The early stage of the crustal foumation in the solar system

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The evolution of crust in the solar system was investigated. The most primitive crust can be represented by eucrites, the intermediately progressed crust by lunar highland anorthosite and the most progressed one by the earth. However, the early earth's crust was almost lost because of extensive colcanic and tectonic activities of the earth.We selected ;as eucrites : ALH85001, Moore County, Serra de Mage, Moamaas Lunar highland anorthosite ; Lunar 76335as an archean anorthosite : BVL19b from Canadian shield and Ylamaa.The diffuse scattereing of c-reflections of plagioclase is sensitive to the cooling rate in the temperature range of 800-200ﾟC.We measured the profiles of c-reflections using X-ray diffraction with lmaging Plate and from the half-hight-width of the profile, the size of c-domain was calculated.The most important result was that Lunar 76335 showed the largest domain size. In the archean anorthosite (BVL19B), the trace of alteration of Precambrian age was found. the alteration products were chlorite and zoisite. They grew along the cleavage plane of host plagioclase and retained the crystallographic orientation, which could be interpreted as the result of graphoepitaxy.