Exhumation of Two Contrasting High-Pressure Metamorphic Belts in Venezuela: Implications for Caribbean Tectonics

与俯冲有关的高压变质岩的隆升和掘出是一个经典的、尚未解决的地质问题。高P/低T组合通常被认为在俯冲带中形成很深的深度，但通过各种可能的机制带到地表，形成两种“类型”，一种以逆行、近似等温减压为特征，另一种以平行于其前进P/T路径的减压路径为特征。在委内瑞拉北部有两个相同年代的高P/低T变质带，被认为与同一俯冲带有关。然而，一个是“方济会型”，另一个是“阿尔卑斯型”。该项目将尝试利用这种情况，隔离导致不同类型的隆起和上升机制，并将对每个产层进行广泛的构造和岩石学研究。结果有可能对俯冲带深部变质岩石的隆升和暴露提供相当大的启示。

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.