Tectonics of the Dabieshan (eastern China) and possible exhumation mechanism of ultra high-pressure rocks

The Dabieshan is divided into three tectonic domains. The Southern Dabiesha n is a stack of allochtons, from top to bottom: (i) unmetamorphosed Cambria n-Early Triassic series unconformably covered by Jurassic sandstone; (ii) w eakly metamorphosed Proterozoic slate; (iii) HP rocks mostly retrogressed i nto greenschist facies; (iv) UHP allochton; (v) UHP-free gneisses. These un its exhibit a NW-SE lineation and top-to-the-NW shearing reworked by S-verg ing folds. The Central Dabieshan is a migmatitic dome superimposed on UHP m etamorphism and bounded by a detachement fault responsible for the exhumati on of the UHP unit during its retrogression into amphibolite facies. In the Northern Dabieshan, early foliation and N-S trending compressional lineati on are deformed by N-verging folds coeval to the syn-exhumation ductile str uctures of the Central Dabieshan. A geodynamic model involving coeval thrus ting and normal faulting is discussed.