New Textures and Minerals in the Meteorite Silao (Cuartaparte) Chondrite H5: a Product of the Impact Metamorphism S4
Keywords:
chondrite, shock features, olivine, fusion, SilaoAbstract
The Silao (also known as Cuarta Parte) meteorite fell down on the 17th, at April 1995 in Cuarta Parte, Silao, Guanajuato, México. Silao is classified as an ordinary chondrite of the H group and type 5. It is compone by olivine, pyroxene, Fe-Ni metals, trolilite, chromite and apatite. Various shock features are recognized in Silao such as veins, fractures and fusion pockets, pyroxenes with planar and dislocated fractures, wavy extinction in olivine and silicate darkening due to fracturing, metal accumulation and mafic glass. Also, associations of chromite-plagioclase, metal spherical morphology, mingling of metals with sulfurs showing textures that indicate sulfuration and metal fusion above the eutectic are observed. These textures are generated by impact metamorphism with a pressure minimum peak greater then 300-350 kbars. In this paper it is presented new mineralogical textures characteristic of shock impact found in this meteorite such as the occurrence of botroidal Cu material, polycrystalline mineral of fine grain euhedral olivine, polycrystalline troilite and glass as fibers with Fe-Ni.
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