Phase relations and melting in the system CaCO3 und MgCO3 at high pressures and temperatures

CaCO3 和 MgCO3 体系在高压和高温下的相关系和熔化

• 批准号: 390971151
• 负责人: Professorin Dr. Monika Koch-Müller
• 金额: --
• 依托单位: Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum (GFZ)
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/390971151?language=en
• 关键词: Phase; relations; melting; system; CaCO3

Calcite and magnesite are among the most common carbonates of the Earth. A deeper insight into the phase relations and melting behavior of the anhydrous and hydrous CaCO3 and MgCO3 system is crucial to understand the carbon cycle in the Earth mantle and project 8 of the Research Unit is dealing with this topicThe project is devided in three parts:In part 1 we will determine of the melting curve of magnesite under anhydrous conditions in the pressure range of 4 to 13 GPa by in situ measurements of the electrical conductivity change in a multi anvil press when magnesite melts. In part 2 we will determine the sub and super solidus phase relations of the CaCO3 and MgCO3 system at 9 GPa and high temperature (starting from 900 C) by quenched multi anvil runs under anhydrous conditions and then establish the phase relations in the super solidus P, T space of the hydrous CaCO3 and MgCO3 system. We will use a rotating multi anvil press to overcome quenching problems as observed in previous studies.In part 3 we will examine the pressure dependence of the melting curve of magnesite under hydrous conditions by means of in situ X ray diffraction measurements with the newly installed multi anvil apparatus at the synchrotron storage ring PETRA III in Hamburg. Here melting at high pressures and temperatures will be established by the occurrence of diffuse scattering in the X ray diffraction pattern.This different experimental approach to determine the melting relation in the hydrous system is necessary as the presence of water would falsify the results on the electrical conductivity.

方解石和菱镁矿是地球上最常见的碳酸盐。更深入地了解无水和含水 CaCO3 和 MgCO3 系统的相关系和熔化行为对于理解地幔中的碳循环至关重要，研究小组的项目 8 正在处理这个主题该项目分为三个部分：第 1 部分，我们将通过现场测量多砧压机中的电导率变化，确定在 4 至 13 GPa 压力范围内的无水条件下菱镁矿的熔化曲线。菱镁矿熔化。在第 2 部分中，我们将通过在无水条件下淬火多砧运行来确定 CaCO3 和 MgCO3 系统在 9 GPa 和高温（从 900 C 开始）下的亚固相线和超固相线相关系，然后建立超固相线 P 中的相关系，含水 CaCO3 和 MgCO3 体系的 T 空间。我们将使用旋转多砧压力机来克服先前研究中观察到的淬火问题。在第 3 部分中，我们将通过使用新安装的多砧压力机进行原位 X 射线衍射测量来检查含水条件下菱镁矿熔化曲线的压力依赖性。汉堡同步加速器存储环 PETRA III 上的砧装置。这里，通过 X 射线衍射图案中漫散射的发生，将建立高压和高温下的熔化。这种确定含水系统中熔化关系的不同实验方法是必要的，因为水的存在会伪造电学结果。电导率。