The Cerro Gordo Peak quadrangle encompasses part of the southern Inyo Mountains about 25 km east of Lone Pine, California. This area is of interest for its locally intense and historically important mineralization and its exposures of rocks and structural features that are important for reconstructing the geologic history and tectonic evolution of east-central California. The geologic map presented here depicts our current understanding of the complex stratigraphy and structure of this area.
The Cerro Gordo Peak quadrangle is underlain in large part by sedimentary rocks of Ordovician to Triassic age. These strata accumulated on the western continental margin of North America. Ordovician to Early Mississippian strata in the quadrangle are mostly shallow-water marine carbonate rocks that record sedimentation on the continental shelf. By contrast, the overlying Late Mississippian to Triassic strata represent a variety of deep-water marine, shallow-water marine, and nonmarine depositional settings that reflect episodic tectonism along the continental margin. Sedimentation in the quadrangle was accompanied by Early Permian contractional deformation, Late Permian extensional deformation, and a second episode of contractional deformation in latest Permian time. These deformational events are represented by faults, folds, and unconformities exposed in the quadrangle and other nearby areas.
The Jurassic was marked by the spread of volcanic and volcanogenic strata derived from the southwest. This volcanism marked one growth phase of the Sierran magmatic arc, the core of which lay west of the quadrangle. Intrusive outliers of the arc (dikes, sills, and plutons) sporadically invaded the southern Inyo Mountains region during the Jurassic and Cretaceous. Contractional deformation of the East Sierran Thrust System produced northwest-trending thrust faults, folds with accompanying cleavage, general ductile flattening, and conjugate strike-slip faults in the quadrangle primarily during the Late Jurassic.
The Inyo Mountains and the adjacent bounding valleys are the result of late Cenozoic extensional faulting. In the Cerro Gordo Peak quadrangle, early phases of uplift of the Inyo Mountains are marked by middle to late Miocene fanglomerates on both sides of the range. The fanglomerate on the east side of the range overlaps a major zone of normal faulting (Eastern Inyo Fault Zone). More recent deformation is indicated by normal faults that cut the fanglomerates. Northwest-directed extensional tectonism continues in the region today.
File Type and Description
|Text-only readme file that explains how to use the digital database
|geologic map database files and associated files
|Federal Geographic Data Committee (FGDC) compliant metadata file derived from the digital database
FILES for VIEWING and PLOTTING
|A Portable Document Format (PDF) file for viewing and plotting the geologic map at full scale. The plot is approximately 36 x 42 inches in size.
|A 17-page Portable Document Format (PDF) file for viewing and printing a pamphlet that accompanies the map. The pamphlet contains a geologic interpretation and the description of map units.
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