Phase Equilibria and Crystal-Chemistry of Some Calcic Amphiboles

9628212 Jenkins提出了几个项目，以在宏观和微观层面审查角闪石作为其宿主地质地体的压力、温度和化学史指示器的定量使用的关键问题。(1)铁阳起石在CaO-FeO-SiO_2-H_2O体系中的基本性质研究，以确定在M(4)位上是否存在大量的Fe+2取代Ca，以及通过Fe-Tschermaks取代考察Al在铁阳起石中的取代程度，以检验Fe+2对Al在闪石中的溶解度的影响。(2)研究矿物组合(含碳酸盐与不含碳酸盐)的整体化学和角闪石本身(透闪石-透闪石连接)在产生链宽缺陷或变成分角闪石前驱体中的重要性。(3)确定角闪石的八面体和四面体位置上铝的分布。氧化态将通过湿化学或穆斯堡尔谱确定，晶体结构将通过X-射线Rietveld精细化确定。原子结构的直接分析将通过HRTEM进行。

9628212 Jenkins Several projects are proposed to examine at the macroscopic and microscopic levels key issues dealing with the quantitative use of amphiboles as indicators of pressure, temperature and chemical history of their host geologic terrane. These include: (1) Basic characterization studies on ferro-actinolite in the system CaO-FeO-SiO2-H2O to determine whether or not there is substantial substitution of Fe+2 for Ca on the M(4) site and investigation of the extent of Al substitution into ferro-actinolite via the Fe-tschermaks substitution to test the influence of Fe+2 on the solubility of Al into amphibole. (2) An investigation of the importance of the bulk chemistry of the mineral assemblage (carbonate-bearing vs. non-carbonate-bearing) and of the amphibole itself (tremolite-pargasite join) in the production of chain-width defects or variable-composition amphibole precursors. (3) An investigation to determine the distribution of Al on the octahedral and tetrahedral sites of amphibole. Oxidation states will be determined via wet chemistry or M ssbauer spectroscopy and of crystal structure via x-ray Rietveld refinement. Direct analysis of the atomic structure will be done via HRTEM.