Absence of matrix-like chondrule rims in CR2 LAP 02342

作者：Wasson John T^*; Rubin Alan E

来源：Meteoritics & Planetary Science, 2014, 49(2): 245-260.

DOI：10.1111/maps.12237

In numerous past papers, it was concluded that the fine (<1m) matrix immediately adjacent to, and radially symmetric around, chondrules in primitive chondrites consists of compact (low-porosity) rims that were attached in the solar nebula. We present here textural and compositional evidence that no matrix-like (or accretionary) rims around chondrules are present in the well-preserved CR2 chondrite LAP 02342. Fine-grained matrix-rich regions (i.e., candidate rims) at the edges of chondrules were studied with an electron-microprobe-based matrix-grid technique; comparison of the rims data for matrix regions near these chondrules showed the candidate rims to be compositionally heterogeneous, inconsistent with origins as radially symmetric, matrix-like rims formed by gradual accretion. This evidence (together with simulations and laboratory studies indicating that accretionary processes produced highly porous aggregates) strongly suggests that nebular processes did not produce compact matrix-like rims around chondrules in any chondrite group.

• 出版日期2014-2