Stratigraphic Framework for Late Cambrian-Early Ordovician Carbonate Slope/Toe-of-Slope Sediments, Tybo Canyon, Hot Creek Range, Nevada

Marek, Sandra; Lira, Mario; Pope, Micheal C.

The Late Cambrian-Early Ordovician Hales Limestone is well-exposed in Tybo Canyon of the Hot Creek Range, Nevada. Field work involved measuring multiple full and partial stratigraphic sections of the exposed Hales Limestone to determine vertical changes in lithology throughout the slope/toe-of-slope depositional sediments. A handheld gamma ray scintillometer was used to construct vertical gamma ray logs coincident with the measured sections. The gamma ray logs will be used to help correlate wireline logs from nearby drilled wells to exposed stratigraphy. Gigapan© photomosaics were taken with a 300mm-zoom lens to map out lateral continuity of debris flow beds that were also mapped in the field. These photomosaics with field mapping data also help to discern 3-D geometries of the slope units deposited. Facies consist predominantly of thin-bedded carbonate mudstone or clast-supported or matrix-supported conglomerate. The mudstone comprises the majority of the sediments and likely formed as pelagic rain out on the slope or toe-of-slope. The clast-supported and matrix-supported conglomerates likely are debris flow deposits. Clast-supported debris flows are more prominent in outcrop, and orientation direction, clast size, and clast sorting were identified in the flows. Debris flows with clasts oriented along the bed plane are likely a result of slumping sediments; several locations showed small clast-supported zones within the thin-bedded mud. The matrix-supported debris flows were not as common and did not appear as continuous as the clast-supported debris flows. The majority of the clasts are carbonate mudstone indicating the source of the clasts was the slope environment. Thin sections from rock samples will be analyzed to determine petrographic characteristics that make this deep water depositional environment a potential fluid reservoir. The results of this project will provide a better understanding of deep water carbonate depositional environments, their potential reservoir continuity and extent, and the reservoir quality of their sediments.

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013