陨石学及天体化学研究某些新进展

Some Recent Advances in Meteoritics and Cosmochemistry

陨石是来自含气体-尘粒的太阳早期星云盘凝聚和吸积的原始物质,大多数原始物质因吸积后的作用过程而改变(如月球、地球及火星样品),但有一些却完整的保存下来(如球粒陨石或球粒陨石中的难熔包体)。这些原始的物质通常依据同位素丰度特征来识别,依据其矿物-岩石学特征和成因可将已知的陨石划分许多更小的类型。陨石学及天体化学的新近进展包括:新近识别的陨石群;发现新类型球粒陨石及行星际尘粒中发现前太阳和星云组分;利用短寿命放射性核素完善了早期太阳系年代学;洞察宇宙化学丰度、分馏作用及星云源区及通过次生母体的作用过程阐释星云和前星云的记录。本文概述了早期太阳系内从星云到陨石的演化过程。依据这些资料,对早期太阳系所经历的多种核合成的输入、瞬时加热事件与星云动力学有一些新的认识,以及认识到小星子和行星体系的演化比以前预期的更快速。

Meteorites usually derive from primitive materials that condensed and accreted from the gas-and dust-containing presolar disk.Most of them were altered by postaccretionary processes（as in lunar,terrestrial,and martian samples）,but some survived essentially integrity（as chondrites or inclusions in chondrites）.These primitive chondrites are recognizable usually from isotopic abundance characteristics.Based on mineral-petrologic characteristics and their origin we can classify known meteorites into a much smaller number of types.Recent advance in miteoritic and cosmochemistry include the newly recognized meteorite groups;discoveries about the presolar and nebular components of chondrites and interplanetary;improvements in early solar system chronology using short-radionuclides;new insights into cosmochemical abundances;fractionation,and nebular reservoirs;and advance explanation for nebular and prenebular records of secondary parent body processes.We summarized evolved process from nebula to meteorite in early solar system.Some new insights based on these data are that the early solar system experienced a variety of nucleosynthetic input,the dynamic entity with transient heating events,and the system of plantesimals and planets evolved more rapidly than previously expected.