南极陨石与沙漠陨石的对比研究

南极冰盖和热带干旱－半干旱沙漠地区均有利于陨石样品的保存。到目前为止，已在南极约２５００ｋｍ２的蓝色冰区内回收了约１５０００块陨石。在非洲撒哈拉沙漠、西澳大利亚及美国新墨西哥州沙漠地区回收了约２０００块陨石。但由于两者的气候条件和保存陨石的环境不同，它们之间存在明显差异，南极陨石居地年龄大，风化程度低，地球污染小；沙漠陨石居地年龄小，风化程度高，地球污染大。南极和沙漠陨石的主要陨石类型的频率与已知降落的陨石相似，未观察到陨石类型通量随时间的明显变化，但在南极陨石中稀少和独特陨石类型的丰度较高，按其陨石来源将其划分为小行星陨石和行星陨石。新的和独特陨石类型的研究以及月球和火星陨石的研究有利于探索和了解早期太阳星云的连续化学分馏作用及月壳和火星表面的平均化学组成及其横向变化。

COMPARISONS OF ANTARCTIC METEORITES AND DESERT METEORITES

Meteorite samples would be better preserved in Antarctic ice sheet and hot arid semi arid region. Up to date, meteorite scientists have searched only about 2500km 2 of blue ice and recovered around 15,000 meteorite specimens. More than 2000 meteorite specimens are recovered in Africa, Sahara desert, Western Australia and Roosevelt County(New Mexico and West Texas) desert regions. Differences between the Antarctic meteorites and desert meteorites have been noted since their preservation and climate conditions are different. antarctic meteorites have long terrestrial age, contamination from Earth is smalll and they show remarkable little weathering, in contrast with Antarctic meteorites, desert meteorites have short terrestrial age, contamination from Earth is serious and weathering degree is large. Major meteorite types and their frequency of Antarctic and desert meteorites are similar with modern fall meteorites. The variations of the flux of meteorite types with time are not observed, but abundances of new and unique meteorite types are higher. According to meteorite source we classified these meteorites as asteroid meteorite and planetary meteorite. The study on new and unique meteorite types are useful for understanding continuous chemical fractionation of early solar nebula and horizonal variation of lunar crust and Martian surface.