秦岭造山带碰撞及碰撞后侵入岩地球化学特征

以洛南-栾川断裂、商丹板块缝合带和勉略板块缝合带为界，从北到南将研究区依次划分为：华北板块南缘构造岩浆区（简称SC岩区）、北秦岭构造岩浆区（简称NQ岩区）、南秦岭构造岩浆区（简称SQ岩区）、西秦岭构造岩浆区（简称WQ岩区）。依据各构造岩浆区内碰撞及碰撞后侵入岩的化学成分及出露面积，估算了各构造岩浆区及整个研究区碰撞及碰撞后侵入岩的平均化学成分。研究结果表明，各构造岩浆区碰撞及碰撞后侵入岩的平均化学成分相当于花岗岩；由南向北碰撞及碰撞后侵入岩微量元素含量的变化规律类似于区域地壳元素丰度的变化规律．从早到晚．从西向东碰撞及碰撞后侵入岩岩浆朝着富硅、富碱方向演化，逐渐显示出A型花岗岩的特点。

CHEMICAL CHARACTERISTICS OF SYN-AND POST-COLLISIONAL PLUTONS IN QINLING OROGEN

The Qinling orogenic belt is comped of four tectonic magma provinces. They are the south tec-tonic magma province of the North China plate (SC province), the north Qinling tectonic mngmaprovince (NQ province), the south Qinling tectonic magma province (SQ province), and the westQinling tectonic magma province (WQ province). Between the SC province and the NQ province isthe Luonan-Luanchuan fault. Between the NQ and the SQ provinces there has developed the Sang-Dansuture zone. The Mian-Lue suture zone constitutes the southern boundary of the SQ province. Basedon the outcropped areas and the chemical compositions of the syn- and post-collisional plutons, the av-erage chemical compositions of the syn- and post collisional plutons in these four tectonic magmaprovinces are estimated. The results indicate that the average chemical compositions of the WQ, SQ,NQ and SC provinces are comparable with those of granites. From the SQ province to the SCprovince, variations in trace element abundances for these provinces are similar to those of the regionalcrust. From the SQ province to the WQ province, the magmas responsible for the syn-and post-colli-sional plutons are rich in silica and alkali, showing the characteristics of the A-type granites.