Collaborative Research: Subduction and Exhumation of Ultrahigh-Pressure Rocks: Field and Drilling Petrotectonic Studies in Eastern China

Carnegie Institution Of Washington, Washington DC

Investigators

Abstract

0507331 Rumble This project will continue geochemical and chronological analyses of drill core and outcrop samples obtained in the course of studying an ultrahigh-pressure (UHP) terrane in China. The Chinese Continental Drilling Project (CCSD), in the Donghai area of the Sulu terrane, provides a unique opportunity to study this important belt in three dimensions. The drilling is just now winding up with the completion of several shallow holes and one 5-km deep borehole. Field studies of the Dabie-Sulu belt and the initial studies of borehole samples have provided many new insights into the processes involved in the subduction and exhumation of continental material and into the processes of high P - low T metamorphism; presently a "hot topic" in earth sciences. Specifically, the Dabie-Sulu suture zone appears to be one of the best places in the world to address the conditions under which crustal rocks are taken to depths of more than 100 km and then returned to the surface, as well as the question of how mantle rocks from depths of >200 km are transported to shallow depths and incorporated into subducted continental slabs or mountain belts. The project is the continuation of the PI's long term collaborations with Chinese colleagues who have played a major role in the drilling. The major US role involves detailed mineralogical studies of drill core samples.