...
  • 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 >Phase relations of phlogopite with magnesite from 4 to 8 GPa
【24h】

Phase relations of phlogopite with magnesite from 4 to 8 GPa

机译：金刚砂与菱镁矿在4至8 GPa的相关系

获取原文
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

To evaluate the stability of phlogopite in the presence of carbonate in the Earth’s mantle, we conducted a series of experiments in the KMAS–H2O–CO2 system. A mixture consisting of synthetic phlogopite (phl) and natural magnesite (mag) was prepared (phl90-mag10; wt%) and run at pressures from 4 to 8 GPa at temperatures ranging from 1,150 to 1,550°C. We bracketed the solidus between 1,200 and 1,250°C at pressures of 4, 5 and 6 GPa and between 1,150 and 1,200°C at a pressure of 7 GPa. Below the solidus, phlogopite coexists with magnesite, pyrope and a fluid. At the solidus, magnesite is the first phase to react out, and enstatite and olivine appear. Phlogopite melts over a temperature range of ~150°C. The amount of garnet increases above solidus from ~10 to ~30 modal% to higher pressures and temperatures. A dramatic change in the composition of quench phlogopite is observed with increasing pressure from similar to primary phlogopite at 4 GPa to hypersilicic at pressures ≥5 GPa. Relative to CO2-free systems, the solidus is lowered such, that, if carbonation reactions and phlogopite metasomatism take place above a subducting slab in a very hot (Cascadia-type) subduction environment, phlogopite will melt at a pressure of ~7.5 GPa. In a cold (40 mWm−2) subcontinental lithospheric mantle, phlogopite is stable to a depth of 200 km in the presence of carbonate and can coexist with a fluid that becomes Si-rich with increasing pressure. Ascending kimberlitic melts that are produced at greater depths could react with peridotite at the base of the subcontinental lithospheric mantle, crystallizing phlogopite and carbonate at a depth of 180–200 km.
机译：为了评估地幔中碳酸盐存在时金云母的稳定性，我们在KMAS–H 2 O–CO 2 系统中进行了一系列实验。制备了由合成金云母（phl）和天然菱镁矿（mag）组成的混合物（phl 90 -mag 10 ; wt％），并在4至8 GPa的压力下运行在1,150至1,550°C的温度范围内。我们将固相线分别在1,4,5和6 GPa的压力下在1,200和1,250°C之间以及在7 GPa的压力下的1,150和1,200°C之间进行了包围。在固相线以下，金云母与菱镁矿，pyrope和液体共存。在固相线中，菱镁矿是第一个反应出的相，顽辉石和橄榄石出现。金云母在约150°C的温度范围内熔化。石榴石的数量从固相线以上增加，从〜10模态％增加到〜30模态％，直至压力和温度升高。随着压力的增加，从接近4 GPa的原始金云母到压力≥5 GPa的高硅硅，淬火金云母的组成发生了巨大变化。相对于不含CO 2 的系统，固相线降低，因此，如果碳酸化反应和金云母交代发生在非常热（卡斯卡迪亚型）俯冲环境中的俯冲平板上方，金云母就会熔化压力约为7.5 GPa。在寒冷的（40 mWm −2 ）次大陆岩石圈地幔中，金云母在碳酸盐存在的情况下稳定到200 km的深度，并且可以与随着压力增加而富硅的流体共存。在更深的深度产生的上升的金伯利岩熔体可能与亚大陆岩石圈地幔底部的橄榄岩发生反应，在180-200 km的深度使金云母和碳酸盐结晶。

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