韧性剪切变形对岩石地球化学行为的制约——以北阿尔金巴什考供韧性剪切带为例

韧性剪切变形对岩石地球化学行为的制约一直是地质学家们探讨的课题。本文以构成北阿尔金红柳沟——拉配泉俯冲碰撞杂岩带与北阿尔金地块边界的巴什考供斜向逆冲型韧性剪切带为例，通过对韧性剪切带内花岗岩变形前后不同变形强度构造岩的地球化学组成进行对比，确定等比线斜率，探讨韧性变形对岩石体积和成分变异的影响。计算结果表明，在糜棱岩化过程中，糜棱岩化花岗岩体积亏损21％，花岗质糜棱岩体积亏损31％。质量平衡计算结果和等比线图表明，韧；陛剪切作用导致SiO2，流失量最大，A12O3、K2O及Ba、Rb、Sr等都有不同程度的丢失，显示出较强的活动性，MnO、P2O5、Sc位于等比线上或附近，表现出相对的稳定性。岩石中活动组分的变异是流体渗滤作用引起的，不活动组分的变异是体．积亏损造成的。

Constraints of ductile shear deformation on rock geochemical behavior-an example from the Bashikaogong ductile shear zone in the northern Altyn Tagh

The constraints of ductile shear deformation on rock geochemical behaviors have long been a subject discussed by geologists. Take for example the Bashikaogong oblique thrust ductile shear zone that forms the boundary between the northern Altyn Tagh-Hongliugou-Lapeiquan subduction-collision complex zone and the northern Altyn Tagh block, the authors estimate the influences of ductile shear deformation on the rock volume loss and compositional variation by comparing the geochemical compositions of tectonite of different deformation intensities before and after deformation of granodiorite in the Bashikaogong ductile shear zone and determine the isocon line slopes. The calculation shows that the volume losses of mylonitized granodiorite and granodioritic mylonite during mylonitization are 21% and 31% respectively. The mass balance analysis and isocon diagram indicate that the loss of SiO2 is largest, while Al2O3, K2O and Ba, Rb and Sr lose to different extent, showing that they are mobile components in the rock. MnO, P2O5 and Sc, which are located at or near the isocon line, are immobile components. The variation of mobile components in the rock was caused by fluid infiltration, while the variation of immobile components resulted from the volume loss during mylonitization.