Abstract

The Laurel-Convict fault is a prominent, northwest-striking, high-angle fault exposed in Paleozoic rocks of the Mount Morrison pendant in the eastern Sierra Nevada of California. The fault zone averages 25–50 m in width and consists of narrow, anastomosing domains of ductile deformation separating lenses of Paleozoic metasedimentary rock. The fault, which cuts structures in middle Permian metasedimentary rocks, is intruded by a relatively undeformed quartz porphyry felsite dike that has yielded a U-Pb zircon upper intercept age of 225 ± 16 Ma. Displacement on the Laurel-Convict fault is therefore constrained to the interval between middle Permian and Late Triassic. Displacement criteria, including curvature and offset of bedding in the fault zone, rare mesoscopic ductile shear indicators, and restoration of offset lower Paleozoic stratigraphy and structure across splay faults, all indicate a moderate amount of apparent left-lateral strike-slip displacement. Our data do not support previous interpretations of the Laurel-Convict fault as a thrust-faulted terrane boundary or a major right-lateral shear zone. The Laurel-Convict fault is not, therefore, an exposed segment of Intrabatholithic Break 3 (IBB3), thus proposed Cretaceous right-lateral displacement of the Sri = 0.706 isopleth on IBB3 must be accommodated either east of the Mount Morrison pendant in the Owens Valley or west of the pendant in the eastern Sierra Nevada.

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