CRUSTAL MELTING IN THE SOUTHERN CORDILLERA: THE PAN-TAK GRANITE OF THE COYOTE MOUNTAINS METAMORPHIC CORE COMPLEX, ARIZONA

The Pan-Tak granite in the Coyote Mountain metamorphic core complex is an early Paleogene peraluminous leucogranite located ~45km southwest of Tucson, Arizona. The Pan-Tak granite is interpreted as the product of crustal melting of Proterozoic metapelitic rocks, which makes it part of a belt of peraluminous, two-mica +/- garnet, leucogranites associated with core complexes that stretches from British Columbia, Canada to Sonora, Mexico. Crystallization ages of anatectic intrusive rocks in the northern Cordillera (e.g., Shuswap complex) correlate well with exhumation ages of their respective core complexes, suggesting decompression melting as a primary mechanism for melt production. However, exhumation/cooling ages and crystallization ages related to anatexis in the Coyote Mountains diverge by ca. 30 Ma. Therefore, other process may be required to explain melting including: crustal thickening, magmatic heating, and fluid-flux. We present new geochronological and geochemical data to help resolve the origin of the Pan Take granite and its relationship to the tectonic history of southern Arizona.