Primary Nanocrystalline Anhydrous Chondrule Mesostasis: Limited Evidence of Secondary Alteration in Most CR Chondrites

Abreu, N M ; Corrigan, C M ; Keller, L P ; Hezel, D C ; Gross, J ; Crispin, K L ; Gray, J ; Wang, H ; Sabatose, A C

关键词: ANTARCTIC REGIONS;    CHONDRITES;    CHONDRULE;    CRYSTALLINITY;    IRON OXIDES;    METEORITIC COMPOSITION;    MINERALOGY;    NANOCRYSTALS;    QUARTZ;    SILICON DIOXIDE;    TRENDS;    WEATHERING;   

RP-ID  :  JSC-E-DAA-TN66394

学科分类：空间科学

美国|英语

来源: NASA Technical Reports Server

【 摘 要 】

The chondrule regions generally regarded to be most susceptible to aqueous alteration are mesostasis and Fe-Ni metal nodules. In CMs, studies of mesostasis have successfully placed contraints into their asteroidal histories. Unlike CM mesostasis, only a few studies of CR mesostasis are currently available [e.g. 1-4]. Here we study the effects aqueous alteration can have on the texture, composition, and mineralogy of CR chondrule mesostasis from 9 Antarctic CR chondrites: EET 92062,5, EET 96259,13, GRA 95229,77, GRO 95577,61 LAP 02342,44, LAP 04516,4, LAP 04720,16 and MIL 07525,7 and MIL 090001,2, generously provided by the U.S. Antarctic Meteorite Collection. To our knowledge, this is the first detailed TEM and compositional study of differences between chondrule setting in CR mesostasis. Based on these data, we place constraints on the degree to which these CRs record aqueous alteration.