Two facies of lower Paleozoic rocks
There are two principalPlate tectonics
From an early date, geologists have struggled to explain the presence in Nevada and adjacent areas of the Antler orogenic deposits without achieving a consensus. The advent ofPresent knowledge
This much is known concerning the Antler orogeny: # Great volumes ofOrigin of terminology
Based on stratigraphic relations near Antler Peak, of the Battle Mountains, Roberts introduced the term Antler orogeny in an abstract as follows: ''The earliest orogeny, here named the Antler orogeny ... took place during Mississippian (?) and early Pennsylvanian time.'' That abstract was followed in 1951 by his geologic map of the Antler Peak quadrangle in the text of which he described the Antler orogeny in detail and somewhat refined its age span: ''During the Antler orogeny, formations in Battle Mountain ranging in age from Ordovician to Mississippian (?) were complexly folded and faulted. As these rocks are unconformably overlain by the Battle Formation of Early Pennsylvanian (Des Moines) age, the orogeny probably took place during the Late Mississippian. The orogeny may have continued into Early Pennsylvanian, however, for the coarse conglomerates of the Battle Formation indicate derivation from a rugged highland area.'' In a subsequent influential paper, Roberts and others adjusted the age of the Antler orogeny as follows: ''This belt is now known to have been the locus of intense folding and faulting during the Antler orogeny in latest Devonian or Early Mississippian time ...'' In the same paper the authors established a connection between the Antler orogeny and a major thrust fault as follows: ''A belt along the 116°-118° meridians—the Antler orogenic belt—was the locus of intense folding and faulting that culminated in the Roberts Mountains thrust fault...'' That age range and connection with the Roberts Mountains thrust were confirmed in a widely quoted paper by Silberling and Roberts: ''During the Late Devonian or Early Mississippian ... the Antler orogenic belt was intensely folded and faulted, and during Mississippian time the Roberts Mountains thrust sheet was emplaced.'' The effect of this revision in the age of the orogeny was to exclude the evidence in the Antler Peak quadrangle cited above for a Late Mississippian to mid-Pennsylvanian age, on which the concept of the Antler orogeny originally had been based, and to establish the conventional age of that orogeny as Late Devonian to Early Mississippian. The original date of the Roberts Mountains thrust fault was post-Paleozoic. However, with publication of the 1958 and 1962 papers cited above, the authors revised the age of the Roberts Mountains thrust to coincide with the Late Devonian to Mississippian Antler orogeny and to extend the name far beyond theTheories
Over a period of 22 years numerous reports relating the Antler orogeny and Roberts Mountains thrust to plate convergence were published in various journals, and because their basic tenets have been widely accepted, they are here termed the conventional theories. The earliest effort to relate plate tectonics specifically to the Antler orogeny was briefly outlined by E.M. Moores: ''A collision of this continental margin with a subduction zone dipping away from it in late Devonian-early Mississippian time ... resulted in deformation of the pre-existing continental marginal rocks in the Antler Orogeny.'' Two principal contrasting tectonic theories were published in greater detail between 1972 and 1992 as related below. One theory involved closure of aEast-dipping subduction
Burchfiel and Davis presented the first detailed paper that explained the Antler orogeny and the Roberts Mountains thrust in terms of the subduction aspect of plate tectonics, stating: ''... the paleogeography of this part of the Cordilleran geosyncline probably consisted of an offshore island complex separated from the continental slope and shelf by a small ocean basin of behind-the-arc type. Initial regional deformation within the Cordilleran geosyncline—the Mid-Paleozoic Antler orogeny—was characterized by the eastward displacement (Roberts Mountains thrust) of eugeosynclinal units from within the small ocean basin over miogeosynclinal strata deposited on the continental shelf.'' Their now-outdated terms ''eugeosynclinal'' and ''miogeosynclinal'' refer respectively to the western facies and eastern facies domains. In that paper, Burchfiel and Davis set the parameters for future discussions of the nature and origins of the Antler orogeny and associated thrusts. Their basic concept of east-dipping subduction was reflected in modified form by others, including Miller and others.West-dipping subduction
Dickinson and others argued for an opposing theory, that west-dipping subduction and volcanicStrike-slip faulting
As an alternative to the two conventional theories described above, Ketner proposed that ''(1) left-lateral strike-slip faulting along the western margin of the North American continent, rather than plate convergence, was the engine of Paleozoic tectonics in the region; (2) the Roberts Mountains allochthon, as such, does not exist, and the Ordovician to Devonian western facies assemblage was deposited essentially in situ; and (3) blocks of shelf carbonate rocks earlier thought to be exposures of the shelf in windows of the Roberts Mountains allochthon are slide blocks from the carbonate shelf. The slide blocks probably were dislodged by the Alamo impact event of Late Devonian age.'' In this scheme, the deep-water aspects of the western facies assemblage are due to sea-level rise in the Cambrian rather than displacement from an ocean basin. The sedimentary effects of the Antler orogeny are well known and well described in many published reports, but the exact nature of that event and the driving force remain unsettled. Among the unanswered questions are these: what aspect of plate tectonics was involved; what effect did the Alamo impact event have; why did marine basins appear in the area of general uplift; why did the western facies assemblage, and not the eastern assemblage, include bedded chert, basaltic bodies, barite deposits, and sulfide deposits.References
{{reflist, 33em, refs= {{Cite journal, last1=Burchfiel, first1=B.C., last2=Davis, first2=G.A., year=1972, title=Structural framework and evolution of the southern part of the Cordilleran orogen, western United States, journal=American Journal of Science, volume=272, pages=97–118, doi=10.2475/ajs.272.2.97, issue=2, bibcode=1972AmJS..272...97B {{Cite book, last1=Burchfiel, first1=B.C., last2=Cowan, first2=D.S., first3=G.A., year=1992, chapter=Tectonic overview of the Cordilleran orogen in the western United States, editor1-last=Burchfiel, editor1-first=B.C., editor2-last=Lipman, editor2-first=P.W., editor3-last=Zoback, title=The Cordilleran orogen—Conterminous U.S., location=Boulder, Colo., publisher=Geological Society of America, series=Decade of North American Geology, The Geology of North America, volume=G-3, pages=407–480, last3=Davis, editor3-first=M.L., isbn=978-0813752174 {{cite journal, last=Crafford, first=A.E.J., title=Paleozoic tectonic domains of Nevada: An interpretive discussion to accompany the geologic map of Nevada, journal=Geosphere, date=February 2008, volume=4, pages=260–291, doi=10.1130/GES00108.1, issue=1, url=http://geosphere.geoscienceworld.org/content/4/1/260.abstract, bibcode=2008Geosp...4..260J, doi-access=free {{cite book, last=Dickinson, first=W.R., title=Paleozoic plate tectonics and the evolution of the Cordilleran continental margin, editor1-first=J.H, editor2-last=Stevens, editor2-first=C.H., publisher=Pacific Section of the Society of Economic Paleontologists and Mineralogists, series=Pacific Coast Paleogeography Symposium, volume=1, date=April 22, 1977, pages=137–155, editor1-last=Stewart, work=Paleozoic paleogeography of the western United States, url=http://archives.datapages.com/data/pac_sepm/019/019001/pdfs/137.htm {{cite journal, last1=Dickinson, first1=W.R., last2=Harbaugh, first2=D.W., last3=Saller, first4=A.H., last5=Snyder, first5=P.L., last6=Snyder, first6=W.S., year=1983, title=Detrital modes of upper Paleozoic sandstones derived from Antler orogen in Nevada—Implications for nature of Antler orogeny, journal=American Journal of Science, volume=283, pages=481–509, doi=10.2475/ajs.283.6.481, first3=A. H., last4=Heller, issue=6, bibcode=1983AmJS..283..481D {{cite journal, last1=Harbaugh, first1=D.W., last2=Dickinson, first2=W.R., year=1981, title=Depositional facies of Mississippian clastics, Antler foreland basin, central Diamond Mountains, Nevada, journal=Journal of Sedimentary Petrology, volume=51, pages=1223–1234, issue=4, url=http://jsedres.geoscienceworld.org/content/51/4/1223.short {{cite journal, last1=Johnson, first1=J.G., last2=Pendergast, first2=A., year=1981, title=Timing and mode of emplacement of the Roberts Mountains allochthon, Antler orogeny, journal=Geological Society of America Bulletin, volume=92, pages=648–658, issue=1, bibcode=1981GSAB...92..648J, doi=10.1130/0016-7606(1981)92<648:TAMOEO>2.0.CO;2 {{cite book, last=Ketner, first=K.B., year=2012, title=An alternative hypothesis for the mid-Paleozoic Antler orogeny in Nevada, publisher=U.S. Geological Survey, id=Professional Paper 1790, url=http://pubs.usgs.gov/pp/1790/PP1790_508.pdf {{cite book, last=Ketner, first=K.B., year=2013, title=Stratigraphy of lower to middle Paleozoic rocks of northern Nevada and the Antler orogeny, publisher=U.S. Geological Survey, id=Professional Paper 1799, url=http://pubs.usgs.gov/pp/1799/ {{Cite book, last=Lochman-Balk, first=Christina, year=1972, chapter=Cambrian System, editor-last=Mallory, editor-first=W.W., publisher=Rocky Mountain Association of Geologists, pages=60–75, title=Geologic atlas of the Rocky Mountain region, oclc=123201439 {{cite journal, last1=Merrian, first1=C.W., last2=Anderson, first2=C.A., year=1942, title=Reconnaissance survey of the Roberts Mountains, Nevada, journal=Geological Society of America Bulletin, volume=53, issue=12_1, pages=1675–1726, doi=10.1130/gsab-53-1675 , url=http://gsabulletin.gsapubs.org/content/53/12_Part_1/1675.short, bibcode = 1942GSAB...53.1675M {{cite journal, last1=Miller, first1=E.L., last2=Holdsworth, first2=B.K., last3=Whiteford, first3=W.B., last4=Rodgers, first4=D., year=1984, title=Stratigraphy and structure of the Schoonover sequence, northeastern Nevada—Implications for Paleozoic plate-margin tectonics, journal=Geological Society of America Bulletin, volume=95, pages=1063–1076, bibcode=1984GSAB...95.1063M, doi=10.1130/0016-7606(1984)95<1063:SASOTS>2.0.CO;2, issue=9 {{cite book, last1=Miller, first1=E.L., last2=Miller, first2=M.M., last3=Stevens, first3=C.H., last4=Wfirst4=J.E., last5=Madrid, first5=Raul, year=1992, chapter=Late Paleozoic paleogeographic and tectonic evolution of the western U.S. Cordillera, editor1-last=Burchfiel, editor1-first=B.C., editor2-last=Lipman, editor2-first=P.W., editor3-last=Zoback, editor3-first=M.L., title=The Cordilaeran orogen: Conterminous U.S., publisher=Geological Society of America, series=The Geology of North America, volume=G-3pages=57-106, location=Boulder, Colorado {{cite journal, last=Moores , first=E.M. , year=1970 , title=Ultramafics and orogeny, with models of the US Cordillera and the Tethys , journal=Nature , volume=228 , pages=837–842 , bibcode=1970Natur.228..837M , doi=10.1038/228837a0 , pmid=16058720 , issue=5274 , s2cid=4243830 , url=http://www.ruf.rice.edu/~ctlee/cali/MooresOphioliteCordilleraNature.pdf , url-status=bot: unknown , archiveurl=https://web.archive.org/web/20140308215434/http://www.ruf.rice.edu/~ctlee/cali/MooresOphioliteCordilleraNature.pdf , archivedate=2014-03-08 {{Cite journal, last=Nolan, year=1928, title=A late Paleozoic positive area in Nevada, journal=American Journal of Science, series= 5th, volume=16, pages=153–161, first=T.B, doi=10.2475/ajs.s5-16.92.153, issue=92, bibcode=1928AmJS...16..153N {{cite book, last1=Neuendorf, first1=K.K.E., last2=Mehl, first2=J.P. 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