• 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 >Experimental determination of quartz solubility and melting in the system SiO2-H2O-NaCl at 15-20 kbar and 900-1100 degrees C: implications for silica polymerization and the formation of supercritical fluids
【24h】

Experimental determination of quartz solubility and melting in the system SiO2-H2O-NaCl at 15-20 kbar and 900-1100 degrees C: implications for silica polymerization and the formation of supercritical fluids

机译：石英溶解度和SiO2-H2O-NaCl在15-20 kbar和900-1100摄氏度下的熔融度的实验确定：对二氧化硅聚合和超临界流体的形成有影响

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

We investigated quartz solubility and melting in the system SiO2-NaCl-H2O at 15-20 kbar and 900-1100 degrees C using hydrothermal piston-cylinder methods. The solubility of natural, high-purity quartz was determined by weight loss. Quartz solubility decreases with increasing NaCl mole fraction (X-NaCl) at fixed pressure and temperature. The decline is greatest at low X-NaCl. The solubility patterns can be explained by changes in the concentration and identity of silica oligomers. Modeling of results at 1000 degrees C, 15 kbar, reveals that silica monomers and dimers predominate at low Si concentration (high X-NaCl), that higher oligomers assumed to be trimers become detectable at X-NaCl = 0.23, and that the trimers contain > 50 % of dissolved Si at X-NaCl = 0. The modeling further implies a hydration number for the silica monomer of 1.6, significantly lower than is observed in previous studies. Results at 15 kbar and 1100 degrees C provide evidence of two coexisting fluid phases. Although solubility could not be determined directly in these cases, the presence or absence of phases over a range of bulk compositions permitted mapping of the topology of the phase diagram. At 1100 degrees C, 15 kbar, addition of only a small amount of NaCl (X-NaCl = 0.05) leads to separation of two fluid phases, one rich in H2O and SiO2, the other rich in NaCl with lower SiO2. Textural identification of two fluids is supported by very low quench pH due to preferential partitioning of Na into the fluid that is rich in SiO2 and H2O, confirmed by electron microprobe analyses. The addition of NaCl causes the upper critical end point on the SiO2-H2O melting curve to migrate to significantly higher pressure. Correspondence between depolymerization and phase separation of SiO2-H2O-NaCl fluids indicates that polymerization plays a fundamental role in producing critical mixing behavior in silicate-fluid systems.
机译：我们使用水热活塞缸法研究了在15-20 kbar和900-1100摄氏度下SiO2-NaCl-H2O系统中的石英溶解度和熔融度。天然高纯度石英的溶解度通过重量损失来确定。在固定压力和温度下，石英溶解度随NaCl摩尔分数（X-NaCl）的增加而降低。在低X-NaCl下，下降幅度最大。溶解度模式可以通过改变二氧化硅低聚物的浓度和特性来解释。在1000摄氏度，15 kbar下对结果进行建模，发现在低Si浓度（高X-NaCl）下，二氧化硅单体和二聚体占主导地位，在X-NaCl = 0.23时可检测到被认为是三聚体的高级低聚物，并且三聚体包含在X-NaCl = 0时> 50％的溶解Si。该模型进一步暗示二氧化硅单体的水合数为1.6，大大低于以前的研究结果。在15 kbar和1100摄氏度下的结果提供了两种流体相共存的证据。尽管在这些情况下无法直接确定溶解度，但在一定体积的整体组成范围内，无论是否存在相，都可以绘制相图拓扑图。在1100摄氏度，15 kbar下，仅添加少量的NaCl（X-NaCl = 0.05）导致两个液相分离，一个液相富集H2O和SiO2，另一个液相富集NaCl和较低的SiO2。通过电子微探针分析证实，由于Na优先分配到富含SiO2和H2O的流体中，因此非常低的淬灭pH值可以支持两种流体的组织结构鉴定。 NaCl的添加会导致SiO2-H2O熔融曲线上的最高临界端点迁移到明显更高的压力。 SiO2-H2O-NaCl流体的解聚和相分离之间的对应关系表明，聚合反应在硅酸盐-流体体系中产生关键的混合行为中起着基本作用。

著录项

相似文献

  • 外文文献
  • 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