An experimental study of effect of pre-existing fabric on deformation of foliated mylonite at high temperature and pressure
An experimental study of effect of pre-existing fabric on deformation of foliated mylonite at high temperature and pressure
复制标题
高温高压下预存织物对叶状糜棱岩变形影响的实验研究
DOI：
10.1002/gj.2611
复制
发表时间：
2016
影响因子：
1.8
通讯作者：
Zhang Yuanyuan
中科院分区：
文献类型：
--
作者：
Liu Gui;Zhou Yongsheng;He Changrong;Yao Wenming;Liu Junlai;Zhang Yuanyuan
对一片理化糜棱岩进行了高温高压条件下的变形实验。为了研究预先存在的组构对岩石流变学的影响，我们的样品从天然糜棱岩中钻取，圆柱轴平行于叶理（PAR）和垂直于叶理（PER）。我们对7个PAR样品和7个PER样品分别进行了25次和21次试验，试验温度范围为600至890 °C，围压范围为800至1400 MPa，稳态应变速率为1 × 10−4、1 × 10− 5和2.5 × 10−6s−1。在600-700 °C的温度范围内，变形以半脆性流动为主，平均应力指数为6-7，呈幂律流动;在800-890 °C的温度范围内，变形以塑性流动为主，平均应力指数n = 3，激活能Q = 354 ± 52 kJ/mol（PER和PAR样品）。实验结果表明，PER样品的强度高于PAR样品。用光学显微镜和电子显微镜研究了变形显微组织。PER样品的原始叶理被变形破坏并被新的叶理所取代，而PAR样品的变形遵循原始叶理。电子背散射衍射（EBSD）的测量结果表明，强的晶格择优取向（LPO）的石英轴织物的起始样品和变形PER和PAR样品。然而，实验变形PER和PAR样品中的石英的轴向组构随温度和应变速率而变化，与初始糜棱岩样品中所见的不同。在实验变形过程中，初始糜棱岩样品的初始石英轴组构已转化为新组构。PER和PAR样品中的黑云母和角闪石在800-890 °C的温度下发生脱水熔融。版权所有© 2014约翰威利父子有限公司.
We performed deformation experiments on a foliated mylonite under high temperature and pressure conditions in this study. To investigate the effect of pre‐existing fabric on the rheology of rocks, our samples were drilled from natural mylonite with the cylinder axis parallel to the foliation (PAR) and perpendicular to the foliation (PER). We performed 25 tests on seven PAR samples and 21 tests on seven PER samples at temperatures ranging from 600 to 890 °C, confining pressures ranging from 800 to 1400 MPa, and steady‐state strain rates of 1 × 10−4, 1 × 10−5and 2.5 × 10−6s−1. In the temperatures of 600–700 °C, the deformation is accommodated by semi‐brittle flow, with the average stress exponent being 6–7 assuming power law flow; in the temperature range of 800–890 °C, deformation is mainly by plastic flow, with an average stress exponent ofn= 3 and activation energies ofQ= 354 ± 52 kJ/mol (PER and PAR samples). The experimental results show that the strengths of PER samples are higher than those of PAR samples. Deformation microstructures have been studied by optical and electron microscopy. The original foliation of PER samples is destroyed by deformation and replaced by a new foliation, but the deformation of PAR samples followed the original foliation. Electron backscatter diffraction (EBSD) measurements show a strong lattice preferred orientation (LPO) of the quartzcaxis fabrics of the starting samples and deformed PER and PAR samples. However, thecaxis fabric of quartz in experimentally deformed PER and PAR samples varied with temperature and strain rate is different from that seen in the starting mylonite sample. The initial quartzcaxis fabric of the starting mylonite sample has been transformed into a new fabric during experimental deformation. Dehydration melting of biotite and hornblende occurred in both PER and PAR samples at temperatures of 800–890 °C. Copyright © 2014 John Wiley & Sons, Ltd.