作者: R. H. Jones , E. R. D. Scott
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摘要: Detailed petrologic studies have been made of 15 type IA, Fe-poor, porphyritic olivine chondrules in Semarkona (LL3.0). Major and minor element concentrations olivines, pyroxenes, mesostases, bulk composition so the are measured along with zoning profiles pyroxene crystals. The mineral compositions textures best interpreted terms closed system crystallization which olivines pyroxenes crystallized situ from a melt corresponding to chondrule. Relict grains not found chondrules. Crystallization probably occurred at cooling rate order 1000 C/hr. Precursor materials were composed two components, one refractory Ca-, Al-, Ti-rich, less Si-, Fe-, Cr-, Mn-rich. evidence is consistent being least metamorphosed ordinary chondrites.