Phase Equilibria and Crystal-Chemistry of Some Calcic Amphiboles

该项目将从宏观和微观两个方面研究Al取代钙质角闪石在压力、温度和地层组成条件变化下的反应。透晶石型角闪孔中Al含量的变化为测试和完善H2O-CaO-MgO-Al2O3- SiO2体系中角闪孔的热力学混合特性提供了更广泛的数据基础。Fe-Tschermak取代的研究将寻求量化Fe2+和Al与天然钙角闪石之间的强相关性。通过检查沿连接透闪石-辉闪石的体积组成关系来研究放线石-角闪石混溶间隙的压力依赖性，这是一种近似于放线石-角闪石“连接”的方法。本文将利用MAS-NMR、IR和XRD Rietveld技术对合成角闪石中Al的分布进行详细的研究。这一信息将有助于从钙质角闪石的现有数据中提取铝的热化学混合特性。

9316079 Jenkins This project will examine both macroscopic and microscopic aspects of the substitution of Al into calcic amphiboles in response to variations in the pressure, temperature, and compositional conditions of formation. Variations in the Al content of tremolitic amphibole should provide a wider data base for testing and refining the thermodynamic mixing properties of amphiboles in the system H2O-CaO-MgO-Al2O3- SiO2. Research on Fe-Tschermak's substitution will seek to quantify the strong correlation observed between Fe2+ and Al and natural calcic amphiboles. The pressure dependency of the actinolite-hornblende miscibility gap will be investigated by examining the volume-composition relationships along the join tremolite-pargasite, which serves as an approximation to the actinolite-hornblende "join". Considerable attention will be devoted to the detailed examination of Al distribution in synthetic amphiboles by using MAS-NMR, IR and XRD Rietveld techniques. This information will facilitate the extraction of thermochemical mixing properties of Al from available data on calcic amphiboles.