Stratigraphy Of The Devonian Guilmette Formation Pahranagat Range Lincoln County Nevada

Author : F. Michael DeDen
Publisher :
ISBN 13 :
Total Pages : 286 pages
Book Rating : 4.:/5 (19 download)

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Download or read book Stratigraphy, Depositional Environments, and Diagenesis of the Devonian Simonson and Guilmette Formations in the White Pine, Egan, and Schell Creek Ranges, White Pine County, Nevada written by F. Michael DeDen and published by . This book was released on 1987 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Devonian Simonson and Guilmette Formations provide examples of Cordilleran miogeosynclinal inner and middle shelf carbonate deposition that act in response to changes in eustasy, sedimentation, and tectonics. The Simonson Dolomite consists of four members that collectively record three distinct transgressive-regressive cycles. The Coarse Crystalline dolomudstone lithofacies represents restricted upper intertidal to supratidal sedimentation deposited on a distally steepened carbonate ramp. Evolution of the Cordilleran shelf occurred concurrent with deposition of the Lower Alternating cryptalgal dolomudstone lithofacies. A depositional rimmed margin developed recording lagoonal deposition, in the form of upward-shallowing sequences, across the entire Middle Devonian shelf. A continued relative sea-level rise is represented by the lower intertidal to subtidal stromatoporoidal biostromal bank buildups of the Simonson Brown Cliff Member. A relative sea-level fall is recorded by the intertidal to supratidal Upper Alternating dolomud-wackestone lithofacies. Four lithofacies and nine subfacies are differentiated for the Guilmette Formation, representing a broad spectrum of shallow subtidal to intertidal environments. Thick buildups of primarily wackestone and packstone lithofacies accumulated in response to a continued relative sea-level rise. The extensive lateral growth of stromatoporoidal biostromal bank buildups formed under open-marine conditions while more restricted lagoonal environments dominated the inner shelf. Acting in response to initial Antler orogenic foreland effects and in concert with a continuing rise of sea-level, the Guilmette lithotope was eliminated in the Late Devonian along with the Cordilleran depositional rimmed margin. Diagenetic fabric relationships observed in the Simonson and Guilmette reveal a complex history beginning with the early-submarine cementation of aragonite and/or high-Mg calcite. Neomorphic processes followed and resulted in the stabilization to low-Mg calcite. Diagenesis continued in the deep subsurface and included silica cementation and replacement events that both predated and act concurrently with pressure-solution stylolitization and dolomitization. Late diagenetic silicification postdated both burial dolomitization and secondary porosity evolution. Calcite pore and fracture-filling cementation postdated all diagenetic events. Diagenetic textures reflect deep-burial processes rather than the original depositional environment. Reservoir qualities have been enhanced by late-diagenetic dolomitization producing secondary intercrystalline porosity within dolomitic Guilmette horizons and especially in the Simonson Coarse Crystalline Member.