褶皱形成过程中常量元素的地球化学行为及岩石体变的估算问题

CEOCHEMICAL BEHAVIOR OF MAJOR ELEMENTS AND ESTIMATION OF VOLUME CHAMGES DURING FOLD FORMATION

本文简要地论述了常量元素在弯曲滑动褶皱作用、弯曲流动褶皱作用、被动褶皱作用以及轴面折劈理和轴面流劈理形成过程中的地球化学行为,并将其与中—大型褶皱形成过程中常量元素的地球化学行为进行对比.笔者认为,褶皱形成过程中常量元素的活动性序列与岩石的矿物组成及结构构造、变形的温度、压力环境、交形机制以及孔隙溶液的物理化学性质均密切相关,任何试图建立一个普遍适用的元素活动性序列的想法都是不现实的.最后,本文论证了岩石组分含量初始分析值进行体积校正的必要性,并介绍了估算褶皱形成过程中岩石体积变化的方法.

This paper synthetically discusses geochemical behavior of major elements during flexural-slip folding, flexural-flow folding, shear folding, and the formation of axial-plane crenulation cleavage and axial-plane slaty cleavage. Then the paper compares them with those during the formation of medium-to large-scale folds. During formation of folds,the mobilities of major elements depend upon the mineral constitution and rock texture, p-T environment of deformation, deformation mechanism and the physical-chemical properties of pore solution. Therefore, it is impossible to establish a single mobility sequence of major elements and apply it to all types of folding and rock. Finally, the paper proves the necessity for volume-change correction for initial analytical results of major-element content , and introduces a method to estimate rock volume changes during folding.