The terrestrial alteration of Saharan Shergottites Dar al Gani 476 and 489: A case study of weathering in a hot desert environment

被引:98
作者
Crozaz, G [1 ]
Wadhwa, M
机构
[1] Washington Univ, Space Sci Lab, St Louis, MO 63130 USA
[2] Washington Univ, Dept Earth & Planetary Sci, St Louis, MO 63130 USA
[3] Field Museum Nat Hist, Dept Geol, Chicago, IL 60605 USA
基金
美国国家科学基金会;
关键词
D O I
10.1016/S0016-7037(00)00586-X
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
Rare earth element (REE) and other selected tract and minor element concentrations were determined in various phases of Dar al Gani 476 and 489. two basaltic shergottites recently found in the Libyan Sahara. Whereas merrillite and feldspathic glass compositions do not seem to have been altered since the fall of these meteorites, olivine and pyroxenes commonly show light REE enrichments, sometimes accompanied by Ce anomalies, that are attributed to terrestrial alteration. Sr and Ba enrichments are also observed. The calcium carbonate that resides in most cracks is essentially devoid of REE but a fine-grained amorphous silicate material that fills some veins and pockets has striking light REE enrichments and elevated P, Sr. and Ba. It is argued that this material, likely to be impact melt. as well as the notoriously light REE-poor olivine acid pyroxenes, were preferentially affected by a crustal light REE-rich contaminant. Caution is urged when using whole rock, or even mineral separate, compositional, and isotopic data for hot desert meteorites, Copyright (C) 2001 Elsevier Science Ltd.
引用
收藏
页码:971 / 977
页数:7
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