弹性地质温压计的合理应用:以石榴子石中石英包裹体压力计为例被引量：2

Geological application of elastic geo-thermobarometry:Example of quartz-in-garnet(QuiG)barometry

下载PDF

导出

摘要压力和温度是利用岩石学研究地质过程的核心参数。传统的计算岩石温压条件的方法常要求矿物间达到化学平衡,如相平衡和矿物化学温压计。但是,自然界一些岩石中的矿物组合不一定能达到平衡。基于矿物弹性开发的地质压力计则不受这一条件的影响,它的原理是利用矿物包裹体中保存的残余应力来恢复其被捕获时的压力条件。这种方法能简单快速地获取数据,以实现对温度压力的限定。目前,最常使用石榴子石中的石英包裹体及其弹性地质压力计来确定包裹体的压力。弹性地质压力计的应用与其它常规方法不同之处,在于如何选择包裹体和弹性模型用以计算捕获时的压力条件。准确应用弹性地质压力计的重点在于样品制备、拉曼光谱测量、拉曼光谱处理和弹性模型的建立与选择。同时,本文编制了计算与应用更为便捷的Excel计算表格,将测量石英包裹体的特征拉曼峰峰位直接输入Excel计算表格中即可计算出被捕获时的压力条件。以大别-苏鲁造山带中烟台郭城地区榴辉岩为例,使用弹性地质压力计获得了石榴子石生长的压力史,且与传统地质温压计的结果相对一致。本文提供的方法将为进一步限定相关地质过程中岩石压力记录和变化过程提供新的路径。 Pressure and temperature are critical parameters that characterize the geological processes and form the core of many petrological investigations.Conventional methods to constrain the pressure and temperature conditions of rocks include such as phase equilibria and chemical thermobarometry techniques.These techniques require that the measured minerals have attained chemical equilibrium,which may not be necessarily satisfied in many studied rock samples.A technique,call elastic thermobarometry,utilize the residual stress preserved in sealed mineral inclusions to recover the pressure or temperature conditions when the inclusions were entrapped into the host at depth.The advantage of this technique is that it does not rely on chemical equilibrium and the data can be acquired easily and rapidly to get very reliable pressure and temperature constraints.Currently,the most often applied mineral inclusion-host pair is the quartz-in-garnet pair,which can be used as an elastic geo-barometer to determine the entrapment pressure conditions.However,the application of elastic thermobarometry involves procedures that are different from other conventional thermobarometry methods such as the selection of mineral inclusions and elastic modelling to calculate the entrapment conditions.In this work,we provide a practical introduction on the application of the elastic geo-thermobarometry technique including sample preparation,Raman spectroscopy measurement,Raman spectrum processing and elastic modelling.To simplify the calculation,an Excel spreadsheet is provided that performs the quartz-in-garnet elastic barometry by directly using the measured Raman band position to calculate the final entrapment pressure conditions.An example is given using eclogite samples collected from Sulu-Dabie orogenic belt to recover the garnet crystallization pressure history.The presented method may provide substantial support for the relevant research related to subduction and mountain building processes.

作者仲歆王浩铮冯林峰张华锋陈小宇 JOHN Timm 张丁丁翟明国 ZHONG Xin;WANG HaoZheng;FENG LinFeng;ZHANG HuaFeng;CHEN XiaoYu;JOHN Timm;ZHANG DingDing;ZHAI MingGuo(Institute of Geological Sciences,Freie Universit t Berlin,Berlin 12249,Germany;School of Geoscience and Technology,Southwest Petroleum University,Chengdu 610500,China;School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China;Institute of Geology,China Earthquake Administration,Beijing 100029,China;Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China)

机构地区柏林自由大学地球科学学院西南石油大学地球科学与技术学院中国地质大学(北京)地球科学与资源学院中国地震局地质研究所中国科学院地质与地球物理研究所