| 其他摘要 | Eclogite is a kind of metamorphic rock, which contents the omphctite and garnet more than 80%, and glaucophane some. The samples studied in this paper are collected from the high-pressure metamorphic belts of Dabie Mountains. The main rocks forming minerals of eclogite are researched on high-pressure and high-temperature which is simulating the lower mantle crust condition. The PVT equation of state (EOS) is fitted to calculate the cell volume and bulk modulus and the relation of them. Modeling the relationship between the density of eclogite+ lherzolite and the temperature and pressure. Comparing The density of eclogite+ lherzolite and asthenosphere is compared to get in what condition the delamination may occur. The author uses external resistance heating diamond anvil cell (DAC) combined with synchrotron radiation powder X -ray diffraction method, to study the PVT EOS and PV EOS of four eclogite samples of different components. Combined with previous studies, discussed a series composition change of Pyr-Alm-Grs with their cell volume , bulk modulus and other physical parameters. The results obtained are as follows:1. Analysising the PV EOS of four different components of Pyr-Alm-Grs at room temperature 300K, found that the cell volume decreasing with the content of Pyr increasing. Combined with the previous studies, fitting the relationship of Pyr content and bulk modulus at a series composition change of Pyr-Alm-Grs. According to the relationship , you can estimate the bulk modulus of garnet in the know Pyr-Alm end-member component.2. Researching for garnet samples MW01, SH962 and SM969 HPHT PVT EOS, get zero pressure cell volume , zero-pressure bulk modulus , bulk modulus temperature derivative and the thermal expansion coefficient values. Due to the high temperature conditions fewer data points , the temperature derivative of bulk modulus and the thermal expansion coefficient values are significantly higher than the previous results .3．Fitting four different omphacite samples PV EOS, get zero pressure cell volume, zero-pressure bulk modulus , bulk modulus and temperature conductivity at room temperature 300 K. Combined with results of previous studies , found that there’s no obviously correlationship between contents of pyroxene and the bulk modulus.4. The HTHP elastic data of the Di89Jd11 pyroxene is obtained first time. However, due to fewer data points under high temperature conditions , the temperature derivative of bulk modulus and the thermal expansion coefficient values are 4-6 times the previous research result.5. Combined the EOS data of garnet, omphacite, diopside and enstatite before, with previous research result to build the condition model of under-lithosphere(90-250km, 1250-1350°C). Using that model, you can estimate the density of eclogite , pyrolite mantle rocks and lherzolite. The delamination may occur at the top of the asthenosphere depth of less than 200km after preliminary analysis the model. |
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