Vertical Chemical Variation of the Mesozoic Synuplift Plutonic Rocks in Dabieshan Orogen, Central China

摘要

The Dabieshan orogen had undergone strong differential uplift-exhumation during the Mesozoic The Beihuaiyang massif located on the north side of the Tongbai-Tongcheng Fault Zone (TFZ) has been of an exhumation magnitutc of less than 5 km since 170 Ma. On the south side of the TFZ, the rooks of the East Dabie massif now at the surface were buried to a depth of approximately 18 km at 227 Ma, and plutonio emplacement of-220-120 Ma was accompanied by uplift-exhumation of 8-10 km. There is a series of Mesozoic plutons exposed in East Dabie massif, which were unplaced synchronously with the rock uplift-exhumation of Dabieshan Mountains. This paper addresses the vertical chemical variation of the Mesozoic synuplift plutons at Dabieshan orogen. It is suggested that Fe2O3, TiCh, P2O5, MgO, CaO, AI2O3 and ClPW-nonnative An are positively correlated with plutonic emplacement pressure; S1O2, K2O, Rb, Ba, Zr, Hf and CIPW-normative Or are negatively correlated with the pressure; and the vertical chemical variation should be mainly controlled by buoyancy and upward migration of pore-fluid material.