ALONG-STRIKE ANALYSIS OF THE SIERRA NEVADA-PENINSULAR RANGES LATE CRETACEOUS CORDILLERAN BATHOLITH FLARE-UP

New and published data demonstrate the continuity of the Cordilleran mid-Cretaceous (100-85 Ma) Sierra Nevada-Peninsular Ranges batholith flare-up event from northwestern Nevada to the southern tip of Baja California over a strike length of 2500 km. This belt is characterized by a series of large, nested, generally inward-younging intrusive suites with more mafic peripheries relative to more felsic cores. Post-emplacement uplift and erosion has removed supracrustal volcanic/sedimentary cover. Plutons throughout the belt were generated by melting of relatively deep crustal sources based on REE fractionation patterns and elevated Sr/Y ratios, and the consanguinity of intrusion is well-documented by more than 170 widely distributed zircon U/Pb ages. Wallrock varies dramatically along strike from basinal early Mesozoic oceanic arc terranes in the north and south to more fertile continental lithosphere in the southern Sierra Nevada segment, as reflected by along strike variation in Sr-Nd tracer isotopic data. Oxygen isotope data show that contributions of supracrustal source materials to the source region of the magma generation varied greatly along strike. Zircon Hf isotopic compositions of ‘flareup’ granitoids from the Peninsular Ranges yield systematically lower εHf values relative to associated gabbro suggesting that that the granitoids cannot simply represent remelting of gabbroic/mafic underplated crust. Age probability distribution of inherited zircon grains from the Peninsular Ranges segment closely match detrital zircon age distributions from batholith derived forearc sediments as well as Catalina Schist metasedimentary rocks demonstrating crustal recycling of forearc subduction erosion products into source melt regions over short time scales.