Longevity of fracture in crystalline rocks by using Rb-Sr dating method

本文重点研究了花岗质岩石裂缝的形成过程和形成年龄。结果表明：不同类型的岩体具有相同的压裂和裂缝充填阶段，主要表现为：岩体侵入后的韧性-脆性转变过程中温度降低导致的脆性张性压裂（第一期）；相对快速的隆升伴随着热液水循环，产生未破碎的层状矿物充填物（第二阶段）；隆升后暴露后的低温大气水循环期（第三阶段）。碳酸盐矿物裂缝充填物的共生特征及其碳同位素组成（^<14C>,δ^<13> C）表明，在岩体快速隆升过程中存在明显的碳酸盐矿物沉淀期。在每个时期形成的碳酸盐矿物都含有来自不同来源的碳。这里确定的充填物的演化使我们能够在造山场的岩体中发展出一种特殊的压裂模型和流体传导系统的持久性。

In this research, formation process and the age of formation of fracture in granitic rocks has been focused. The result shows that different plutons have identical episodes of fracturing and fracture filling, consisting of : brittle tensile fracturing, due to decreasing temperature through the ductile-brittle transition after plutonic intrusion(Stage I); relatively rapid uplifting accompanied by hydrothermal water circulation which produced un-crushed layered mineral fillings(Stage II); and a period of low-temperature meteoric water circulation following exposure after uplift(Stage III). The parageneses of carbonate mineral fracture fillings and their carbon isotopic compositions(^<14C>,δ^<13> C) show that there were distinct episodes of carbonate mineral precipitation during the rapid uplifting of a pluton. The carbonate minerals that formed during each episode incorporated carbon from a distinct source. The evolution of fillings identified here enable development of a specific model of fracturing and persistence of fluid conducting systems in the plutons of the orogenic field.