• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of Metamorphic Geology >Transforming mylonitic metagranite by open-system interactions during melt flow
【24h】

Transforming mylonitic metagranite by open-system interactions during melt flow

机译：在熔体流动过程中通过开放系统相互作用转变my质变质花岗岩

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Gneisses and migmatites of the Gfohl unit (Moldanubian Zone, Bohemian Massif) range from banded mylonitic orthogneiss with recrystallized monomineralic bands, through stromatic (metatexite) and schlieren (inhomogeneous diatexite) migmatite, to isotropic nebulite (homogeneous diatexite). This sequence was classically attributed to increasing degree of anatexis. Under the microscope, the evolution is characterized by progressive destruction of the monomineralic banding that characterizes the original mylonitic orthogneiss. Throughout, the mineral assemblage is biotite-K-feldspar-plagioclase-quartz +/- garnet +/- sillimanite, but the mineral compositions exhibit systematic changes with progressive disintegration of the layering. From banded orthogneiss to nebulite, the garnet composition changes systematically, Alm(75 -> 94)Prp(17 -> 0.8)Grs(2.5 -> 1.2)Sps(2 -> 11) and X-Fe = 0.45 -> 0.99 and for biotite, X-Fe = 0.80 -> 1. This is consistent with a decrease in equilibration temperature and pressure of 790 degrees C and 8.5-6 kbar, to 690 degrees C and 5-4 kbar respectively. There is also a systematic change of whole-rock composition, marked by an increase in SiO2 (71 -> 77 wt%) and X-Fe (0.62 -> 0.85) and by a decrease in Al2O3 (16 -> 13 wt%) and CaO (1.50 -> 0.43 wt%). Assuming that the rocks started with the same composition, these systematic changes indicate open-system behaviour. The predicted consequences of various open-system processes are assessed using thermodynamic modelling. The observed variations are interpreted as being a consequence of melt flow through, and interaction with the rocks, and, to change the rock composition sufficiently, a large volume of melt must have been involved.
机译：Gfohl单元（波西米亚地块的Moldanubian区）的片麻岩和蒙脱石的范围从带重结晶单矿物带的带条带的似斜长片麻片岩到层状（蒙脱石）和schlieren（非均质透辉石）蒙脱石，到各向同性云母（均质透辉石）。该序列经典地归因于厌食症程度的增加。在显微镜下，这种进化的特征是逐渐破坏了原始矿物性直生片麻岩的单矿物带。在整个过程中，矿物组合是黑云母-钾长石-斜长石-石英+/-石榴石+/-硅线石，但是随着分层的逐步崩解，矿物组成表现出系统的变化。从带状的片麻片到雾状，石榴石的成分都会系统地变化，Alm（75-> 94）Prp（17-> 0.8）Grs（2.5-> 1.2）Sps（2-> 11）和X-Fe = 0.45-> 0.99，对于黑云母，X-Fe = 0.80->1。这与平衡温度和压力分别从790摄氏度和8.5-6 kbar降低到690摄氏度和5-4 kbar一致。整个岩石组成也有系统的变化，其特征在于SiO2（71-> 77 wt％）和X-Fe（0.62-> 0.85）的增加以及Al2O3（16-> 13 wt％）的减少CaO（1.50-> 0.43 wt％）。假设岩石以相同的成分开始，那么这些系统的变化表明了开放系统的行为。使用热力学建模可以评估各种开放系统过程的预测结果。观察到的变化被解释为熔体流过岩石并与岩石相互作用的结果，并且要充分改变岩石成分，必须涉及大量的熔体。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号