EXHUMATION OF THE DABIE-SHAN ULTRA HIGH-PRESSURE ROCKS AND ACCUMULATION OF THE SONGPAN-GANZI FLYSCH SEQUENCE, CENTRAL CHINA

The presence of coesite- and diamond-bearing ultra-high-pressure (UHP) metamorphic rocks in the Dabie and Sulu regions, central China, sugge sts that a > 100-km-thick crustal section (4 x 10(6) km3 in volume) ha s been denudded. This volume is comparable to that represented by the 10-15-km-thick Middle to Upper Triassic flysch rocks in the Songpan-Ga nzi region. Regional geology and radiometric dates are compatible with an interpretation that the majority of these sedimentary rocks were d erived from denudation of the orogenic belt between North and South Ch ina blocks following their latest Paleozoic to Triassic collision. Thi s correlation implies a high denudation rate of approximately 4 mm/yr that may have been in part promoted by tropical precipitation and extr eme topographic relief for as long as 25 m.y.