The cation distribution of major and minor elements over the two non-equivalent sites in olivine and its temperature dependence.

橄榄石中两个非等价位点上主量元素和微量元素的阳离子分布及其温度依赖性。

基本信息

批准号：
02453050
负责人：
MATSUMOTO Takeo
金额：
$ 3.46万
依托单位：
Kanazawa University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

项目摘要

The cation distribution coefficients K_D (=(Fe/Mg)_<M1>/(Fe/Mg)_<M2>) were calculated from the X-ray site occupancy refinements for olivines. The K_D values of Mg, Feolivines obtained are 0.95-1.13 in basalt, 1.01-1.12 in ultramafic nodule, 1.18 in rhyolite, 0.95 in metamorphic rocks atid 0.91 in H6-chondolite. As a whole, the volcanic olivines have the slight preference of Fe for the Ml site, and the metamorphic olivines for the M2 site, as the previous investigators reported.In-situ high temperature X-ray experiments showed that the K_D values of the heated olivines increased with increasing temperature, and that values above 600 ﾟC increase with increasing fayalite content. Ttiese results suggest that tile cation exchange in olivine is not sluggish at high temperature and the cation distribution at high temperature is not preserved on cooling. Ttierefdre the K_D values at room temperature for olivines are riot obviously distinguished by the modes of occurrence.Using ALHEMI (Atomic Location by CHanneling Enhanced MIcroanalysis) technique, with an Akaslii EM-002B TEM having EDAX9100 and double tilt specimen holder, the distribution of cations over the two cation sites in olivine is determined. A suitable set of planes for electron clianrie. ling is(002)in Pbnm setting. Here, the new equation for the calculation to determine the site occupancies, using Si atom as reference atom, is derived. Mg and Fe show a slight preference for the M2 and M1 sites respectively. Minor elements Ni and Mn show a strong preference for the M1 site and the M2 site respectively.

阳离子分布系数k_d（=（fe/mg）_ <m1>/（fe/mg）_ <m2>）是根据橄榄石的X射线位点占用精炼计算得出的。在玄武岩中获得的Mg的K_d值，获得的feolivines的K_D值为0.95-1.13，超镁铁质结节中的1.01-1.12，在H6--------------------------岩的变质岩石中为0.95，在H6---------------------岩的变质岩石中为0.91。正如先前的研究者所报道的那样，总体而言，火山橄榄石对ML位点具有轻微的Fe偏好，而M2位点的变质橄榄石对M2位置的变质橄榄石。IN-SITU高温X射线实验表明，加热橄榄石的K_D值随着温度的增加而增加，而高于600 c c随着fayalite的含量的增加，加热橄榄石的K_D值随着温度的增加而增加。 TTIESE结果表明，橄榄石中的瓷砖阳离子交换在高温下并不慢，并且在冷却时不能保留高温下的阳离子分布。 ttierefdre在室温下为橄榄石的k_d值显然以出现的模式区分。使用Alhemi（通过引导微分析增强的原子位置）技术，具有Akaslii EM-002B TEM具有EDAX9100的Akaslii EM-002B TEM，并且是双层标本持有人的分布，是cotation consess of tw Citation coliv coliv coliv coliv coliv conses of cocation。电子clianrie的合适平面。 Ling在PBNM设置中为（002）。在这里，得出了使用SI原子作为参考原子来确定位点占用的新方程。 MG和FE分别对M2和M1位点略有偏爱。 NI和MN的次要元素分别表现出对M1位点和M2位点的强烈偏爱。