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Title: Absolute age constraints on the age and tectonics of the Middle and Late Proterozoic Pahrump Group, southern Death Valley, California

Abstract

The Pahrump Group unconformably overlies 1.35 Ga granite, is unconformably overlain by the Late Proterozoic Noonday Dolomite, and is divided into the Crystal Spring Formation, the Beck Spring Dolomite, and the Kingston Peak Formation. Contacts between these formations are gradational through several meters of interbedded clastic and carbonate rocks. Lithologic data, sedimentary structures, and fossil assemblages suggest that the Pahrump Group, from middle Crystal Spring to lower Kingston Peak time, was deposited in an intratidal to supratidal environment. Diamictite, volcanic ash, and mono lithologic megabreccia suggest that the middle and the upper members of the Kingston Peak Formation were deposited in a higher energy sedimentary and tectonic environment. Dikes and sills of 1.08 Ga diabase intrude the gneiss and all members of the Crystal Spring Formation; erosional clasts of diabase first appear in the middle Kingston Peak Formation. The diabase sills are up to 450 m thick and have caused at least 20 percent inflation of the Crystal Spring, Beck Spring, and lower Kingston Peak formations. If these sedimentary rocks were deposited at or above wave base, evidence of intraplate rifting or gross stratigraphic inflation is not recorded in the Pahrump stratigraphy until middle and upper Kingston Peak time. Therefore,more » the stratigraphic and petrologic data suggest that the diabase was emplaced in the Crystal Spring Formation during post-lower but pre-middle Kingston Peak time. The Beck Spring Dolomite and the lower Kingston Peak Formation are older than 1.08 Ga; the contact between the lower and the middle Kingston Peak Formation is a regional disconformity that marks significant changes in the depositional and the tectonic environments of the Pahrump Group at about 1.08 Ga.« less

Authors:
 [1];
  1. (Geological Survey, Menlo Park, CA (United States))
Publication Date:
OSTI Identifier:
5342684
Report Number(s):
CONF-9305259--
Journal ID: ISSN 0016-7592; CODEN: GAAPBC
Resource Type:
Conference
Resource Relation:
Journal Name: Geological Society of America, Abstracts with Programs; (United States); Journal Volume: 25:5; Conference: 89. annual meeting of the Cordilleran Section and the 46th annual meeting of the Rocky Mountain Section of the Geological Society of America (GSA), Reno, NV (United States), 19-21 May 1993
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; CALIFORNIA; GEOLOGIC FORMATIONS; AGE ESTIMATION; GEOLOGY; DIABASES; DIKES; GEOLOGIC HISTORY; PRECAMBRIAN ERA; TECTONICS; BASALT; DEVELOPED COUNTRIES; GEOLOGIC AGES; GEOLOGIC STRUCTURES; IGNEOUS ROCKS; NORTH AMERICA; ROCKS; USA; VOLCANIC ROCKS 580000* -- Geosciences

Citation Formats

Calzia, J.P., and Troxel, B.W.. Absolute age constraints on the age and tectonics of the Middle and Late Proterozoic Pahrump Group, southern Death Valley, California. United States: N. p., 1993. Web.
Calzia, J.P., & Troxel, B.W.. Absolute age constraints on the age and tectonics of the Middle and Late Proterozoic Pahrump Group, southern Death Valley, California. United States.
Calzia, J.P., and Troxel, B.W.. 1993. "Absolute age constraints on the age and tectonics of the Middle and Late Proterozoic Pahrump Group, southern Death Valley, California". United States. doi:.
@article{osti_5342684,
title = {Absolute age constraints on the age and tectonics of the Middle and Late Proterozoic Pahrump Group, southern Death Valley, California},
author = {Calzia, J.P. and Troxel, B.W.},
abstractNote = {The Pahrump Group unconformably overlies 1.35 Ga granite, is unconformably overlain by the Late Proterozoic Noonday Dolomite, and is divided into the Crystal Spring Formation, the Beck Spring Dolomite, and the Kingston Peak Formation. Contacts between these formations are gradational through several meters of interbedded clastic and carbonate rocks. Lithologic data, sedimentary structures, and fossil assemblages suggest that the Pahrump Group, from middle Crystal Spring to lower Kingston Peak time, was deposited in an intratidal to supratidal environment. Diamictite, volcanic ash, and mono lithologic megabreccia suggest that the middle and the upper members of the Kingston Peak Formation were deposited in a higher energy sedimentary and tectonic environment. Dikes and sills of 1.08 Ga diabase intrude the gneiss and all members of the Crystal Spring Formation; erosional clasts of diabase first appear in the middle Kingston Peak Formation. The diabase sills are up to 450 m thick and have caused at least 20 percent inflation of the Crystal Spring, Beck Spring, and lower Kingston Peak formations. If these sedimentary rocks were deposited at or above wave base, evidence of intraplate rifting or gross stratigraphic inflation is not recorded in the Pahrump stratigraphy until middle and upper Kingston Peak time. Therefore, the stratigraphic and petrologic data suggest that the diabase was emplaced in the Crystal Spring Formation during post-lower but pre-middle Kingston Peak time. The Beck Spring Dolomite and the lower Kingston Peak Formation are older than 1.08 Ga; the contact between the lower and the middle Kingston Peak Formation is a regional disconformity that marks significant changes in the depositional and the tectonic environments of the Pahrump Group at about 1.08 Ga.},
doi = {},
journal = {Geological Society of America, Abstracts with Programs; (United States)},
number = ,
volume = 25:5,
place = {United States},
year = 1993,
month = 4
}

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  • Deposition of the Pahrump Group rocks (Crystal Spring-Beck Spring-Kingston Peak Formations) in the Death Valley region of California post-dates 1.7 to 1.4 Ga gneissic basement rocks (Wright et al., 1976) and mostly predates the inferred 0.75 Ga glacial deposits of the Kingston Peak Formation. The 1.08 Ga age of the diabase sills in the middle Crystal Spring Formation provides an additional time constraint. Event though this time span is excessive when compared to better dated Phanerozoic successions, the Pahrump Group, nonetheless, has been assumed to be internally conformable. Results from the authors recent work invalidates that assumption. They have carefullymore » measured 15 sections of upper member Crystal Spring Formation rocks and have mapped in detail the belt of exposures in the Saratoga, Saddle Peak, and Ibex Hills, and northern Kingston Range. Their data indicates that an unconformity of significant but unknown duration occurs within the upper member. Evidence for this unconformity includes: (1) local angular discordance of up to 20[degree]; (2) presence of an erosive-based breccia unit (0.10--30 m thick) that consists mostly of hornfelsic clasts derived from immediately subjacent rocks; and (3) erosional beveling and truncation of underlying rocks. In addition, the upward transition to Beck Spring deposition is marked by a disconformity (sequence boundary) that cuts down across and erosionally truncates strata of the upper member Crystal Spring Formation.« less
  • The Lake Superior Oronto Group and the Grand Canyon Chuar Group are the most significant Precambrian hydrocarbon targets within the conterminous United States. These frontier terrains share common Proterozoic age, comparable total organic carbon source rock values, association with Indian-interest properties, plus similarities in reservoir, trap, and maturation characteristics. Extensively studied since 1980, the exploration philosophy applied to the Oronto Group is presented as a model for Chuar Group hydrocarbon evaluation. Hydrocarbon shows have been reported since 1852 from middle Proterozoic rocks of the Lake Superior basin. Occurrences include stains within stromatolitic facies of the Copper Harbor Conglomerate, live subsurfacemore » seeps within Nonesuch units in the White Pine copper mine of Michigan, and impsonite-like inclusions within calcite veins of the Freda Formation. These formations compose the Oronto Group, a synrift package infilling the Lake Superior basin of the mid-continent rift system. Seep analyses identify a low sulfur (0.02%), paraffinic (67%), 34 API crude indirectly dated (Rb/Sr) at a minimum of 1047{plus minus}35 Ma. Nonesuch Formation source shales are present within both central horst structures and flank half-grabens. Reservoir-quality criteria are associated with adjacent Copper Harbor and overlying Freda Formation units. Seismically identified traps range from anticlinal and drag folding to onlap, stratigraphic, and unconformity closures. The Lake Superior segment of the mid-continent rift system is subdivided into four structural units (I-IV). Association of oil seeps with stratiform copper deposits (unit III) suggests evidence of geochemical symbiosis. This crude entered oil-window status circa 1.0 Ga due to migrating cupriferous thermal systems.« less
  • The Midcontinent rift system forms one of the most prominent gravity features in North America. The geophysical anomaly extends in an arc from Oklahoma to Lake Superior and then into Kentucky. The Midcontinent Rift System was active between 1.19--1.01 Ga as indicated in the Lake Superior region by age dating of intrusive igneous rocks. The authors suggest that the period of formation of the Midcontinent rift was a time of extensive igneous activity in Texas and New Mexico which is represented by intrusions beneath the Central Basin Platform (TX-NM), Pajarito Mountain in the Sacramento Mountains (NM), the Mundy Breccia inmore » the Franklin Mountains (TX), lava flows in the Allamore Formation near Van Horn (TX), and the Crosbyton geophysical anomaly (east of Lubbock, TX). These bodies were intruded between 1.07--1.22 Ga. These bodies and other bodies located by geophysical anomalies and wells drilled into mafic Precambrian rocks may be related to the Midcontinent rift system by a rift jump or splay. Alteratively this magmatism could be related to Grenville age tectonics in Texas. The Central Basin Platform, is divided in two on gravity maps by the Abilene minimum, an ENE trending 900 km long 100 km wide gravity low. This gravity low is not associated with basement topography and must be an intra-basement feature. One possible source of this body is a continental arc batholith. This batholith must have been intruded near a suture zone prior to 1166 Ma the age of the Central Basin Platform intrusion. A possible age for this intrusive would be 1,350--1,400 Ma. This age would coincide with formation of the Chaves Granite Gneiss terrain and the Red River-Tillman metamorphic belt, a possible foreland basin. This date would also coincide with regional metamorphism in north-central New Mexico.« less
  • Late Proterozoic through Lower Cambrian rocks in the southern Great Basin form a westward-thickening wedge of predominantly clastic deposits that record deposition on the early western shelf edge of western North America (Stewart and Poole, 1974; Poole and others, 1992). Regional analyses of geologic controls on ground-water flow in the southern Great Basin typically combined lithostratigraphic units into more general hydrogeologic units that have considerable lateral extent and distinct hydrologic properties. The Late Proterozoic through Lower Cambrian rocks have been treated as a single hydrogeologic unit, named the lower clastic aquitard (Winograd and Thordarson, 1975) or the quartzite confining unitmore » (Laczniak and others, 1996), that serves as the hydrologic basement to the flow system. Although accurate in a general sense, this classification ignores well-established facies relations within these rocks that might increase bedrock permeability and locally influence ground-water flow . This report presents a facies analysis of Late Proterozoic through Lower Cambrian rocks (hereafter called the study interval) in the Death Valley regional ground-water flow system - that portion of the southern Great Basin that includes Death Valley, the Nevada Test Site, and the potential high-level nuclear waste underground repository at Yucca Mountain (fig. 1). The region discussed in this report, hereafter called the study area, covers approximately 100,000 km2 (lat 35 degrees-38 degrees 15'N., long 115 degrees-118 degrees W.). The purpose of this analysis is to provide a general documentation of facies transitions within the Late Proterozoic through Lower Cambrian rocks in order to provide an estimate of material properties (via rock type, grain size, and bedding characteristics) for specific hydrogeologic units to be included in a regional ground-water flow model.« less
  • Paleomagnetic results from Proterozoic intrusive rocks from the central and southern Rocky Mountains yield data that provide definition to the North American APW path. Results from the ca. 1420 Ma Laramie anorthosite (LA) and Sherman Granite (SG) yield dual polarity magnetizations; a combined pole (7[degree]S, 215[degree]E, A[sub 95] = 4[degree]) is essentially identical to 1400 Ma poles from elsewhere in North America. Group A dikes from the Tobacco Root (TR) Mtns, MT, along the southern margin of the Belt Basin, have a dual-polarity remanence with a pole at 10[degree]N, 222[degree]E (A[sub 95] = 11[degree]) that plots slightly north of themore » LA/SG and other poles of ca. 1450 Ma. Comparison of Belt Supergroup poles, assuming coherence of the Belt terrane and interior Laurentia, with 1400 Ma poles and those of the well-defined western arm of the Logan Loop of the N. American APW path, would seem to indicate that the age of most Belt poles are in the range of 1300--1400 Ma, although this age assignment conflicts with available geochronologic data. Results from 1100 Ma diabase sheets from central AZ yield two distinct, normal and reverse polarity magnetizations: ADn and ADr. ADn gives a pole at 23[degree]N, 181[degree]E (A[sub 95] = 8[degree]) that overlaps poles of ca. 1100 Ma from the midcontinent rift (MR). Pole ADr is located at 38[degree]N, 248[degree]E (A[sub 95] = 39[degree]); the large uncertainty of this pole precludes its use in defining the APW path. All dikes are of WNW trend and several from the TR Mtns and the Christmas Lake dike from the Beartooth uplift give hornblende [sup 40]Ar/[sup 39]Ar ages of 760--770 Ma. The data are interpreted to provide evidence for Late Proterozoic mafic magmatism along the W and SW margin of the Wyoming Province, possibly related to crustal extension accompanying deposition of the Windermere Group in the northern part of the Cordillera and volcanism and sedimentation in SE Idaho and NE Washington.« less