title: Footwall refrigeration along a detachment fault: implications for the thermal evolution of core complexes
abstract: Oxygen isotope compositions of epidote and quartz from chloritic breccias that underlie the detachment fault in the metamorphic core complex of the Whipple Mountains yielded quartz-epidote fractionations that range from 4.1 to 6.4 per mil and increase systematically toward the fault. These fractionations give mean temperatures that decrease from approximately 432 degrees C at 50 meters below the fault to approximately 350 degrees C at 12 meters below the fault. This extreme thermal gradient of 82 degrees C over 38 meters (2160 degrees C per kilometer) is best explained by advective heat extraction by means of circulating surface-derived fluids. Models of lithospheric extension consider only conductive cooling resulting from tectonic denudation and thus require revision to include fluid-induced fault-zone refrigeration.
authors.affiliation: Department of Earth Sciences, University of Southern California, Los Angeles, CA 90089-0740, USA.
authors.initials: J
authors.lastname: Morrison
authors.initials: JL
authors.lastname: Anderson