富钙长石-橄榄石包体与其他部分典型包体W-L边的成因

球粒陨石中的富Ca、Al包体(简称CAI)形成于星云演化的最初始阶段,保存了大量星云形成和演化的各种信息。研究认为,包体的成因主要包括星云直接凝聚和熔融结晶,少部分甚至经历过高温蒸发过程。部分CAI最外层具有由一种或几种矿物组成的Warking-Lovering边(简称为W-L边),CAI和其W-L边对于认识早期星云环境和界定CAI的形成时间等均具有重要意义。目前,对于W-L边的形成过程研究并不深入,且一直存在争议。本文主要介绍了三个典型包体:C#1(富钙长石-橄榄石包体)、GRV 022459-2RI5(A型包体)和GRV 021579-3RI5(富尖晶石球粒状包体)及其W-L边的矿物岩石学和氧同位素组成特征。C#1包体明显经历过熔融结晶过程,W-L边氧同位素组成具有与包体内部矿物相似的富~(16)O同位素特征,表明W-L边的成因与包体的形成过程密切相关,形成于同一富~(16)O同位素组成区域,且W-L边属于包体熔融结晶过程后期的产物。矿物岩石学特征表明,GRV 022459-2RI5属于星云直接凝聚形成,其W-L边为包体形成过程最晚期星云凝聚产物。GRV021579-3RI5经历过熔融结晶过程,其W-L边为包体结晶最后阶段的产物。

The formation of Warking-Lovering rim of plagioclase-olivine and else two typical Ca-, Al-rich inclusions

Ca-, Al-rich inclusions (CAIs) are the earliest assemblages of the solar nebula, and they contain information of early solar nebula. They are the probe of studying the origin and evolvement of early solar nebula. The formations of CAIs include gas-solid condensation, crystallization from melting or partial melting and high-temperature residues. Some CAIs are often surrounded by thin mono- or bi-mineral rims known as Wark-Lovering (W-L) rims. CAIs and their W-L rims offer a record of conditions during the earliest stages of Solar System formation in the inner regions of the solar accretion disk. However, the W-L rim forming processes themselves main poorly understood. In this paper, we report the petrography, mineral chemistry and oxygen isotopes characteristics of three CAIs (C#1: plagioclase-olivine inclusion; GRV 022459-2RI5: type A inclusion; GRV 021579-3RI5: spinel-rich spherule inclusion) and their W-L rim. C#1 inclusion was crystallized from melts. The oxygen isotopes of W-L rim are similar with the interior minerals, and its argue for a same ¹⁶O-rich reservoir of W-L rim and interior minerals of C#1 inclusion. The petrography and mineral chemistry argues that GRV 022459-2RI5 was likely assemblages of solar nebular condensates, and the W-L rim of the CAI was the latest assemblages of nebular condensates. GRV 021579-3RI5 was crystallized from melts, and the W-L rim of the spinel-rich spherule was the latest assemblages from the melts.