THE LAUREL-CONVICT FAULT, EASTERN SIERRA-NEVADA, CALIFORNIA - A PERMO-TRIASSIC LEFT-LATERAL FAULT, NOT A CRETACEOUS INTRABATHOLITHIC BREAK

The Laurel-Convict fault is a prominent, northwest-striking, high-angl e fault exposed in Paleozoic rocks of the Mount Morrison pendant in th e eastern Sierra Nevada of California. The fault zone averages 25-50 m in width and consists of narrow, anastomosing domains of ductile defo rmation separating lenses of Paleozoic metasedimentary rock. The fault , which cuts structures in middle Permian metasedimentary rocks, is in truded by a relatively undeformed quartz porphyry felsite dike that ha s yielded a U-Pb zircon upper intercept age of 225 +/- 16 Ma, Displace ment on the Laurel-Convict fault is therefore constrained to the inter val between middle Permian and Late Triassic. Displacement criteria, i ncluding curvature and offset of bedding in the fault zone, rare mesos copic ductile shear indicators, and restoration of offset lower Paleoz oic stratigraphy and structure across splay faults, all indicate a mod erate amount of apparent left-lateral strike-slip displacement. Our da ta do not support previous interpretations of the Laurel-Convict fault as a thrust-faulted terrane boundary or a major right-lateral shear z one. The Laurel-Convict fault is not, therefore, an exposed segment of Intrabatholithic Break 3 (IBB3). Proposed Cretaceous right-lateral di splacement of the Sr-i = 0.706 isopleth on IBB3 must be accommodated e ither east of the Mount Morrison pendant in the Owens Valley or west o f the pendant in the eastern Sierra Nevada.