Shock metamorphic history of primitive meteorites: experimental approach

(1)实验冲击水合球粒陨石的加热效应：与微陨石的比较：我们通过透射电镜对10-49 GPa实验冲击水合多孔陨石进行了研究，发现其矿物学和结构与微陨石相似。结果表明，微陨石很可能在进入大气层之前经历了小行星撞击时发生的冲击加热过程。(2) CK4球粒陨石中富含微包裹体的囊泡橄榄石：高温冲击的产物：我们的透射电镜研究表明，CK4球粒陨石中含有高丰度的罕见橄榄石，其中含有高密度的亚微米大小的囊泡和多种矿物的包裹体。结果表明，泡状橄榄石是由高温冲击产生的熔体结晶形成的。(3)顽辉石热液蚀变实验：对球粒陨石含水蚀变的启示：在pH 0 ~ 14、100 ~ 300℃、24 ~ 336小时进行顽辉石热液蚀变实验，为含水陨石含水蚀变条件提供约束条件。结果表明，长辉石的蚀变与pH值密切相关，不同类型球粒陨石间层状硅酸盐矿物学差异的主要原因是水溶液pH条件的不同。(4)星尘号返回的怀尔德2号彗星样品的矿物学研究：我们对怀尔德2号彗星样品的透射电镜研究表明，怀尔德2号彗星样品主要由结晶硅酸盐和少量铁镍硫化物和金属组成，其矿物学特征与碳质球粒陨石相似。一颗橄榄石颗粒的纹理表明，Wild2粒子在被捕获之前经历了超高速撞击。

(1) Heating effects of an experimentally shocked hydrated chondrite: Comparison with micrometeorites: Our transmission electron microscope study of a hydrated porous meteorite experimentally shocked at pressures of 10-49 GPa shows that its mineralogy and texture are similar to those of micrometeorites. The results suggest that micrometeorites are likely to have gone through shock heating processes that took place during asteroidal impacts before atmospheric entry.(2) Microinclusion-rich vesicular olivine in CK4 chondrites: A product of shock at high temperature: Our transmission electron microscope study reveals that a CK4 chondrite contains a high abundance of unusual olivine that contains high densities of submicrometer-size vesicles and inclusions of a variety of minerals. The results suggest that the vesicular olivine was formed by crystallization of melts that were produced by shock at a high temperature.(3) Hydrothermal alteration experiments of enstatite: Implications for aqueous alteration in chondrites: Hydrothermal alteration experiments of enstatite were carried out at pH 0-14, at 100-300℃, and for 24-336 hours in order to provide constraints on aqueous alteration conditions of hydrated meteorites. The results indicate that alteration of enstatite is strongly dependent on pH. The results therefore suggest that the differences in phyllosilicate mineralogy among the different types of chondrite mainly resulted from different pH conditions of aqueous solutions.(4) Mineralogical investigation of Comet Wild 2 samples returned by Stardust: Our transmission electron microscope study of comet Wild 2 samples shows that they consist mainly of crystalline silicates and minor amounts of Fe-Ni sulfide and metal, and their mineralogical characteristics are similar to those of the carbonaceous chondrites. One olivine grain has a texture suggesting that the Wild2 particles experienced hypervelocity impacts before capture.