Fluvial Depositional Styles and FluvialÆLacustrine …•Fluvial deposits within the Passaic...
Transcript of Fluvial Depositional Styles and FluvialÆLacustrine …•Fluvial deposits within the Passaic...
Med
.
Fine
V. F
ine
Silt
Cla
y
1
2
3
4
5
6
10
9
8
7
15
14
13
12
11
18
19
17
16
20
1
6
2
3
5
9
8
7
11
17
15
14
21
19
18
Med
.
Fine
V. F
ine
Silt
Cla
y
1
2
3
4
5
6
10
9
8
7
15
14
13
12
11
18
19
17
16
20
1
6
2
3
5
9
8
7
11
17
15
14
21
19
18
Metlars M
ember
Livingston Mem
ber
Trough Crossbeds / Laminations
Carbonate Nodules
M
Tabular Crossbeds/laminations
Massive BeddingClimbing Current RipplesScour
Desiccation Cracks
Horizontal BurrowsVertical BurrowsRoot CastsPlanar Laminations
Surface Ripples
Soft Sediment Deformation
Mud Chips
Wavy Bedding
Fluvial Depositional Styles and Fluvial Lacustrine Transition Zones of the Passaic Formation, Newark Basin. Joshua H. Long, Dr. S.J. Friedmann
Med
.
Fine
V. F
ine
Silt
Cla
y
1
2
3
4
5
6
10
9
8
7
15
14
13
12
11
18
19
17
16
24
23
22
21
20
26
25
27
1
6
7
2
4
3
5
8
13
10
9
12
11
14
15
18
17
16
19
21
20
2223
24
26
25
2728
2930313233
34
35
3736
3839
41 40
42
43441 4444
4
6
5
7
8
91011
12
14
13
15
Roadside Q
uarry
M
M
M
M
Depth (m)
Med
.
Fine
V. F
ine
Silt
Cla
y
1
2
3
4
5
6
10
9
8
7
15
14
13
12
11
18
19
17
16
24
23
22
21
20
26
25
27
1
6
7
2
4
3
5
8
13
10
9
12
11
14
15
18
17
16
19
21
20
2223
24
26
25
2728
2930313233
34
35
3736
3839
41 40
42
43441 4444
4
6
5
7
8
91011
12
14
13
15
Roadside Q
uarry
M
M
M
M
Depth (m) Roadside Q
uarry (2)R
ailroad Cut (1)
Railroad Cut (Upper), Location #1
a) b) c)
a) Mud draped tabular sandbeds. b) Climbing current ripples, planar laminations. c) Thin intervening mud beds.
Pebbles Bluff, Location #4
Grain Size Trends
0
200
400
600
800
1000
1200
1400
1600
1800
Mud Silt VeryFine
Lower
VeryFine
Upper
FineLower
Fineupper
MediumLower
Grain SIze
Cum
ulat
ive
Thic
knes
s (c
m)
Railroad cutRaodside quarryTrap RockPebbles BluffSomerset Core
Grain Size
Cum
ulative Thickness (cm)
Abstract The sediments within the Newark Basin contain a record of cyclic deposition at multiple frequencies. Due to their pronounced cyclicity and climatic sensitivity the lacustrine deposits within the basin have been the focus of many basin studies. While the lake deposits are well documented, relatively little is known about the fluvial systems that carried water and sediments to these ancient lakes. Locally, fluvial sediments can be coarse- grained and channelized, and are believed to represent deposition in coarse-grained braided systems, notably in the Stockton and Passaic. Such deposits can be limited to areas proximal to the main border fault system and were noted for this project in the Pebbles Bluff exposure of the LM Member of the Passaic Formation. However, there are many relatively fine-grained, thin-bedded sandy fluvial deposits that show little evidence for channeling and amalgamation. The system evolves through nodal avulsion and the construction of crevasse and terminal splays. Outcrop observations of the Metlars and Livingston Members of the Passaic Formation show that the non-lacustrine, relatively coarser grained facies are dominated by extensive tabular sandsheets whose geometries, structures and range of grain sizes are consistent with deposition in anastomosed fluvial networks, similar to those of the Okavango Delta in Botswana. The Okavango lies within a half-graben in the southernmost extension of the East African Rift system. Paleogeographic reconstructions, using paleomagnetic and paleoclimatic data taken from lacustrine deposits, have placed the Newark Basin at roughly 20°north latitude during the late Triassic and early Jurassic, which is similar in climate to the 20°south latitude position of the present-day Okavango. As such, the Okavango may serve as a general analog for the fluvial members of the Passaic Formation in terms of hydrology and architectural evolution.
Methods
•Data collected in the field compiled in the form of measured sections.
•Photopan analyses.
•Core observations
Hypotheses
Coarse grained facies within the Passaic Formation are:
•Dominated by braided streams
•Dominated by anastomosed streams
•Exhibit characteristics of both braided and anastomosed streams
Conclusions
•Fluvial deposits within the Passaic exhibit structures, geometries and characteristics of meandering, braided and anastomosed fluvial depositional systems.
Interpretations
•Locations 1 &2: Proximal & Distal Lacustrine Deltaic Deep, Perennial Lacustrine Missing Interval (?) Anastomosed Crevasse Splay Deposits Shallow, Ephemeral Lacustrine Lacustrine Deltaic Deep,Perrenial Lacustrine.
•Location 4: Meandering Fluvial Shallow, Ephemeral Lacustrine Lacustrine Deltaic
Somerset #1 Core
Six sub environments of anastomosed systems (Smith &Putnam, 1980):1. Backswamp: Organic silty mud. 2. Peat Bog: Variable amounts of organic debris.3. Ephemeral Floodpond: Very fine grained laminated and wave rippled lacustrine sediments with
Mudcracked exposure surfaces.4. Channel: Shallow, low relief sand lenses. Often contain climbing ripples and planar-crossbeds.5. Levee systems: Variable amounts of organic material.6. Crevasse: Laterally extensive, tabular sand sheets up to 1 meter thick. Constitute the bulk of
the silt sand size component of anastomosed systems. Structures include, climbing current ripples, planar bedding/laminations and wave rippled mud surfaces indicating submergence in shallow water after deposition in deccelerative flow (Naydon, 1994)..
-Nadon 1994
Okavango River, Botswana
Channel
Crevasse Splay Sands
Flood Pond
Epsilon Crossbeds
Med
.
Fine
V. F
ine
Silt
Cla
y
1
2
3
4
5
6
10
9
8
7
14
13
12
11
10
1
3
2
4
M
M
11
14
1213
18
15
17
19
20
2223
21
31
2524
M
M
M
Med
.
Fine
V. F
ine
Silt
Cla
y
1
2
3
4
5
6
10
9
8
7
14
13
12
11
10
1
3
2
4
M
M
11
14
1213
18
15
17
1919
2020
2223
21
31
2524
MM
M
MM
Pebbles Bluff (4)Red Strata
Gray Strata
Purple Strata
Field Locations 1, 2, 3
Pebbles Bluff Location
Somerset Core
-Olsen et al., 1996
Deltaic TurbiditesCurrent Ripples
Planar Bedding
Massive bedding Shallow Lacustrine Muds
Roadside Quarry, Location #2
a) b)
a) Tabular crossbeds overlain by planar laminations
b) Polygonal desiccation cracks.
Railroad Cut (Middle), Location #1
a) b) c)
a) Desiccation cracks b) Soft sediment deformation c) Root casts
References
Nadon, G.C. The Genesis and Recognition of Anastomosed Fluvial Deposits:Data From the St. Mary’s River Formation, South Western Alberta, Canada. Journal of Sedimentary Research. Vol.B64, No. 4
Olsen, P.E., Kent, D.V., Cornet, B., Witte, W.K., Schlische, R.W., High-Resolution Stratigraphy of the Newark Basin. Geological Society of America Bulletin: January 1996; Vol. 108; no. 1;p. 40-77.
Smith, D.G., Putnam, P.E. Anastomosed River Deposits; Modern and Ancient Examples in Alberta, Canada. National Research Council of Canada. 008-4077/80/101396
Acknowledgements
Dr. S. J. Friedmann for his support and guidance.
Dr. Jim Browning, Dr. Roy Schlische and their graduate students at Rutgers University for their help with the Newark Basin cores.
Dr. Phil Candela and Dr. John Merck
Laura Gilbert for her help in the field.
Field Locations 1, 2, 3
Pebbles Bluff Location
-www.lib.utexas.edu
-www.e-gnu.com