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Olistostrome shed eastward from the Antler orogenic forebulge, Bisoni-McKay area, Fish Creek Range, central Nevada

Forrest G. Poole and Charles A. Sandberg
Olistostrome shed eastward from the Antler orogenic forebulge, Bisoni-McKay area, Fish Creek Range, central Nevada (in Unusual central Nevada geologic terranes produced by Late Devonian Antler Orogeny and Alamo Impact, Forrest G. Poole (editor) and Charles A. Sandberg (editor))
Special Paper - Geological Society of America (September 2015) 517

Abstract

The Bisoni-McKay area, a structurally isolated, fault-bounded horst, offset eastward at the south end of the Fish Creek Range, displays a geologic terrane that is previously unrecorded in Nevada, and perhaps elsewhere in North America. This unique terrane is an olistostrome that was shed eastward by listric faulting from the east side of the migrating Antler orogenic forebulge in Late Devonian (early Famennian, ca. 373 Ma) time. Stratigraphic identification of Devonian olistoliths and enclosing matrix that constitute the olistostrome, as well as overlying postemplacement units, is supported by correlation to formations in the main part of the Fish Creek Range and to the northwest in the northern Antelope Range. Precise zonal dating of map units and revised dating of Antler orogenic events are provided by 38 conodont collections recorded in the Devonian/Carboniferous (D/C) Conodont Database and by small collections of conodonts embedded in siltstone and mudstone. Our revision of regional geologic history uses Devonian conodont zones to measure "deep time" to circa millions of years before present. The upper Upper Devonian (Famennian) tongue of the Woodruff Formation was deposited directly on the olistostrome and is overlain by clastic Mississippian synorogenic deposits. These deposits were shed eastward from the evolving Antler highland and related Roberts Mountains allochthon into the Antler foredeep. We propose the following revised dates for important Devonian tectonic events in Nevada: initiation of Antler orogeny, ca. 385 Ma; downwarping of Pilot backbulge basin, ca. 382 Ma; initial uplift of the Antler highland, ca. 373 Ma; third, major pulse of highland uplift, ca. 364 Ma. A summation of regional geologic history indicates that the elapsed time from start of Antler orogeny to start of Roberts Mountains thrusting was approximately 30 m.y.


ISSN: 0072-1077
EISSN: 2331-219X
Coden: GSAPAZ
Serial Title: Special Paper - Geological Society of America
Serial Volume: 517
Title: Olistostrome shed eastward from the Antler orogenic forebulge, Bisoni-McKay area, Fish Creek Range, central Nevada
Title: Unusual central Nevada geologic terranes produced by Late Devonian Antler Orogeny and Alamo Impact
Author(s): Poole, Forrest G.Sandberg, Charles A.
Author(s): Poole, Forrest G.editor
Author(s): Sandberg, Charles A.editor
Affiliation: U. S. Geological Survey, Denver, CO, United States
Affiliation: U. S. Geological Survey, Denver, CO, United States
Published: 20150911
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 50
Accession Number: 2016-024724
Categories: Economic geology, general, depositsSedimentary petrology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Includes appendices
Illustration Description: illus. incl. 4 tables, geol. sketch maps
N36°00'00" - N39°07'60", W118°15'00" - W115°00'00"
Source Note: Online First
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201613
Program Name: USGSOPNon-USGS publications with USGS authors
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