Sequence Stratigraphic Framework of the Devonian Guilmette Formation, Pahranagat Range, Southeast Nevada

Abstract

The Middle and Late (Givetian through Frasnian) Devonian Guilmette Formation is a proven hydrocarbon reservoir at Grant Canyon Field, Railroad Valley, Nevada, and consists of limestones and dolomites with interbedded sandstones deposited on a broad, stable, shallow platform. The Guilmette was described and interpreted in the Pahranagat Range in Lincoln County, southeastern Nevada, approximately 64 mi southeast of Grant Canyon. The Guilmette Formation has been informally divided into three members based on lithology and depositional environment and separated by sharp contacts. The lower member consists of interbedded carbonate mudstones and wackestones deposited as subtidal to supratidal shallowing-upward cycles. This member appears to represent a relative sea level highstand. The upper member consists of interbedded carbonate mudstones, wackestone, and quartz sandstones deposited as peritidal shallowing-upward cycles. This member was deposited after a relative sea level fall. Thicknesses of each member are laterally consistent within fault blocks but are variable across faults. Interpretation of these cycles in a sequence stratigraphic framework will provide a relative sea level curve for the Middle to Upper Devonian in this area and will permit delineation of potential hydrocarbon reservoirs in the Guilmette basin wide. Preliminary analysis indicates the middle member is the best potential reservoir, whilemore » the sandstones of the upper member provide additional potential reservoirs. Within this framework, analogs to Railroad Valley may be found.« less