Evidence for polybaric fractional crystallization in a continental arc: Hidden Lakes mafic complex, Sierra Nevada batholith, California

Although the voluminous granitoids that constitute upper crust of Sierra Nevada batholith (California) have been investigated in detail, comparatively few studies focus on origin mafic bodies at similar crustal levels. Here, we present field and petrographic observations, geochronology, geochemistry Hidden Lakes complex central-eastern batholith. Our results show comprises norites, gabbros, monzondiorites, monzonites record fractional crystallization a hydrous (~ 3 wt% H2O), non-primitive basalt within (0.3 GPa) c. 95–96 Ma. To quantitatively model generation observed lithologies, construct two-stage polybaric based cumulate melt-like bulk-rock compositions. In first step, fractionation primitive, mantle-derived > 30 km depth, generating dominantly pyroxenite cumulates. The evolution derivative melt (67% mass remaining) is then modeled to fractionate 12 depth produce lithologies complex. Extension this higher-silica compositions (> 65 SiO2) replicates granodiorite batholith, suggesting could be an important process for arc granitoid melts. differentiation continental arcs debated, as observations indicate abundant lower while experimental data suggest high-pressure basalts cannot non-peraluminous batholiths. supports one potential mechanism resolve inconsistency.