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Paleozoic Rocks Antelope Valley Eureka and Nye Counties Nevada

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Paleozoic Rocks Antelope Valley Eureka and Nye Counties Nevada :It k 'I! ' Paleozoic Rocks Antelope Valley Eureka and Nye Counties Nevada GEOLOGICAL SURVEY PROFESSIONAL PAPER 423 Paleozoic Rocks of Antelope Valley Eureka and Nye Counties Nevada By CHARLES W. MERRIAM GEOLOGICAL SURVEY PROFESSIONAL PAPER 423 P,rinciples of stratigraphy applied in descriptive study of the Central Great Basin Paleozoic column UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1963 UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary GEOLOGICAL SURVEY Thomas B. Nolan, Director For sale by the Superintendent of Documents, U.S. Government Printing Office Washington 25, D.C. CONTENTS Page Page Silurian system ____________________________________ _ Abstract------------------------------------------- 1 36 Introduction. _____________________________________ _ 2 General features-------------------------------- 36 Geologic setting ______________ ------ ___ --------- 2 Roberts Mountains formation ___________________ _ 37 History of investigation ________________________ _ 5 Lone Mountain dolomite ______ ---_-------------- 39 Purpose and scope _____________ -- ______ ------ --- 6 Devonian system ______________ ---- __ - _- ___ - _------- 41 Acknowledgments ______________________________ _ 6 General features _____________ - ___________ -_----- 41 Geologic structure as related to stratigraphy __________ _ 6 Western Helderberg age limestones of the Monitor Paleontologic studies ______ ..:. _______ ~ ________________ _ 9 · Range ______ - _.- ___ --------------------------- 42 The Paleozoic column at Antelope Valley _____________ _ 12 Rabbit Hill limestone _____ -- __ -- __ ---------- 42 Cambrian system ___________________________________ _ 14 Normal western sequence Devonian rocks of Antelope Valley ___________________ ... __________________ _ General features ___ ---- ____ -----.---- ___ -- ___ ---- 14 44 Windfall formation _____________________________ _ 14 Nevada formation ____ ..; ___ --------____ ------ 44 Ordovician system ___________________________ -·- ____ _ 16 Devils Gate limestone _____ --- ________ -- __ --- 49 General features __________ ~ ____ - _______ --------- 16 Strata of Late Devonian and Early Mississippian age __ _ 56 Pilot shale ________________ ----- _________ ---- --- Ordovician system boundaries ___________________ _ 16 56 Lower part of the Pilot shale ______ .., _________ _ Facies problems _______________________________ _ 17 56 Upper Paleozoic rocks __________ ----________ - -·------- 17 56 PogonipgrOUP---------------------------------- 56 Goodwin limestone ___________________ ------_ 19 General features-------------------------------- Ninemile formation ________________________ _ Mississippian rocks ________ ---_______ - ___ -:------ 57 22 Chainman shale and Diamond Peak formation, Antelope Valley limestone __________________ _ 23 undiffEtrentiated _____ - ---- _________ ------- 57 Copenhagen formation ____ -------______ ------ __ _ 25 Permian system _____________ - ___________ -_----- 58 Eureka quartzite ______________________________ _ 27 Garden Valley formation ________________ -- __ 58 Hanson Creek formation ________________________ _ 31 Locality register __________________ - __________ ------- 60 Western facies rocks of Ordovician age ___________ _ 33 References cited _______________ ----______ -_-_------- 61 Vinini formation ___________________________ • 33 IndeX--------------------------------------------- 65 ILLUSTRATIONS [Plates are in pocket] PLATE 1. Geologic reconnaissance map, northern half Antelope Valley area. 2. Geologic reconnaissance map, southern half Antelope Valley area. PRge FIGURE 1. Index map showing location of the Antelope Valley area-------------------------------------------------- 3 2. Index map of central and eastern Nevada-------------------------------.-------------------------------- 4 3. Section nlong line B-B' south of Ninemile Canyon, Antelope Range, showing Ordovician formations-------·---- 8 4. Section along line A-A' at Copenhagen Canyon, Monitor Range, showing thrust relationship of rocks of the Pogonip group over Lower Devonian Rabbit Hill limestone ___________ ---·---- __________________ --------- 10 5. Section along line C-C' at Ninemile Canyon, Antelope Range, showing Upper Cambrian and Ordovician forma- tions--------------------------------------------------------------------------------------------- 15 6. Correlation diagram showing possible age relationship of Ordovician rocks of Eureka and Antelope Valley, Nevada, to those of described sections in Utah---------------------------------------------------------------- 18 7. Correlation diagram showing possible age relationships of Ordovicifl,n, Silurian, and Lower Devonian rocks in the Antelope Valley area ________________________________________________________________________ -_-_--- 28 8. Correlation diagram showing probable age relationships of Devonian strata in the Antelope Valley and Eureka areas, Nevada------------------------------------------------------------------------------------- 52 TABLES Page. TABLE 1. Normal stratigraphic section at Antelope Valley, Nev---------------------------------------------------- 13 2. Comparison of normal western sequence of the Nevada formation with the eastern sequence__________________ 45 m PALEOZOIC ROCKS OF ANTELOPE VALLEY,' EUREKA AND NYE COUNTIES, NEVADA 'Ry CHARLES w. ~fERRIAl\[ ABSTRACT '.rhe normal Ordovician column including six formations is about 4,300 feet thick. Ranging in age from Early to Late Antelope Valley is bordered by mountains of the Basin and Ordovician (Richmond), these units are in order from bottom Unnge Province thnt consist mainly of Paleozoic strata partly to top as follows : Goodwin limestone, Ninemile formation, covered by Cenozoic volcnnic rocks. The Paleozoic beds range Antelope Valley limestone, Copenhagen formation, Eureka in age from r... nte Cambrian to Jilnrly Permian; only the Pennsyl­ quartzite, and Hanson Creek formation. Limestones predomi­ vanian system is unrecognized. nate, but the Eureka quartzite is a notable exception. Three Reconnaissanee geologic mapping in the 1-degree Roberts of these Ordovician formations-Ninemile, Antelope Valley, Mountains quadrangle pointed up need for special studies of and Copenhagen-have type sections in the Antelope Valley stratigraphy nnd paleontology relating principally to the Ordo­ area. The richly fossiliferous .Copenhagen, theoretically a vician, Silurian, nnd Devonian systems. facies of the lower part of the Eureka, is known only in the Widespread thrusting coupled with Inter normal faulting so study area. _ complicates stratigraphie study in this region that n simul­ Thrust outliers of Ordovician graptolite shale, bedded chert, taneous approach to problems of stratigraphy and structural and sandstone occur in the northern Mahogany Hills, at the geology is needed. To achieve n more comprehensive regional - north end of Monitor Range, and in the vicinity of Charnac understanding of nreal, stratigraphic, and structural relations, Basin. Where fossils are absent, these shales and sandstones the Antelope Valley investigations were coordinated with work of the Vinini are easily confused with similar beds of Carbonif- . in the adjoining Eureka mining district. erous age. Impressive manifestations of intense deformation nre thrust The rocks of the Silurian system, about 2,200 feet thick, in­ outliers of Ordovician beds of the . Vinini formation. These clude the Roberts Mountains formation below and the Lone outliers rest upon Paleozoic rocks of dift'erent facies and range MountaiQ dolomite above. Limestone of the Roberts Moun­ in nge from Ordovician to Carboniferous. It has become reason­ tains formation carries a Monograptus fauna in the Monitor ably certain thnt the graptolitic rocks were deposited in a west­ Range ; its base is there defined by a laterally persistent cherty ern Great Basin depositional subprovince, whereas the pre-. zone. This formation changes to dolomite on the east side of Carboniferous rocks over which they hnve been thrust accumu­ Ant~lope Valley, where it is gradati'onal above with the Lone lated in nn eastern subprovince wherein carbonate sedimenta­ Mountain dolomite. In the Monitor Range, where the Lone tion predominated. Immense horizontal displacement is clearly Mountain .is unrecognized, the llfonograptus beds are seemingly related to the Roberts Mountains thrust, earlier described in overlain disconformably by Early Devonian (Helderberg) Rab- the region to the north. Thrusts of lower magnitude in the bit Hill limestone. · Monitor nnd Antelope ranges nre possibly sympathetic to the main Roberts Mountains thrust. Silicified . fossils, inciuding the Late Silurian brachiopod Aside from the major facies changes. of subprovincial mag­ H o'Wellella, occur in the upper part of the Lone Mountain nitude, well-marked east-west differences are recognized within dolomite. These beds are disconformably overlain by .Oriskany Ordovician, Silurian, and Devonian rocks of the eastern or age Lower Devonian dolomitic limestone of the Nevada on the carbonate subprovince itself. east side of Antelope Valley. Of 17 Paleozoic formations deseribed in this report 14 are Devonian rocks of this area, about 4,000 feet thick, range normally superposed nt Antelope Valley. These r~nge from in age from Helderberg to Late Devonian and are classified in Lnte Cnmbrinn to Mississippian. The Ordovician is the most four formations; only three of them-the Nevada, the .Devils diverse in terms both of rock type and faunas. Twelve of the Gate, and the lower part of
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