Evaluating the Mojave-Snow Lake fault hypothesis and origins of central Sierran metasedimentary pendant strata using detrital zircon provenance analyses

Abstract

Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) detrital zircon age data and detailed mapping of metasedimentary and metavolcanic pendants in the central Sierra Nevada are used to examine the age and origin of the metasediments, and to search for evidence of the location and history of the Cretaceous Mojave-Snow Lake fault. Quartzites from the Snow Lake, Benson Lake, May Lake, and Quartzite Peak pendants yield age spectra that best match Neoproterozoic to Ordovician passive-margin strata, thus supporting the presence of displaced passive-margin strata now preserved in Sierran pendants. Sediments at Cinko Lake, Strawberry Mine, and NE of Snow Lake are interpreted to be Early Jurassic to Early Cretaceous and marine, and probably not equivalents of the Fairview Valley Formation at Black Mountain as previously interpreted. Without this correlation, the suggested 400 km of displacement along the Mojave-Snow Lake fault is unconstrained, the exact location of origin for these passive-margin and Jurassic marine metasediments is uncertain, and the nature of the contact between these two sediment packages, which has been suggested to be an angular unconformity, is speculative and deserving of a more detailed evaluation. The timing of displacement along the inferred dextral Snow Lake fault is constrained to be between ca. 145 Ma, the maximum depositional age of Jurassic strata at Cinko Lake, and 102 Ma and 103-108 Ma, the age of the oldest intruding pluton and the youngest volcanic rocks juxtaposed along the stratigraphic break with adjacent eugeoclinal rocks. © 2010 Geological Society of America.