The chemical relationship between chondrules and matrix and the chondrule matrix complementarity
The chemical relationship between chondrules and matrix and the chondrule matrix complementarity
复制标题
DOI：
10.1016/j.epsl.2010.03.008
复制
发表时间：
2010-05
影响因子：
5.3
通讯作者：
D. Hezel;H. Palme
中科院分区：
文献类型：
--
作者：
D. Hezel;H. Palme
球粒和基质是碳质方解石的两个主要组成部分。CV、CR、CO和CM陨石中球粒和基质的Mg/Si比是互补的：球粒具有超Cl-结晶Mg/Si比，基质具有亚Cl-结晶Mg/Si比。CC块体样品中的Mg/Si比值均为Cl-，表明球粒与基质之间存在化学联系。这种化学关系对球粒的形成过程和原行星盘的化学演化有重要的限制。球粒基质的互补性排除了球粒和基质的单独起源和后来的混合。Fe和Mg在球粒和基质之间的再分配或Si从球粒中稳态浸出到母体上的基质中可以排除。陨石球粒和基质都必须由同一个化学库形成。Mg/Si的互补性可能是在母体吸积之前通过从CI球粒陨石库中提取富含Mg的成分而在星云中建立的。然后，这一组成部分作为球粒的前体，留下贫镁物质，基质的母体材料。这种解释排除了所有涉及球粒和基质的单独起源的球粒形成过程，例如X风模型。CV、CR、CO和CM球粒的这种互补性的存在也表明球粒和基质的形成过程相似。
Chondrules and matrix are the two major components of carbonaceous chondrites (CC). The Mg/Si ratios of chondrules and matrices in CV, CR, CO and CM chondrites are complementary: chondrules have super CI chondritic and matrices sub CI chondritic Mg/Si ratios. Bulk samples of CC have always CI chondritic Mg/Si ratios, indicating that chondrules and matrix are chemically connected. Such a chemical relationship places important constraints on the chondrule formation process and the chemical evolution of the protoplanetary disk. The chondrule matrix complementarity excludes separate origins and later mixing of chondrules and matrix. Redistribution of Fe and Mg between chondrules and matrix or leaching of Si from chondrule mesostasis into the matrix on the parent body can be excluded. Both, chondrules and matrix must have formed from the same chemical reservoir. The Mg/Si complementarity was probably established in the nebula before parent body accretion by the extraction of a Mg-rich component from a CI chondritic reservoir. This component then served as precursor for chondrules, leaving behind Mg-depleted material, the parent material of matrix. This interpretation excludes all chondrule forming processes that involve a separate origin for chondrules and matrix, such as, for example, the X-wind model. The existence of this complementarity in CV, CR, CO and CM chondrites also suggests that chondrules and matrix are formed by similar processes.