555 0.0306Grassy Spring 0.0121 0.0050 0.1704 0.0040 0.0297 0.0889 0.0461

57

Table 4: Saturation indexes and CO2 concentrations

Sample name SI - Calcite SI - Dolomite SI - Gypsum SI - CO2(g)Western Rio Grande Rift springsLM1 mother spring -0.89 -1.85 -1.14 0.02LM 2 Pool by HWY -0.5 -1.08 -1.1 -0.22Ojo Caliente Well -0.17 -0.31 -2.34 -0.19Ojo Caliente Lithium spring -0.17 -0.26 -2.27 -0.33Ojo Caliente Iron spring -0.28 -0.51 -2.31 -0.27Statue spring -0.84 -1.73 -1.18 0.04Eastern Rio Grande Rift springsBlack Rock -0.35 -0.9 -1.96 -2.09Manby -0.63 -1.52 -1.93 -1.62Bear Crossing -0.56 -1.4 -2.97 -2.7Ponce de Leon 0.15 -0.46 -2.22 -3.64Meteoric Waters in study areaTaos Junction -0.02 -0.75 -2.85 -2.52No Agua -0.89 -2.06 -3.37 -1.86Tusa warm -0.56 -1.73 -3.65 -2.22*Picuris warm -4.08 -8.52 -3.99 -1.05

*CO2 was analyzed in The Volcanic Geothermal Fluid Analysis Laboratory at University of New Mexico All samples, except those with an asterisk (*), were collected in a Giggenbach bottle

SI were modeled in PHREEQC

58

Table 5: Stable isotopes of carbon

Sample nameCarbon isotope

analysis measured δ 13C δ 13Cext DIC (mol/L) Ccarb Cext Ccarb(%) Corg (%) Cendo (%)Western Rio Grande Rift springs

La Madera Mother spring WB -1.02 -1.1 0.0285 0.0028 0.026 8.0 0 92.0La Madera Mother spring WB *8.23 8.8 0.0458 0.0023 0.043 6.2 0 93.8La Madera Mother CT -2.20 -2.4 0.0285 0.0023 0.026 8.0 0.36 92.4La Madera pool WB 2.32 2.8 0.0212 0.0034 0.018 16.1 0 83.9La Madera pool WB 3.47 3.8 0.0332 0.0030 0.030 9.0 0 91.0Ojo Caliente Well WB -3.47 -3.5 0.0454 0.0003 0.046 0.6 3.9 95.5Ojo Caliente Well CT -6.80 -6.8 0.0454 0.0003 0.045 0.6 16.8 82.6Ojo Caliente Lithium spring WB -3.45 -3.5 0.0440 0.0004 0.045 0.9 3.5 95.6Ojo Caliente Iron spring WB -3.54 -3.6 0.0460 0.0003 0.047 0.7 4.3 95.0Statue spring WB 0.36 0.40 0.0201 0.0033 0.017 16.3 0 83.7Statue spring WB *6.11 6.5 0.0460 0.0028 0.043 6.0 0 94.0Eastern Rio Grande Rift springsBlack Rock spring WB -4.23 -4.5 0.0032 0.00018 0.0030 5.7 7.4 87.0Manby spring WB -3.47 -3.6 0.0039 0.00020 0.0038 4.9 4.1 91.0Bear Crossing spring WB -5.32 -7.2 0.0019 0.00049 0.0014 26.0 13.6 60.3Ponce de Leon spring WB -9.05 -9.2 0.0015 0.00003 0.0014 2.0 25.7 72.2Meteoric Waters in study areaBig spring WB -7.90 -10.5 0.0028 0.00069 0.0021 25.0 23.5 51.5Taos Junction spring WB -6.00 -6.3 0.0047 0.00020 0.0045 4.3 14.3 81.4Rio Grande Spring WB -9.33 -11.0 0.0026 0.00040 0.0022 15.6 28.1 56.3No Agua well WB -7.25 -10.9 0.0023 0.00076 0.0015 33.3 22.0 44.7Tusas warm Spring WB -13.11 -20.9 0.0025 0.00093 0.0016 37.1 45.4 17.5Picuris warm Spring WB -9.04 -9.4 0.0045 0.00017 0.0043 3.7 26.0 70.2Valles Caldera springs and wellsFootbath Dry gas -2.47 -2.5 0.314 0.0011 0.31 0.4 0 99.6

Valles Caldera well VC-2A Dry gas -4.99 -5.0 0.054 0.0000058 0.054 0.0 9.8 90.2

Valles Caldera well VC-2B Dry gas -3.3 -3.3 0.387 0.0019 0.385 0.5 3.2 96.3Baca well 13 Dry gas -4.51 -4.5 0.0053 0.0000017 0.0053 0.0 7.9 92.1Baca well 15 Dry gas -4.77 -4.8 0.0015 0.0000083 0.0015 0.5 9.0 90.5Baca well 24 Dry gas -4.80 -4.8 0.012 0 0.012 0 9.0 91.0Baca well 4 Dry gas -4.73 -4.7 0.014 0 0.014 0 8.7 91.3Valles Caldera SW geothermal outflow springsSoda Dam Dry gas -4.90 -5.6 0.050 0.0062 0.044 12.3 10.7 77.1Jemez spring Dry gas -5.15 -6.6 0.015 0.0032 0.011 21.9 12.6 65.5Other regional springs of interestChimayo Dry gas -5.93 -6.7 0.161 0.0151 0.1461 9.4 14.2 76.4

WB: carbon isotopes analyzed from water collected in a water bottleCT: carbon isotopes analyzed from gases exolved from water in a copper tube* outlying carbon isotope value - sample is from a carbonic spring that degassed in the laboratory

59

Table 6: Radiogenic strontium

Sample Name Source Sample Date 87Sr/86Sr Sr (ppm) Rb (ppm)Western Rio Grande Rift springsLa Madera Mother Spring This s tudy 1/4/2015 0.71830062 1.15 naOjo Ca l iente Wel l This s tudy 9/10/2015 0.747376 1.30 naOjo Ca l iente Iron Spring This s tudy 9/10/2015 0.746596 1.35 naStatue Spring This s tudy 9/10/2015 0.718129 1.07 naEastern Rio Grande Rift springsBlack Rock Spring This s tudy 1/6/2015 0.7078852 0.415 naManby Spring This s tudy 9/10/2015 0.707994 0.39 naPonce de Leon Spring This s tudy 1/6/2015 0.71328700 0.231 naMeteoric Waters in study areaTaos Junction Spring This s tudy 1/5/2015 0.70776127 0.275 naRio Grande river samplesTaos Junction Campground Mi l l s , 2003 January 2001 0.708936 0.36 naCochiti Dam Mil l s , 2003 August 2001 0.709607 0.55 naCochiti Dam Mil l s , 2003 January 2001 0.709745 0.64 naAlbuquerque Mi l l s , 2003 August 2001 0.709672 0.77 naAlbuquerque Mi l l s , 2003 January 2001 0.709931 0.84 naValles Caldera springs and wellsJemez Women bathroom Vuatez et a l ., 1988 June 1985 0.710614 0.14 0.1VC-2A Goff and Gardner, 1994 8/27/1987 0.71867 0.76 4.3VC-2B Goff and Gardner, 1994 1/17/1990 0.73690 1.22 11.5Baca 13 wel l in Redondo Graben Vuatez et a l ., 1988 1982-1988 0.708423 0.14 2.7Baca 15 Vuatez et a l ., 1988 Sept. 1982 0.709412 0.13 3.1 springsSoda Dam Vuatez et a l ., 1988 June 1985 0.721932 1.5 1.8Jemez spring Vuatez et a l ., 1988 June 1985 0.721742 0.61 0.7Zia hot wel l in SE SJ Bas in Vuatez et a l ., 1988 June 1985 0.715564 7.74 0.2Valles Caldera rocksVC-1 core hole Vuatez et a l ., 1988 Sept. 1985 0.715220 1.16 0.4VC-1 core hole Vuatez et a l ., 1988 May 1986 0.715398 0.76 0.35VC-1 Goff and Gardner, 1994 9/5/1985 0.71522 1.33 0.4VC-1 Vuatez et a l ., 1988 Summer 1984 0.704854 <<300 137VC-1 Vuatez et a l ., 1988 Summer 1984 0.704766 <<300 137VC-1 Vuatez et a l ., 1988 Summer 1984 0.704593 aprox 750 aprox. 60VC-1 Vuatez et a l ., 1988 Summer 1984 0.709709 aprox. 30 aprox. 165VC-1 Vuatez et a l ., 1988 Summer 1984 0.721411 na naVC-1 Vuatez et a l ., 1988 Summer 1984 0.716129 na naVC-1 Vuatez et a l ., 1988 Summer 1984 0.716355 na naVC-1 Vuatez et a l ., 1988 Summer 1984 0.756860 na naVC-1 Vuatez et a l ., 1988 Summer 1984 0.726106 na naWells in TaosBOR 2A Drakos et a l ., 2004 5/8/2002 0.7123 na naYaravi tz Drakos et a l ., 2004 5/7/2002 0.7100 na naOW6 Drakos et a l ., 2004 5/9/2002 0.7113 na naLandfi l l MW-1 Drakos et a l ., 2004 5/9/2002 0.7094 na naBOR2B Drakos et a l ., 2004 5/8/2002 0.7156 na naRP2500 Drakos et a l ., 2004 5/1/2002 0.7086 na naBOR1-Deep Drakos et a l ., 2004 5/9/2002 0.7106 na naBOR 7 Drakos et a l ., 2004 6/13/2002 0.7074 na naBIA 9 Drakos et a l ., 2004 6/13/2002 0.7095 na naBOR 5 Drakos et a l ., 2004 8/1/2002 0.7093 na na

60

Table 7: Dissolved gases of springs in the study and free gas of the Valles Caldera

Sample name Source Ar He O2 CO2 H2 H2S N2 CH4 sumWestern Rio Grande Rift springsLa Madera Mother spring This Study 1.32 0.07 0.10 7.93 1.03 na 88.34 0.26 100.0La Madera pool This Study 0.57 0.00 14.67 2.16 0.00 na 82.60 0.00 100.01 Ojo Caliente well This Study 0.85 1.35 9.82 2.65 0.00 na 85.25 0.09 100.01 Ojo Caliente Iron spring This Study 0.74 0.66 14.75 0.03 0.00 na 83.80 0.02 100.01 Ojo Caliente Lithium spring This Study 0.54 1.72 6.51 30.72 0.00 na 60.46 0.05 100.0Statue spring This Study 0.83 0.06 17.37 25.54 0.00 na 56.17 0.01 100.0Eastern Rio Grande Rift springsBlack Rock This Study 0.60 0.02 13.54 0.94 0.00 na 84.91 0.00 100.0Manby This Study 1.11 0.33 14.74 4.27 0.00 na 79.54 0.01 100.0Bear Crossing This Study 0.80 0.03 17.53 2.00 0.00 na 79.63 0.00 100.0Ponce de Leon This Study 0.84 0.08 16.79 0.02 0.00 na 82.26 0.00 100.0Meteoric Waters in study areaBig Spring This Study 0.71 0.01 15.70 1.14 0.00 na 82.44 0.00 100.0Taos Junction This Study 0.79 0.01 17.68 0.08 0.00 na 81.44 0.00 100.0Rio Grande Spring This Study 0.55 0.01 15.01 1.51 0.00 na 82.92 0.00 100.0Tusa warm This Study 2.05 0.04 24.36 3.58 0.00 na 69.98 0.00 100.0No Agua This Study 1.14 0.03 15.01 1.47 0.00 na 82.34 0.00 100.0Picuris warm spring This Study 1.24 0.01 14.35 0.37 0.00 na 84.03 0.00 100.0*Picuris warm spring This Study 0.73 0.09 14.91 0.91 0.00 na 83.35 0.00 100.0Valles Caldera springs and wells* Footbath Goff et al., 2002 0.011 0.012 0.03 97.9 0.48 0.87 0.62 0.064 100.0* Women bathroom Goff et al., 2002 0.01 0.004 0.0041 98.5 0.1 0.71 0.69 0.016 100.0*VC-2a well Goff et al., 2002 0.016 0.002 0.0005 97.1 0.25 0.72 0.9 0.017 99.0* VC-2b well in situ Goff et al., 2002 0.0066 0.0051 0.11 96.9 1.85 0.81 0.29 0.24 100.2* Baca Well 13 Truesdell and Janik, 1986 0.0042 0.0042 nr 99.3 0.0403 0.482 0.142 0.0207 100.0* Baca Well 13 Truesdell and Janik, 1986 0.0058 0.0054 nr 99.2 0.0494 0.534 0.181 0.0244 100.0* Baca Well 15 Truesdell and Janik, 1986 0.027 0.0022 nr 96.7 0.14 1.77 1.13 0.0253 99.8* Baca Well 19 Truesdell and Janik, 1986 0.015 0.0061 nr 98.4 0.106 0.806 0.572 0.0633 100.0* Baca Well 24 Truesdell and Janik, 1986 0.017 0.0016 nr 98.5 0.0542 0.672 0.721 0.018 100.0* Baca Well 24 Truesdell and Janik, 1986 0.013 0.0018 nr 98.4 0.0323 0.778 0.679 0.0085 99.9* Baca Well 4 Truesdell and Janik, 1986 0.0083 0.0067 nr 98.5 0.0645 0.995 0.353 0.0393 100.0* Tony's spring Goff et al., 2002 0.0081 0.005 0.007 98.8 0.29 0.87 0.62 0.064 100.7* Mens Goff et al., 2002 0.016 0.0066 0.033 98.3 0.021 0.17 0.89 0.021 99.5* Main fumerole Goff et al., 2002 0.0055 0.0048 0.0016 99.0 0.044 0.77 0.25 0.033 100.1Valles Caldera SW geothermal outflow springs* Soda Dam Goff et al., 2002 0.02 0.002 0.32 98.4 0.005 0.02 1.10 0.004 99.9* Jemez spring Goff et al., 2002 0.012 0.0011 0.14 99.1 0.0001 0.063 0.71 0.005 100.0* "C" Spring Goff et al., 2002 0.05 0.040 0.14 97.7 <0.005 <0.02 1.97 0.004 99.9Other regional springs of interest* Chimayo Goff et al., 2002 0.005 0.0048 0.0020 99.8 0 0 0.166 0.0010 100.0

Samples reported in %Samples from the study site were analyzed for dissolved gases (unless labeled with an asterisk)1 sample collected in a vial - water in vial was displaced by bubbles from springSamples from this study were analyzed in The Volcanic Geothermal Fluid Analysis Laboratory at University of New Mexico

61

Table 8A: Dissolved helium and CO2 in water

Sample name Reference 3He4He CO2 CO2/3He Ne R/RA X Rc/RA

pcc/cc µcc/cc ccSTP/cc cc/cc µcc/ccWestern Rio Grande Rift springsLa Madera Mother spring This study 3.73 7.99 0.85 2.29E+11 0.73 0.34 27.4 0.318 4.0La Madera Mother spring Newell et al., 2005 9.08 1.97 0.41 4.56E+11 0.84 nr 148.2 0.330 4.1La Madera pool This study 8.85 16.30 0.79 8.91E+10 0.47 0.390 86.9 0.387 4.8Ojo Caliente Well This study 57.97 287.99 0.58 9.92E+09 8.13 0.14 672.6 0.14 1.7Ojo Caliente Well Crossey unpublished 30.19 120.48 nr nr 0.127 0.2 2371.6 0.18 2.2Ojo Caliente iron spring This study 56.57 256.98 0.65 1.14E+10 0.96 0.16 88.6 0.16 2.0Statue spring This study 6.71 17.98 0.86 1.27E+11 0.95 0.27 47.6 0.26 3.2Eastern Rio Grande Rift springsBlack Rock This study 7.90 19.97 0.32 4.03E+10 7.37 0.28 6.8 0.20 2.5Manby Newell et al., 2005 nr nr nr nr nr nr nr 0.316 4.0Ponce de Leon This study 20.59 113.57 0.33 1.60E+10 0.97 0.13 292.3 0.13 1.6Meteoric Waters in study areaBig spring This study 6.79 5.63 0.27 3.98E+10 21.32 0.87 0.7 n/a n/aNo Agua well This study 20.82 102.7 0.46 2.21E+10 12.2442 0.146 21.0 0.124 1.5Tusa Warm spring This study 8.29 84.69 0.99 1.76E+10 18.7097 0.954 0.8 n/a n/aValles Caldera springs and wells1Baca well 13 Truesdell and Janik, 1986 110.4 16.6 0.34 3.08E+09 nr 4.75 nr nr 59.41Baca well 15 Truesdell and Janik, 1986 9.3 1.6 0.07 7.55E+09 nr 4.14 nr nr 51.81Baca well 24 Truesdell and Janik, 1986 10.5 1.9 0.1 9.57E+09 nr 3.93 nr nr 49.11Baca well 4 Truesdell and Janik, 1986 83.2 15.4 0.23 2.76E+09 nr 3.86 nr nr 48.3Baca well 13 Truesdell and Janik, 1986 1175.1 176.7 4.23 3.60E+09 nr 4.75 nr nr 59.4Baca well 15 Truesdell and Janik, 1986 115.4 19.9 0.87 7.55E+09 nr 4.14 nr nr 51.8Baca well 24 Truesdell and Janik, 1986 124.8 22.4 1.37 1.10E+10 nr 3.98 nr nr 49.8Baca well 4 Truesdell and Janik, 1986 1035.6 191.6 2.81 2.72E+09 nr 3.86 nr nr 48.3

Samples from the study site were analyzed from gases exolved from water in a copper tubeValles Caldera, outflow springs from the Valles Calder and Chimayo were analyzed for free gasesHe/Ne of air used to correct measured R/Ra is 0.4X = (He/Ne)m / (He/Ne)air

Rc/Ra = (R/Ra * X - 1) / (X - 1) Samples from the study area were analyzed in the Noble gas laboratory at at Ohio State University 1 CO 2 and 4 He reported as mol% in total discharge of water

% mantle He

62

Table 8B: Dry gas - helium and CO2 data

Sample name Reference He CO2 CO2/3He R/RA

Valles Caldera springs and wellsFootbath Spring Goff and Janik, 2002 0.012 97.9 1.13E+09 5.16Womens bath Goff and Janik, 2002 0.0040 98.5 2.86E+09 6.16VC-2a well Goff and Janik, 2002 0.0020 97.1 6.94E+09 5.0VC-2b well Goff and Janik, 2002 0.0051 96.9 2.37E+09 5.72Baca well 13 Truesdell and Janik, 1986 0.0042 99.2 3.55E+09 4.75Baca well 15 Truesdell and Janik, 1986 0.0022 96.7 7.58E+09 4.14Baca well 24 Truesdell and Janik, 1986 0.0016 98.4 1.30E+10 3.93Baca well 4 Truesdell and Janik, 1986 0.0067 98.5 2.72E+09 3.86Valles Caldera SW geothermal outflow springsSoda Dam Goff and Janik, 2002 0.0020 98.4 4.18E+10 0.84Jemez hot spring Goff and Janik, 2002 0.0011 99.1 5.07E+10 1.270C spring Goff and Janik, 2002 0.0400 97.7 5.45E+09 0.320Salt Spring Newell et al., 2005 0.0046 98.4 1.33E+11 nrTierra AmarillaTwin Mounds (in paper labeled Grassy spring) Newell et al., 2005 0.0084 98.6 4.20E+10 nrOther regional springs of interestChimayo Well Goff and Janik, 2002 0.0048 99.6 2.28E+10 0.65

Analysis in mol% dry gas

63

Figures

Figure 1A: Mantle tomographic image at 80 km depth of New Mexico from Schmandt and Humphreys (2010)

The study area is in north-central New Mexico at the intersection of the Rio Grande rift

(RGR) and the Jemez lineament. The RGR is outlined by a dotted line along a north-

south trend in the central part of New Mexico and is characterized by a series of half

grabens. The Jemez lineament is shown as the black basalt fields located along the

Yavapai-Mazatzal transition zone, dashed white line (Nereson et al., 2013). Orange/red =

slow velocity and blue = fast (Schmandt and Humphreys, 2010). Slow mantle velocity

domains contain partial melt, are warmer and more buoyant.

Study area

64

Figure 1B: Study Area showing Valles Caldera and springs

The base map is the geologic map of New Mexico from the New Mexico Bureau of Mines and Mineral Resources with regional faults. The red lines show the dominate faults associated with springs of this and related studies. The orange opaque area trending north-to-south is the RGR composed of the San Luis, Espanola and Albuquerque (ABQ) basins. The bold red lines are main faults of the study area. The bold black lines are cross section lines. The symbol colors represent different spring groups. Yellow symbols = western RGR spring group; black = eastern RGR spring group; blue = meteoric springs located on either side of the RGR; red = Valles Caldera springs; pink = geothermal outflow plume of the Valles Caldera; white = Tierra Amarilla and Penasco springs (Goff and Janik, 2002; Vuatez et al., 1988; Truesdell and Janik, 1986). Abbreviations for the springs are in table 1 and listed here: La Madera Mother spring (LM1), La Madera pool (LM2), Ojo Caliente well (OC-W), Ojo Caliente Iron (OC-I), Ojo Caliente Lithium (OC-L), Statue (STU), Black Rock (BR), Manby (MBY), Bear Crossing (BC), Ponce de Leon (PL), Big spring (BS), Taos Junction (TJ), Rio Grande spring (RG), No Agua well (NA), Tusas warm spring (TW), Picuris warm spring (PW), Footbath (FB), Women’s Bath (WOM), Valles Caldera wells (VC-2A and VC-2B), Baca wells (B13, B15, B24, B4), Soda Dam (SD), Jemez spring (JZ), Salt spring (Salt), “C” spring (C), Upper Owl (UO), Zia hot well (Zia), North Highway (NH), Twin Mounds (TM), Grassy spring (GRS), Chimayo (CHI).

65

Figure 2: W-E cross of southern San Luis basin of the Rio Grande Rift

W-E cross section of the RGR from Ojo Caliente to the base of the Sangre de Cristo

Mountains (Bauer and Kelson, 2004). Normal faults into basement rock are located on

either side of the RGR, motivating the study of deep volatiles ascending along the faults.

The Gorge fault and Picuris-Pecos faults are both projected into the cross section; the

former is an eastern rift-bounding fault and has greater displacement than the western

rift-bounding faults, reflecting the half graben basin geometry that is present throughout

the RGR. The RGR fill is Tertiary sediment of the Santa Fe Group overlain by basalt

flows. To the west of the RGR are the Tusas Mountains with Proterozoic granite and

metarhyolite that is faulted by the Ojo Caliente normal fault.

66

Figure 3: Stable isotopes of hydrogen and oxygen

The stable isotopes of hydrogen and oxygen show how spring water samples compare to

the Global Meteoric Water Line (GMWL), shown as a black line. Western and eastern

spring water samples (yellow and black symbols, respectively) plot close to the GMWL

showing the dominance of meteoric H2O. Conversely, the Valles Caldera well samples

(VC and Baca wells – red symbols) are a part of a geothermal system and underwent

water-rock interaction seen as a roughly horizontal trend line extending away from the

GMWL (Goff and Gardner, 1994; Truesdell and Janik, 1986).

67

Figure 4: Piper diagram of study area springs and Valles Caldera

The Piper diagram visually relates water samples based on major ions. The blue symbols

are more meteoric and generally plot in the left hand corner of the parallelogram, these

waters are dominantly Ca-HCO3. The yellow symbols represent spring waters from the

western RGR, which have a large range in water type. The black symbols represent

spring waters from the eastern RGR and show a mixing trend from Ca-HCO3 to Na-Cl

waters. A similar mixing trend is present in the geothermal plume waters of the Valles

Caldera, pink symbols, and may reflect similar geothermal processes.

68

Figure 5: Cross plots of geothermal-associated trace element concentrations (Li,B,Br,Cl)

Ojo Caliente has the highest

concentrations among the

springs in the study site and

lies along a trend line with

the Valles Caldera. (B) B

shows similar trends as Li.

(C) Br vs Cl does not show

patterns, although the Cl/Br

ratios distinguish spring

groups; meteoric waters

have ratios of 50-150 and

deep flowpath waters are

greater than 200 (Phillips et

al., 2003). Eastern rift

springs have Cl/Br ratios of

14 to 150 (meteoric) and

western rift springs have

Cl/Br ratios of 244 to 433

(deep flow path).

A

B

C

69

Figure 6: External carbon plot of δ13Cext vs. Cext concentration

The carbon load in springs is modeled as three components: CO2 derived from dissolved carbonates, soil degassing from organic material and CO2 derived from endogenic degassing. The organic end member has low external carbon concentration and δ13Cext values around -28‰; the endogenic end member has high external carbon concentration and δ13Cext values empirically bracketed at -2.5 to -3.5‰. The bracketed endogenic values were established by Valles Caldera (red symbols) and Ojo Caliente springs (yellow symbols with δ13Cext of -3.5 to -6.8‰). Of the springs in the study area the western springs (yellow symbols) have greater external carbon concentrations and the eastern springs (black symbols) have smaller concentrations. Among the eastern springs, Manby and Black Rock have δ13Cext values characteristic of endogenic origins (-3.6 and -4.5‰), and Bear Crossing and Ponce de Leon have lighter δ13Cext values (-7.2 and -9.2‰) trending towards the organic end member. The inset is a trilinear diagram showing the percentages of each source CO2 in each spring. Most of the springs plot near the endogenic apex and the meteoric springs (blue symbols) trend away from the endogenic apex and have about equal percentages of Ccarb and Corg. Valles Caldera values are from Goff and Janik (2002).

70

Figure 7: Radiogenic strontium

Strontium concentration plotted against radiogenic strontium ratios (87Sr/86Sr) highlights

that both parameters are the greatest at Ojo Caliente compared to the remainder of the

springs in the study area. Higher radiogenic strontium in Ojo Caliente spring waters is

evidence of water flowing through Precambrian granitic bedrock. Similarly, springs in

the geothermal outflow plume to the southwest of the Valles Caldera and the VC-wells

are high in both parameters (Goff and Janik, 2002). The Valles Caldera Women’s

bathhouse spring (WOM) had low [Sr] because they are fluids formed from condensed

gases. The eastern springs are low in both parameters similar to the Rio Grande (blue

squares) (Mills, 2003).

71

Figure 8: Dissolved gases of study area and free gases of the Valles Caldera

Dissolved gases of the springs in the study area and free gases of the Valles Caldera

(Goff and Janik, 2002; Truesdell and Janik, 1986) are displayed as proportions of Ar-N2-

He to identify mixing trends between helium rich (endogenic) gases and air-like gases.

The western springs best plot along this mixing line with the greatest concentration of

deeply derived gases at Ojo Caliente. All of the eastern springs have excess N2.

72

Figure 9: Trilinear plot of helium isotopes and CO2

The bottom axis of the trilinear plot is RC/RA; higher RC/RA means greater mantle helium

(3He) and lower RC/RA means greater crustal helium (4He) (See multiple tracers and their

uses for explanation of RC/RA). All of the springs in the study area plot above 0.1 RA,

therefore we conclude mantle degassing from springs occurs throughout the study area.

Valles Caldera and outflow springs from the Valles Caldera are from Goff and Janik

(2002) and Truesdell and Janik (1986).

73

Figure 10: RC/RA plotted against distance from the Valles Caldera

Springs from the Valles Caldera to the southwest are shown as negative values on the x-

axis and springs to the northeast are positive values. Red symbols are Valles Caldera

springs and wells (Goff and Janik, 2002; Goff and Gardner; 1994). Pink symbols are

Soda Dam and Jemez springs of the Valles Caldera geothermal outflow plume waters

(Goff and Janik, 2002). White symbols are from San Ysidro area (McGibbon, 2015).

Peach diamond symbols are Abiquiu spring and Chimayo spring. Yellow symbols are the

western spring group of this study and black symbols are the eastern spring group.

74

Figure 11: CO2/3He plotted against distance from the Valles Caldera

The same symbols are used here as in figure 10. This model suggests that the addition of 4He relative to 3He, at constant CO2, can account for these trends. Fractionation among

CO2 and 3He account for greater variability (lower r2) in this figure than in RC/RA vs

distance.

75

Figure 12: 3He/4He (expressed at RC/RA) vs CO2/He

The curved lines are a model of increasing [He] by factors of *2. This model was created

with Baca well values and then exponentially increasing [He]. Ojo Caliente springs lie

along the modeled lines revealing a possible connection with the Valles Caldera. There is

a large spread in CO2/He data in the western springs (yellow symbols), explained by

increasing CO2 from Ojo Caliente to La Madera/Statue springs with a constant RA. Soda

Dam and Jemez spring data is from dry gas data, and has similar values to La

Madera/Statue springs. Valles Caldera data shown as circles are dry gas values and

triangles are dissolved gas values. Valles Caldera and outflow springs from the Valles

Caldera are from Goff and Janik (2002) and Truesdell and Janik (1986).

76

Figure 13: Graph of 3He/4He (expressed at RC/RA) vs CO2/3He

Similar to figure 12, the curved lines represent a model of decreasing 3He from the Baca

wells. Again Ojo Caliente plots near the modeled lines. Same increasing CO2 trends as in

figure 12 are visible from Ojo Caliente to La Madera/Statue springs. Valles Caldera and

outflow springs from the Valles Caldera are from Goff and Janik (2002) and Truesdell

and Janik (1986).

77

Figure 14: δ13Cext vs CO2/3He graph

Valles Caldera samples plot close to MORB (CO2/3He = 2x109) and along a horizontal

trend to the right away from MORB. This horizontal trend from Baca wells 4 and 13 to

Baca wells 15 to 24 is from decreasing 3He because CO2 is also decreasing according to

dissolved gas data from Truesdell and Janik (1986), therefore the horizontal trend is

explained by decreasing 3He. Because of the large range in CO2 data among Baca wells it

is not clear if CO2 is decreasing from Baca wells to Ojo Caliente springs, though it is

notable that Ojo Caliente CO2/3He values overlap with Baca well values. The springs

with lighter δ13Cext values are Ponce de Leon (PL) and meteoric waters (blue symbols).

78

Figure 15: NE-SW Cross section from the Valles Caldera to the western spring group along the hypothesized Embudo fault zone flow path and schematic drawing of volatile degassing.

A main source of the high CO2 for the Ojo Caliente system may be magma chambers

associated with the Valles Caldera. Transport could be along the Paleozoic aquifers

(gray), brittle ductile transition (about 6-8 km) or via pathways from the mantle. This

cross section is parallel to the Jemez lineament and Embudo fault zone. The convecting

geothermal waters of the Valles Caldera are shown flowing to the southwest and

discharging along the Jemez fault (projected). The magma body locations were

interpreted from Steck et al. (1998). The cross section was adapted from Goff et al.

(2015), Koning et al. (2011), Judson (1984), and maps from the New Mexico Bureau of

Geology including the Valles Caldera cross section by Scholl and colleagues (2011), and

the Vallecitas, Chili and Ojo Caliente Quad maps.