The symmetry of garnets on the pyrope (Mg3Al2Si3O12)-majorite (MgSiO3) join
The symmetry of garnets on the pyrope (Mg3Al2Si3O12)-majorite (MgSiO3) join
复制标题
镁铝榴石(Mg3Al2Si3O12)-镁镁石(MgSiO3)连接上石榴石的对称性
DOI：
10.1029/96gl03613
复制
发表时间：
1996
影响因子：
5.2
通讯作者：
R. Liebermann
中科院分区：
文献类型：
--
作者：
J. Parise;Yanbin Wang;G. Gwanmesia;Jianzhong Zhang;Y. Sinelnikov;J. Chmielowski;D. Weidner;R. Liebermann
在 2000 吨单轴分流球装置 (USSA-2000) 中在高压和高温下合成了成分介于多数铁榴石和镁铝榴石之间的石榴石、Mj38、Mj48、Mj75 和 Mj79，并使用高分辨率同步加速器 X 射线粉末衍射和透射电子显微镜进行了研究。两种技术的结果与这些石榴石的四方场一致，延伸至略低于 Mj75 的多数石成分。石榴石中沿多数铁榴石连接的立方-四方结构相变对成分和温度都很敏感，预计会导致弹性剪切模量的异常行为。这种相变可能发生在地幔的过渡带，并对这些石榴石稳定相区域的弹性和流变特性产生重要影响。
Garnets with compositions between majorite and pyrope, Mj38, Mj48, Mj75 and Mj79 were synthesized at high pressures and temperatures in a 2000-ton uniaxial split-sphere apparatus (USSA-2000) and investigated using high resolution synchrotron X-ray powder diffraction and transmission electron microscopy. The results from both techniques are consistent with the tetragonal field for these garnets extending to a majorite composition just below Mj75. The cubic-tetragonal structural phase transition in garnet along the majorite-pyrope join is sensitive to both composition and temperature and is expected to result in anomalous behavior in elastic shear moduli. This phase transition may occur in the transition zone of the earth's mantle and will have important effects on the elastic and rheological properties of this region where these garnets are stable phases.