An Experimental Study on the Origin and Dynamics of the Earth's Lower Mantle

地球下地幔起源和动力学的实验研究

基本信息

批准号：
13852005
负责人：
ITO Eiji
金额：
$ 64.06万
依托单位：
Okayama University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (S)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2004
项目状态：
已结题

项目摘要

We have established a technique to generate pressure up to 60 GPa over a specimen volume 2 mm^3 within a repeatable accuracy of 2% using the Kawai-type multi anvil apparatus equipped with sintered diamond cubic anvils with edge length of 14 mm and a truncated corner of 1.5 mm. The maximum pressure reaches higher than 63 GPa. We carried out determination of phase equilibria of several materials under high-pressure and high-temperature by means of in situ X-ray observation using synchrotron radiation at Spring-8. First we examined iron up to 44 GPa and 2100 K. The stability of β-Fe was excluded, and the phase boundary for the ε【tautomer】γ transition was established. We further studied the phase equilbria of GaN and Fe_2O_3 up to 62GPa/900K and 58GPa/1400K, respectively, together with measurement of electrical resistance at 300 K. In GaN, the wurtzire-rocksalt transition was observed at 54GPa/300K and 51.5GPa/750K, suggesting the phase boundary with a negative slope. It was confirmed that … More Fe_2O_3 hematite (phase I) transforms successively into Rh_2O_3II type (II) and an orthorhombic phase (III) with increasing pressure. Both the phase boundaries for the I【tautomer】II, II【tautomer】III have negative slopes. The electrical resistance of GaN was in several tens of mega ohms up to 62 GPa and did not show any remarkable change on the wurtzite-rocksalt transition. The electrical resistance of Fe_2O_3, on the other hand, decreased monotonically from several hundreds mega ohms at 0 GPa to a few ohms at 58 GPa. However, the decrease over a pressure range 54±1 GPa was characteristically abrupt, ca. four orders of magnitude, which can serve as a new pressure fixed point.In order to simulate material fractionation in a magma ocean formed in the early stage of the Earth, we performed melting experiments on peridotite and CI mantle material up to 35 GPa. In peridotite the first liquidus phase changes from feropericlase (Fp) to Mg-perovskite (Mg-Pv) and at 33 GPa liquidus Mg-Pv is successively followed down temperature by Fp and Ca-perovskite (Ca-Pv) within a small temperature interval. In CI mantle material, Mg-Pv is also the liquidus phase followed down temperature by Ca-Pv. These results suggest fractionation of both Mg-Pv and Ca-Pv in a deep magma ocean resulting in formation of a perovskite layer in bottom of the mantle. The layer may be a geochemical reservoir due to the high capability of Ca-Pv to accommodate large cations such as alkaline and rare earth elements.We have successively synthesized single crystals with mm size of deep mantle materials such as Mg-Pv. These crystals are to be used for measurements of elasticity and various transport phenomena such as element and thermal diffusivilitisand electrical conductivity. Less

我们已经建立了一种技术，可以在2 mm^3的标本体积上产生高达60 GPA的压力，在2％的可重复精度为2％内，使用kawai型多砧式设备等效，烧结的钻石立方体虫针，边缘长度为14 mm，截面角为1.5 mm。最大压力达到63 GPA。我们通过使用spring-8的同步辐射来确定高压和高温下几种材料的相等相等。首先，我们检查了高达44 GPA和2100 K的铁。排除了β-FE的稳定性，并建立了ε【互变符】γγ转变的相边界。我们进一步研究了GAN和Fe_2O_3的相位相等脑，分别为62GPA/900K和58GPA/1400K，以及300 K处的电阻的测量，在GAN中，在GAN中，在54GPA/300K/300K和51.5GPA/750中，wurtzire-rocksalt Transition被观察到了一个the the Wurtzire-Rocksalt Transition。已经证实，更多的FE_2O_3赤铁矿（I阶段）成功地转化为RH_2O_3II类型（II）和正骨相（III），并随着压力的增加而变化。 I【互变异者】II，II次互变异者】III的两个相边界都有负插槽。 GAN的电阻为几十欧姆，最高为62 GPa，并且没有显示出Deadzite-Rocksalt Transition的显着变化。另一方面，Fe_2O_3的电阻从0 GPA时的数百个巨型欧姆单调降低到58 GPA时的几个欧姆。然而，压力范围54±1 GPA的降低特征是突然的。四个数量级，可以用作新的压力固定点。为了模拟在地球早期形成的岩浆海洋中的材料分馏，我们对橄榄岩和CI地幔材料进行了熔化的实验，最高35 GPA。在橄榄岩中，第一个液化相位从铁磷酸酯酶（FP）变为Mg-perovskite（MG-PV），在33 GPA的情况下，在较小温度间隔内通过FP和Ca-Perovskite（Ca-Perovskite（Ca-PV））成功地降低了温度。在CI地幔材料中，MG-PV也是液相液相通过CA-PV的降低温度。这些结果表明，在深岩浆海洋中，MG-PV和CA-PV分离，导致地幔底部的钙钛矿层形成。由于CA-PV能够容纳大型阳离子，例如醇和稀土元素，因此该层可能是地球化学晶状体。我们成功合成了具有MM大小的深幔材料（例如MG-PV）的单晶。这些晶体应用于测量弹性和各种转运现象，例如元素和热延伸性炎和电导率。较少的