9706521 Sisson The uplift and exhumation of high-pressure metamorphic rocks related to subduction is a classic, unsolved geologic problem. High P/low T assemblages are generally thought to have formed a t great depth in subduction zones, but brought to the surface by a variety of possible mechanisms, resulting in two "types"- one characterized by retrograde, approximately isothermal decompression, and the other by a decompression path parallel to their prograde P/T path. In northern Venezuela there are two occurrences of High P/low T metamorphic belts of the same age and thought to be associated with the same subduction zone. However one is of the "Franciscan-type" and the other of the "Alpine-Type". This project will attempt to exploit this circumstance and isolate the mechanisms of uplift and ascent leading to the different types, and will involve extensive structural and petrologic study of each occurrence. Results have the potential for shedding considerable light on the uplift and exposure of rocks metamorphosed deep in subduction zones.
