Geology Of The Willow Creek Area Elko County Nevada

Author : John H. Whitaker
Publisher :
ISBN 13 :
Total Pages : 232 pages
Book Rating : 4.:/5 (13 download)

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Download or read book Geology of the Willow Creek Area, Elko County, Nevada written by John H. Whitaker and published by . This book was released on 1985 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this study was to test two hypotheses. The first hypothesis interprets allochthonous rocks in the Willow Creek area of the Pinyon Range as lying on flat, superficial thrusts that truncate the underlying folded Mississippian rocks of the Antler flysch sequence. The second hypothesis interprets the allochthonous rocks as being folded within the Mississippian sequence as if they had arrived as part of the Antler allochthon after flysch sedimentation had begun and were overlapped as sedimentation continued. Evidence presented here supports the second hypothesis. During Early and Middle Devonian time, deposition in the central Pinyon Range occurred in a miogeoclinal shallow-shelf environment characterized by carbonates of the Nevada Group. Onset of the Antler orogeny in Late Devonian time was marked by uplift and erosion or nondeposition in the study area. A west-dipping subduction zone formed to the west in oceanic crust, developing an accretionary wedge which became the Roberts Mountains allochthon. The allochthon was obducted onto the continent as incipient subduction of continental crust occurred. Downbending of the edge of the continent led to the formation of a foreland trough at the leading edge of the allochthon. Telescoping within the allochthon caused it to rise and shed siliciclastic sediments into the trough forming the submarine fan deposits of the Dale Canyon Formation. The allochthon was then emplaced over the Dale Canyon Formation and was subsequently overlapped by deltaic sediments of the Diamond Peak Formation. The Roberts Mountains allochthon in the Willow Creek area consists of the Devonian Woodruff Formation forming its base, the Ordovician Vinini Formation at the top, with a small slice of the Siluro-Devonian Roberts Mountains Formation lying in between. Emplacement of the allochthon is dated as during or before typicus Zone time of the early Osagean on the basis of conodont collections from the overlapping Diamond Peak Formation.