Center for Analysis and Prediction, China Seismological Bureau, Beijing 100036, China 2) Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China
1 Introduction In contrast,1experimental geochemistry is a young subject,but in recent years,the research on experiment of high temperature and high pressure has become an important branch in the parallel subjects of ...1 Introduction In contrast,1experimental geochemistry is a young subject,but in recent years,the research on experiment of high temperature and high pressure has become an important branch in the parallel subjects of traditional mineralogy,petrology,geochemistry and geophysics.It is not only an important and essential way and window to understand geological processes in depth and geological展开更多
Hydrous minerals are important water carriers in the crust and the mantle, especially in the subduction zone. With the recent development of the experimental technique, studies of the electrical conductivity of hydrou...Hydrous minerals are important water carriers in the crust and the mantle, especially in the subduction zone. With the recent development of the experimental technique, studies of the electrical conductivity of hydrous silicate minerals under controlled temperature, pressure and oxygen fugacity, have helped to constrain the water distribution in the Earth's interior. This paper introduces high pressure and temperature experimental study of electrical conductivity measurement of hydrous minerals such as serpentine, talc, brucite, phase A, super hydrous phase B and phase D, and assesses the data quality of the above minerals. The dehydration effect and the pressure effect on the bulk conductivity of the hydrous minerals are specifically emphasized. The conduction mechanism of hydrous minerals and the electrical structure of the subduction zone are discussed based on the available conductivity data. Finally, the potential research fields of the electrical conductivity of hydrous minerals is presented.展开更多
Silicon-bearing rutile has been found in chromitite from the Luobusa （罗布莎） ophiolite, Tibet. However, the extent of SiO2 solubility in rutile and the nature of its origin are still unclear. At high pressure, SiO2...Silicon-bearing rutile has been found in chromitite from the Luobusa （罗布莎） ophiolite, Tibet. However, the extent of SiO2 solubility in rutile and the nature of its origin are still unclear. At high pressure, SiO2 takes a rutile structure with Si in 6-fold coordination. Thus, high pressures may enhance its solubility in rutile because of possible isovalent exchange in the octahedral site. In this study, we report new experimental results on SiO2 solubility in rutile up to 23 GPa and 2 000℃. Starting materials were mixtures of powdered pure rutile and pure quartz, with compositions of （Ti0.5Si0.5）O2, （Ti0.93Si0.07）O2, and （Ti0.75Si0.25）O2. The mixtures were loaded into either platinum capsules （for a 10/5 assembly） or rhenium capsules （for an 8/3 assembly）. The experiments were carried out using multi-anvil high-pressure apparatus with a rhenium resistance heater. Sample temperatures were measured with a W5%Re-W26%Re thermocouple and were controlled within ±1 ℃ of the set temperature. TiO2-rich and SiO2-rich phases were produced in all the quenched samples. Microprobe analyses of the phases show that the solubility of SiO2 in rutile increases with increasing pressure, from 1.5 wt.% SiO2 at 10 GPa to 3.8 wt.% SiO2 at 23 GPa at a temperature of 1 800 ℃. The solubility also increases with increasing temperature from 0.5 wt.% SiO2 at 1 500 ℃ to 4.5 wt.% SiO2 at 2 000 ℃ at a pressure of 18 GPa. On the other hand, the solubility of TiO2 in coesite or stishovite is very limited, with an average of 0.6 wt.% TiO2 over the experimental P-T ranges. Temperature has a much larger effect on the solubility of SiO2 in ruffle than pressure. At high pressure, the melting point of SiO2 is definitely higher than that of TiO2 and the eutectic point moves towards SiO2 in the TiO2-SiO2 system. Lower oxygen fugacity decreases the solubility of SiO2 in ruffle, whereas water has little effect on the solubility. Our experimental data are extremely useful for determining the depth of origin of the SiO2-bearing rutfle found in nature.展开更多
基金State Natural Science Foundation of China (10032040 and 49874013).
文摘Center for Analysis and Prediction, China Seismological Bureau, Beijing 100036, China 2) Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China
基金project was jointly funded by the Funds for the program of the National Natural Science Foundation (Noes. 41572060, U1133602)Projects of YM Lab (2011)Innovation Team of Yunnan province and KMUST (2008,2012)
文摘1 Introduction In contrast,1experimental geochemistry is a young subject,but in recent years,the research on experiment of high temperature and high pressure has become an important branch in the parallel subjects of traditional mineralogy,petrology,geochemistry and geophysics.It is not only an important and essential way and window to understand geological processes in depth and geological
基金supported by the National Natural Science Foundation of China(Grant Nos.41590623&41472040)the Fundamental Research Funds for the Central Universities+2 种基金China University of Geosciences(Grant No.CUGL150801)Special Fund from the State Key Laboratory of Geological Processes and Mineral ResourcesChina University of Geosciences(Grant No.MSFGPMR201408)
文摘Hydrous minerals are important water carriers in the crust and the mantle, especially in the subduction zone. With the recent development of the experimental technique, studies of the electrical conductivity of hydrous silicate minerals under controlled temperature, pressure and oxygen fugacity, have helped to constrain the water distribution in the Earth's interior. This paper introduces high pressure and temperature experimental study of electrical conductivity measurement of hydrous minerals such as serpentine, talc, brucite, phase A, super hydrous phase B and phase D, and assesses the data quality of the above minerals. The dehydration effect and the pressure effect on the bulk conductivity of the hydrous minerals are specifically emphasized. The conduction mechanism of hydrous minerals and the electrical structure of the subduction zone are discussed based on the available conductivity data. Finally, the potential research fields of the electrical conductivity of hydrous minerals is presented.
基金supported by the National Basic Research Program of China (No. 2003CB716503)China Geological Survey (No. 1212010610107)+1 种基金the National Natural Science Foundation of International Cooperation and Communication (No. 40610098)the Laboratory Foundation of the Chinese Academy of Geological Sciences (No. JB0703)
文摘Silicon-bearing rutile has been found in chromitite from the Luobusa （罗布莎） ophiolite, Tibet. However, the extent of SiO2 solubility in rutile and the nature of its origin are still unclear. At high pressure, SiO2 takes a rutile structure with Si in 6-fold coordination. Thus, high pressures may enhance its solubility in rutile because of possible isovalent exchange in the octahedral site. In this study, we report new experimental results on SiO2 solubility in rutile up to 23 GPa and 2 000℃. Starting materials were mixtures of powdered pure rutile and pure quartz, with compositions of （Ti0.5Si0.5）O2, （Ti0.93Si0.07）O2, and （Ti0.75Si0.25）O2. The mixtures were loaded into either platinum capsules （for a 10/5 assembly） or rhenium capsules （for an 8/3 assembly）. The experiments were carried out using multi-anvil high-pressure apparatus with a rhenium resistance heater. Sample temperatures were measured with a W5%Re-W26%Re thermocouple and were controlled within ±1 ℃ of the set temperature. TiO2-rich and SiO2-rich phases were produced in all the quenched samples. Microprobe analyses of the phases show that the solubility of SiO2 in rutile increases with increasing pressure, from 1.5 wt.% SiO2 at 10 GPa to 3.8 wt.% SiO2 at 23 GPa at a temperature of 1 800 ℃. The solubility also increases with increasing temperature from 0.5 wt.% SiO2 at 1 500 ℃ to 4.5 wt.% SiO2 at 2 000 ℃ at a pressure of 18 GPa. On the other hand, the solubility of TiO2 in coesite or stishovite is very limited, with an average of 0.6 wt.% TiO2 over the experimental P-T ranges. Temperature has a much larger effect on the solubility of SiO2 in ruffle than pressure. At high pressure, the melting point of SiO2 is definitely higher than that of TiO2 and the eutectic point moves towards SiO2 in the TiO2-SiO2 system. Lower oxygen fugacity decreases the solubility of SiO2 in ruffle, whereas water has little effect on the solubility. Our experimental data are extremely useful for determining the depth of origin of the SiO2-bearing rutfle found in nature.
