The Confirmation of a New Type of Chondrites and Their Cosmochemical Significance  

作　　者：侯渭 

出　　处：《Chinese Journal Of Geochemistry》1996年第2期100-104,共5页中国地球化学学报

摘　　要：The data available show that some Antarctic caboaceous chondrites are similar toCl meteorites. They contain a lot of phyllorilicate aggregates and the oxygen isotopic composition of the whole-rock samples is approximate to that of Cl chondrites, so they are named afterquasi-Cl (Q-Cl ) chondrites. Unlike Cl metoorites, the Q-Cl chondrites possess chondrulestructure, and the compositions of high-temperature condensates (chondrule fragments, mineral grains or aggregates) show that the oxygen fugacity varied within a wide range in the surroundings where they were formed, similar to the variation range from E-, H-, L-, LL- t0 C-group chondrites. It is inferred that the Q-Cl chondrites could be formed at the edges far fromthe equator in the whole asteroid region of the soar nebular disk, where the nebula was lowerin density and the txindensates were lower in accretion velocity, so that the hydration of chondrules and matrix occurred during the late stage of nebular condensation. The discovery of theQ-Cl chondrites and the fact that the earth and other terrestrial planets contain water indicatethat at the edges far from the erluator in the terrestrial region of the solar nebular disk, a largeamount of water was incorporated into the lattice of minerals in the condensates as a result ofhydration during nebular condensation, and then found its way into the interior parts of theEarth and other terrestrial planets due to accretion.The data available show that some Antarctic caboaceous chondrites are similar toCl meteorites. They contain a lot of phyllorilicate aggregates and the oxygen isotopic composition of the whole-rock samples is approximate to that of Cl chondrites, so they are named afterquasi-Cl (Q-Cl ) chondrites. Unlike Cl metoorites, the Q-Cl chondrites possess chondrulestructure, and the compositions of high-temperature condensates (chondrule fragments, mineral grains or aggregates) show that the oxygen fugacity varied within a wide range in the surroundings where they were formed, similar to the variation range from E-, H-, L-, LL- t0 C-group chondrites. It is inferred that the Q-Cl chondrites could be formed at the edges far fromthe equator in the whole asteroid region of the soar nebular disk, where the nebula was lowerin density and the txindensates were lower in accretion velocity, so that the hydration of chondrules and matrix occurred during the late stage of nebular condensation. The discovery of theQ-Cl chondrites and the fact that the earth and other terrestrial planets contain water indicatethat at the edges far from the erluator in the terrestrial region of the solar nebular disk, a largeamount of water was incorporated into the lattice of minerals in the condensates as a result ofhydration during nebular condensation, and then found its way into the interior parts of theEarth and other terrestrial planets due to accretion.

关 键 词：南极 陨星 宇宙化学 球粒状陨石 水合作用 星云压缩 

分 类 号：P68[天文地球—地质学]