Geology of Paleozoic rocks in eastern Sierra Nevada roof pendants, California
Calvin H. Stevens, David C. Greene, 2000. "Geology of Paleozoic rocks in eastern Sierra Nevada roof pendants, California", Great Basin and Sierra Nevada, David R. Lageson, Stephen G. Peters, Mary M. Lahren
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Rocks in the major roof pendants of the eastern Sierra Nevada have been mapped in various degrees of detail to better understand their stratigraphy, internal structure, and geologic history, and their relationships to other rock assemblages in the region. Ten formations ranging in age from Middle(?) Cambrian to Middle(?) Permian are recognized in these pendants, which along with other minor pendants, constitute a tectonostratigraphic unit called the Morrison block.
Rocks of the Morrison block were first deformed by north-northwest-trending thrust faults and footwall syn-clines involving strata as young as Early or Middle Permian. We designate this event, which correlates with a similar pre-middle Early Triassic event recognized in rocks near Tinemaha Reservoir, the Morrison orogeny. Structures produced during this orogeny include a probable cryptic thrust fault separating rocks assigned to the Morrison block from those in the Big Pine Creek pendant, which may belong to the White-Inyo block, and the Nevahbe thrust, which separates lower from upper Paleozoic rocks in the eastern part of the Mount Morrison pendant and may separate the Pine Creek and Bishop Creek pendants. In the Mount Morrison pendant structures produced during the Morrison orogeny apparently were later refolded twice prior to sinistral displacement on the Laurel-Convict fault, which cross-cuts older structures and is intruded by a pre-latest Late Triassic dike.
Other thrust faults in the eastern Sierra Nevada include the Golconda thrust of early Middle Triassic age and the Lundy Canyon thrust of Late Triassic age. The Golconda thrust system apparently overprints the Roberts Mountains thrust and separates rocks of the Morrison block from those of the Golconda and Roberts Mountains allochthons in the Saddlebag Lake pendant, and perhaps from those of the Roberts Mountains allochthon in the Northern Ritter Range and Log Cabin Mine pendants.
After thrust-faulting, but prior to intrusion of the Late Triassic Wheeler Crest Granodiorite, dextral movement on the Tinemaha fault displaced Paleozoic facies and structural belts in the Sierra Nevada northward, producing most of the present complicated paleogeographic patterns apparent in the region. Other less important structures, such as the Laurel-Convict fault, have further complicated the geology of the Morrison block.
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Great Basin and Sierra Nevada, the second volume of the Geological Society of America Field Guide Series, focuses on the dynamic and spectacular geology of this region, providing the inspiring backdrop for the 2000 GSA Annual Meeting in Reno. This volume gives complete coverage of field trips held in conjunction with that meeting, and contains 20 chapters organized into three sections. The first section consists of 16 chapters arranged in geochronological order, beginning with the active tectonics of Lake Tahoe and the historical surface faulting and paleoseismicity of the central Nevada seismic belt, and ending with the Neoproterozoic glacial record of Death Valley. In between are chapters dealing with Basin and Range extension, Eocene magmatism, Mesozoic plutonism in the Sierra Nevada, Paleozoic subduction, and Ordovician stratigraphy, to name a few. The second section covers the geology of the Nevada Test Site and the nuclear-waste repository at Yucca Mountain. The last section is an invited field guide from the 1999 GSA Cordilleran Section meeting that covers the wines and geology of Napa Valley, California. Overall, Great Basin and Sierra Nevada is a comprehensive compilation of new and exciting research on this amazingly diverse region, with well-crafted guides to field localities of special interest. Full-color plates in some chapters make this guide an especially appealing and useful volume.