EXPLORING THE GEOCHEMICAL CHARACTER OF VOLCANISM IN THE WHIPPLE MOUNTAINS REGION, CA AND AZ; DID CRUSTAL MELTING PLAY A ROLE IN THE EXTENSIONAL COLLAPSE OF THE COLORADO RIVER EXTENSIONAL CORRIDOR?
Eruption of a 1 km thick section of mafic lava flows and a 1-0.5 km thick section of silicic lavas flows and domes occurred over 1.5 million years. This eruptive period ended with a dramatic extensional event (19 Ma) that resulted in 40-60° of block rotation across the corridor. After this, volcanism was characterized by less frequent, smaller volume, primarily mafic eruptions. The fact that extensional block rotation followed so closely on the heels of the sustained, voluminous eruption of crustal-hybrid lavas suggests that the temporal link is more than just coincidence. We argue that the geochemical data is consistent with the hypothesis that thermal weakening of the crust drove extensional collapse within the LCREC.