Experimental Petrology and Geochemistry of Continental Rift Volcanics: Petrogenesis of Evolved, Alkaline Magmas

拟议的研究包括碱玄武岩的实验研究，这些实验研究已被先前的地球化学和反方法实验研究证明是大量的、与裂谷相关的火山活动的母岩。高压和高温正向熔融实验将用于描述这些熔岩形成所必需的过程和地壳内的物理和化学条件。具体的实验目标是：(1)在中地壳到上地幔的压力和温度范围内，确定由碱性玄武岩成分的平衡部分熔融或结晶产生的熔体的液体下降线（分馏路径）；(2)确定在这些压力和温度条件下存在的矿物相的组成；(3)表征剩余相组合（堆积岩性）；(4)比较碱性玄武岩熔融实验与中间成分熔岩液相条件下的相组成。拟议的实验和分析研究的结果将为在地壳条件下评价熔体演化的多压路径提供基础，并使大陆裂谷结构和演化的大陆模式以及地壳参与裂谷过程的大陆模式得以发展。

9316197 Wendlandt The proposed research involves experimental investigations of alkali basalts, demonstrated by previous geochemical and inverse-approach experimental studies to be parental to voluminous, rift-associated, volcanic occurrences. High pressure and temperature forward-approach melting experiments will be used to characterize the processes and the physical and chemical conditions within the crust necessary for the genesis of these lavas. Specific experimental objectives are: (1) to determine liquid lines of descent (fractionation paths) for melts derived by equilibrium partial melting or crystallization of alkali basalt compositions for a range of mid-crustal to upper mantle pressures and temperatures; (2) to determine the compositions of mineral phases present at these pressure and temperature conditions; (3) to characterize residual phase assemblages (cumulate lithologies); and (4) to compare compositions of phases from alkali basalt melting experiments with those documented at liquidus conditions for intermediate composition lavas. The results of the proposed experimental and analytical studies will provide a basis for evaluating polybaric paths for melt evolution at crustal conditions and enable development of integrated models for continental models for continental rift structure and evolution and for the involvement of crust in rifting processes.