Correlation of Permian and Triassic deformations in the western Great Basin and eastern Sierra Nevada: Evidence from the northern Inyo Mountains near Tinemaha Reservoir, east-central California
Geologic relationships exposed near Tinemaha Reservoir southeast of Big Pine, east-central California, provide key chronological and structural constraints for linking Permian and Triassic deformational events recognized in the White and Inyo Mountains in the western Great Basin with those in the eastern Sierra Nevada, particularly the Mount Morrison and Saddlebag Lake pendants. Permian to earliest Triassic deformation in the Tinemaha Reservoir area produced a large north- to northwest-trending, east-vergent, originally recumbent syncline (Mule Spring syncline) cut by an overriding thrust (Strange Hill thrust). We correlate this deformation with a middle Permian to earliest Triassic contractional deformation recognized in the southern Inyo Mountains, and with a major episode of folding and thrust faulting in the eastern Sierra Nevada. After a period of tectonic quiescence and marine sedimentation in the Early Triassic, rocks in the Tinemaha Reservoir area were refolded twice, producing distinctive sets of steeply plunging folds. Similar structures in the Mount Morrison pendant that formed prior to intrusion of a 225 ± 16 Ma dike along the Laurel-Convict fault are correlated with those in the Tinemaha Reservoir area. The timing of these folding events may be similar to that of displacement on the Golconda and/or Lundy Canyon thrusts in the Saddlebag Lake pendant. Close structural and stratigraphic ties suggest that rocks in the northeastern part of the Mount Morrison pendant and Tinemaha Reservoir area, now separated by ∼65 km of dextral displacement along the cryptic Tinemaha fault, originally lay adjacent to one another. This offset postdates Triassic folding and is inferred to predate emplacement of the latest Triassic Wheeler Crest Granodiorite, which crops out across the projected fault trace.