Chemical analyses including gold for 373 rock and stream 030 br 031 br 038 br 039 br 040 br 041 br...

Click here to load reader

download Chemical analyses including gold for 373 rock and stream 030 br 031 br 038 br 039 br 040 br 041 br 042 br 045 br 046 br 050 br 051 br 052 br 053 br 054 br 055 br 056 br 057 br 058

of 42

  • date post

    17-Apr-2018
  • Category

    Documents

  • view

    229
  • download

    6

Embed Size (px)

Transcript of Chemical analyses including gold for 373 rock and stream 030 br 031 br 038 br 039 br 040 br 041 br...

  • UNITED STATES DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY

    Chemical analyses including gold for 373 rockand stream-sediment samples from the Richfield

    1 x 2 quadrangle, Utah

    by

    J.B. McHugh*, R.T. Hopkins*, W.R. Miller*, and D.L. Fey*

    Open-File Report 91-318

    This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards. Any use of trade, product or firm names is for descriptive purposes only and does not imply endorsement by the USGS.

    *U.S. Geological Survey, DFC, Box 25046, MS 973, Denver, CO 80225

    1991

  • CONTENTS

    Page

    Introduction ..................................................................................................................... 3

    Sample Collection and Preparation................................................................................... 3

    Analytical Procedures....................................................................................................... 3

    References Cited............................................................................................................... 5

    ILLUSTRATION

    Figure 1. Location of towns, roads, and major geographic features in theRichfield quadrangle.................................................................................................. 4

    TABLES

    Table la. Detection limits and minimum, maximum values for 181 rock analyses........... 6

    Table Ib. Detection limits and minimum, maximum values for 192 stream-sedimentanalyses..................................................................................................................... 7

    Table 2. Chemical analyses for 181 rock samples, Richfield quadrangle, Utah................. 8

    Table 3. Chemical analyses for 192 stream-sediment samples, Richfield quadrangle,Utah ..................................................................................................................... 23

  • INTRODUCTION

    The Richfield 1 x 2 quadrangle (fig. 1) in west-central Utah covers the eastern part of the Pioche-Marysvale igneous and mineral belt that extends from the vicinity of Pioche in southeastern Nevada, east-northeastward for 250 km into central Utah. The western two-thirds of the Richfield quadrangle is in the Basin and Range Province; the eastern third is in the High Plateaus of Utah subprovince of the Colorado Plateau.

    Bedrock in the northern part of the Richfield quadrangle consists predominantly of Paleozoic sedimentary strata that were thrust eastward during the Sevier orogeny in Cretaceous time onto an autochthon of Mesozoic sedimentary rocks in the eastern part of the quadrangle. The southern part of the quadrangle is largely underlain by Oligocene and younger volcanic rocks and related intrusions. Extensional tectonism in late Cenozoic time broke the bedrock terrane into a series of north-trending fault blocks; the uplifted mountain areas were deeply eroded and the resulting debris were deposited in the adjacent basins. Most of the mineral deposits in the Richfield 1 x 2 quadrangle were formed during igneous activity in middle and late Cenozoic time (Steven and Morris, 1984).

    A regional geochemical survey was conducted during the summers of 1978 and 1979. Sampling was designed to define broad geochemical patterns and trends which can be used, along with geologic and geophysical data, to assess the mineral resource potential of the quadrangle. This report is a follow-up based on work done earlier in 1978 and 1979.

    In the summer of 1988, 373 rock and stream-sediment samples were collected from geochemically anomalous areas based on the earlier regional survey and analyzed for 34 elements by emission spectrography and for As, Bi, Cd, Sb, Zn by inductively coupled plasma atomic emission spectrophotometry (ICP-AES), and Au by atomic-absorption spectrophotometry.

    SAMPLE COLLECTION AND PREPARATION

    Samples were collected in June and September of 1988 at 373 sites, of these, 181 were rock samples, and 192 stream-sediment samples. Rock samples were prepared by crushing and then pulverized to minus 0.15 mm with ceramic plates. Stream-sediment samples were dried and sieved to minus-80 mesh (0.177 mm) and pulverized to approximately minus-140 mesh (0.105) in a vertical grinder having ceramic plates.

    ANALYTICAL PROCEDURES

    The elements analyzed and their detection limits and minimum, maximum values are listed in tables la and Ib. Each sample was analyzed for 34 element using a semiquantitative, direct- current arc emission spectrographic method (Grimes and Marranzino, 1968.) Spectrographic results were obtained by visual comparison of spectra derived from the sample against spectra obtained from standards made from pure oxides and carbonates. Standard concentrations are geometrically spaced over any given order of magnitude of concentration as follows: 100, 50, 20,10, and so forth. Samples whose concentrations are estimated to fall

  • UJ

    a: a

    oorUJ

    E

    a.< a:C5 O

    ccO

    O-1- O

    O Ci

    XUJO

    Figure 1.--Location of towns, roads, and major geographic features irrtfte; Richfield quadrangle.

  • between those values are assigned values of 70, 30,15, and so forth. The precision of the analytical method is approximately plus or minus one reporting interval at the 83 percent confidence level and plus or minus two reporting intervals at the 96 percent confidence level (Motooka and Grimes, 1976.)

    In addition, gold and antimony, arsenic, bismuth, cadmium, and zinc were determined in each sample using atomic-absorption spectrophotometry and inductively coupled plasma-atomic emission spectrometry (ICP-AES) respectively. A brief description of these procedures follows:

    Gold-A 10-gram sample is roasted for 1 hour at 700 C, gold is then digested with concentrated hydrobromic acid -0.5 percent bromine solution and extracted with MIBK (methyl isobutyl ketone. Electrothermal atomic-absorption spectrophotometry is used to determine gold to 1 ppb (O'Leary and Meier, 1986.)

    Antimony, arsenic, bismuth, cadmium, and zinc The metals of interest are solubilized from a 0.15-gram sample with hydrochloric-hydrogen peroxide solution and determined by ICP- AES. Limits of detection are antimony 2 ppm, arsenic 5 ppm, bismuth 2 ppm, cadmium 0.1 ppm, and zinc 2 ppm (Crock and others, 1987).

    The results of these analyses with the sample sites and latitude and longitude are shown in tables 2 and 3. A MF map will be published at a latter date.

    REFERENCES CITED

    Crock, J.G., Briggs, P.H., Jackson, L.L., and Lichte, F.E., 1987, Analytical methods for theanalysis of stream sediments and rocks from wilderness study areas: U.S. GeologicalSurvey Open-File Report 87-84, 35 p.

    Grimes, D.J., and Marranzino, A.P., 1968, Direct-current arc and alternating-current sparkemission spectrographic field methods for the semiquantitative analysis of geologicmaterials: U.S. Geological Survey Circular 591, 6 p.

    Motooka, J.M., and Grimes, D.J., 1976, Analytical precision of one-sixth order semiquantitativespectrographic analyses: U.S. Geological Survey Circular 738,25 p.

    O'Leary, R.M., and Meier, A.L., 1986, Analytical methods used in geochemical exploration,1984: U.S. Geological Survey Circular 948, 48 p.

    Steven, T.A., and Morris, H.T., 1984, Mineral resource potential of the Richfield 1 x 2quadrangle, west-central Utah: U.S. Geological Survey Open-File Report 84-521, 53 p.

  • Table la. Detection limits and minimum, maximum values for 181 rock analyses [Spectrographic data]

    Element No. of samples above detection limit

    Calcium (Ca)Iron (Fe)Magnesium (Mg)Sodium (Na)Phosphorus (P)Titanium (Ti)

    Silver (Ag)Arsenic (As)Boron (B)Barium (Ba)Beryllium (Be)Bismuth (Bi)Cadmium (Cd)Cobalt (Co)Chromium (Cr)Copper (Cu)Gallium (Ga)Germanium (Ge)Lanthanum (La)Manganese (Mn)Molybdenum (Mo)Niobium (Nb)Nickel (Ni)Lead (Pb)Antimony (Sb)Scandium (Sc)Tin (Sn)Strontium (Sr)Thorium (Th)Vanadium (V)Tungsten (W)Yttrium (Y)Zinc (Zn)Zirconium (Zr)

    1601711808115

    159

    342390

    169111

    00

    4796

    133994

    29179412060

    1281462

    396

    0164

    695

    1144

    Detection limits

    percent.05

    0.05.02

    0.20.2

    .002ppm

    0.5200

    1020

    11020101055

    1050105

    205

    10100

    510

    100100

    102010

    20010

    [Atomic absorption and ICP-AES

    Gold (Au)Arsenic (As)Bismuth (Bi)Cadmium (Cd)Antimony (Sb)Zinc (Zn)

    6592

    38747

    137

    Ippb5 ppm2

    .122

    Minimum value

    percent

  • Table Ib. Detection limits and minimum, maximum values for 192 stream-sediment analyses [Spectrographic data]

    Element No. of samples above detection limit

    Detection Minimum limits value

    percent percentCalcium (Ca)Iron (Fe)Magnesium (Mg)Sodium (Na)Phosphorus (P)Titanium (Ti)

    Silver (Ag)Arsenic (As)Boron (B)Barium (Ba)Beryllium (Be)Bismuth (Bi)Cadmium (Cd)Cobalt (Co)Chromium (Cr)Copper (Cu)Gallium (Ga)Germanium (Ge)Lanthanum (La)Manganese (Mn)Molybdenum (Mo)Niobium (Nb)Nickel (Ni)Lead (Pb)Antimony (Sb)Scandium (Sc)Tin (Sn)Strontium (Sr)Thorium (Th)Vanadium (V)Tungsten (W)Yttrium (Y)Zinc (Zn)Zirconium (Zr)

    191192192192

    2189

    70

    166192125

    00

    160192192192

    042

    1922

    14185192

    0186

    3188

    0192

    0192

    1191

    .050.05

    .020.20.2

    .002ppm

    .05200

    1020

    11020101055

    1050105

    205

    10100

    510

    100100

    102010

    20010

    .21

    .5

    .5

  • [N, not detected; , determined to be greater than the value shown.]

    AU PPB

    3509090

    4270580400175

    5205

    CA X