Compositional variation and volume loss of a shear zone - Hetai shear zone as a case history

摘要

In a shear zone, being a defect within the earth crust, there must be a coupling of thermal, mechanical, chemical and fluidal processes. The chemical disequilibrium and component migration caused by strain localization and mechanical instability induce the readjustment of chemical compositions within a shear zone. There are different ways of interpretation for chemical element enrichment and depletion within a shear zone. However, it is commonly accepted that the enrichment of some elements, especially immobile high field-strength elements (such as Ti, P, Zr, Y and V), is probably related to the volume loss in shear zones. Besides the strain, fluid flow is one of the most important factors contributive to the volume loss of shear zones. The presentnote is aimed at the characteristics of chemical composition variation and their relationship with volume loss and fluid flow in the light of the Hetai shear zone, Guangdong Province.