Petrology of magmatic silicate inclusions in the Allan Hills 77005 lherzolitic shergottite

Abstract— Magmatic inclusions occur in both chadacrystic olivine and oikocrystic pigeonite in ALH 77005 but are different from each other. Magmatic inclusions in olivine consist mainly of aluminous pyroxenes, intergrowths of plagioclase and silica, silica-predominant glass, and rhyodacitic glass, with minor amounts of chromite, spinel, pyrrhotite, and whitlockite. Those in pigeonite consist mainly of aluminous pyroxenes, nonaluminous ferroan pyroxenes, kaersutite, spinel, and K-rich trachytic glass, with minor amounts of pyrrhotite and whitlockite. The magmatic inclusions in chadacrystic olivine formed from trapped melts that were basaltic, apparently dry and crystallized additional olivine metastably. The basaltic magma, with entrained olivine, experienced magma mixing with K-rich and wet magmas, or assimilation of such crustal rocks, in the early to middle stages of the crystallization sequence of ALH 77005 during crystallization of chadacrystic olivine prior to precipitation of oikocrystic pigeonite. However the amount of mixed magmas or assimilated rocks was minor in comparison to the basaltic magma. Crystallization of pigeonite, augite, and plagioclase in the host lithologies took place in a shallow magma reservoir under an open-system condition, and the pigeonite trapped basaltic andesite to trachyandesitic melts, which resulted in magmatic inclusions in oikocrystic pigeonite. The magmatic inclusions in both olivine and pigeonite were formed under a rapid-cooling condition, resulting in a variety of inclusions. Kaersutite in magmatic inclusions in oikocrystic pigeonite crystallized under a closed-system wet condition during the late-stage crystallization of the inclusions.     

安装有防屈曲支撑建筑的地震模拟与经济性分析

结合防屈曲支撑拟静力实验的研究成果,用ABAQUS有限元软件模拟一栋建筑的地震反应。比较原设计结构与减少梁柱面积但安装有防屈曲支撑的减缩结构这2种方案下的地震响应,使两者的层间位移角相近并满足规范要求,进而做经济性对比。结果表明,防屈曲支撑可以有效地减小结构地震响应,并且先于梁柱破坏,保护主体结构安全;安装防屈曲支撑的结构在满足设计要求的同时,还可以节省建筑成本,缩短施工工期。