DISPERSAL OF SOUTHERN SIERRA NEVADA BATHOLITH (SNB) CRUSTAL FRAGMENTS ACROSS AND ALONG THE TRACE OF THE SAN ANDREAS FAULT (SAF)-WHAT CONSTITUTES THE CENTRAL SALINIA BASEMENT

Analysis of the main Salinia basement indicates that it consists of crustal fragments that may be correlated with various crustal levels of the southern SNB, and its disrupted continuation into the Mojave batholith. The clearest correlations are between the San Emigdio-Tehachapi and Gabilan Ranges. Mid-Cretaceous mid-to upper crustal eastern zone batholithic and metamorphic pendant rocks of the main Gabilan massif correlate to the Pastoria plate, which sits above lower crustal western zone Early Cretaceous SNB rocks of the San Emigdio-Tehachapi ranges along a folded regional detachment fault of Late Cretaceous age. Through much of the San Emigdio range the detachment completely cuts out the deep SNB plate and places Pastoria plate directly onto underplated trench sediments of the Rand schist. The same relationship exists at the southern end of the Gabilan’s where correlative mid-crustal granitoids sit tectonically on correlative schists of Sierra de Salinas. Palinspastic restoration of the Pastoria-Gabilan plate based on regional primary batholithic zonation patterns, and complementary crustal levels, places the allochthon above the SE SNB northeast of Tehachapi Valley. Logan Quarry crystalline rocks, and several other small slivers along the inner edge of Salinia correlate to basement inlier rocks nonconformably beneath Maastrichtian(?) to early Paleogene marine strata of the westernmost San Emigdio range. These rocks constitute a fragment of the Sierra Foothills metamorphic belt that restores to a detachment surface that forms the nonconformity at the base of the eastern Maricopa basin Tertiary section. Utilizing primary batholithic zonation patterns, crustal levels and transport data on the Salinas shear zone that bounds underplated trench sediments, the Santa Lucia-Sierra de Salinas massif restores to western Mojave lower crust, beneath the site of the west Antelope basin. Dispersal of the Salinia crustal fragments first involved SW-directed large magnitude extension of the southernmost SNB-western Mojave batholith above a shallow flat subduction segment as underplated trench sediments were educted from the Late Cretaceous subduction zone in a regional return flow channel. The trenchward displaced batholithic fragments were rendered liable for further dispersal along the SAF system.