...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Contributions to Mineralogy and Petrology >Cordierite formation during the experimental reaction of plagioclase with Mg-rich aqueous solutions
【24h】

Cordierite formation during the experimental reaction of plagioclase with Mg-rich aqueous solutions

机译：斜长石与富镁水溶液的实验反应过程中堇青石的形成

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

The reaction between plagioclase (labradorite and oligoclase) and Mg-rich aqueous solutions was studied experimentally at hydrothermal conditions (600-700 °C, 2 kbar). During the experiments, plagioclase grains were readily converted to cordierite and quartz within 4 days. The cordierite crystals had well-developed polyhedral shapes, but showed skeletal internal morphologies suggesting that the initial growth occurred fast under high-driving-force conditions. In pure MgCl_2 solutions (0.5-5 M), plagioclase dissolution and cordierite precipitation were spatially uncoupled indicating that Al was to some extent mobile in the fluid. Cordierite crystals formed at 700 °C showed orthorhombic symmetry, whereas those formed at 600 °C dominantly persisted in the metastable hexagonal form suggesting a strong increase in Al, Si ordering speed between 600 and 700 °C. The thermodynamic evolution of the fluid-solid system ultimately resulted in stabilization of Ca-rich plagioclase as demonstrated by partial anor-thitization of unreacted plagioclase grains. Cordierite was also observed to form when Mg was added to a potentially albitizing Na-silicate-bearing solution. In that case, cordierite precipitation appeared to be more closely coupled to plagioclase dissolution, and secondary alteration of remnant plagioclase grains did not occur most likely due to armoring of the plagioclase by the cordierite overgrowth. Thefast reaction rates observed in our experimental study have potential implications for Mg-metasomatism as a rock-forming process.
机译：在水热条件下（600-700°C，2 kbar），通过实验研究了斜长石（拉长石和低聚长石）与富含Mg的水溶液之间的反应。在实验过程中，斜长石晶粒在4天内容易转变为堇青石和石英。堇青石晶体具有发达的多面体形状，但显示出骨骼内部形态，这表明初始生长在高驱动力条件下快速发生。在纯MgCl_2溶液（0.5-5 M）中，斜长石溶解和堇青石沉淀在空间上不耦合，表明Al在一定程度上可在流体中移动。在700°C形成的堇青石晶体显示出斜方晶对称性，而在600°C形成的堇青石晶体则主要以亚稳态六边形形式持续存在，这表明Al和Si的有序速度在600至700°C之间有很大增加。流体-固体系统的热力学演化最终导致富含Ca的斜长石稳定，这通过未反应的斜长石晶粒的部分抗硫醇化证明。当将Mg添加到潜在的可仲裁化的Na-硅酸盐溶液中时，也观察到堇青石形成。在那种情况下，堇青石的沉淀似乎与斜长石溶解更紧密相关，并且由于堇青石的过度生长而使斜长石铠装，因此残留的斜长石晶粒极不可能发生二次改变。在我们的实验研究中观察到的快速反应速率对镁的致突变作用是一个成岩过程的潜在影响。

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