TY - JOUR
T1 - Mineralogy of fine-grained rims in the ALH 81002 CM chondrite
AU - Lauretta, Dante S.
AU - Hua, Xin
AU - Buseck, P R
N1 - Funding Information:
This work was supported by NASA Grant NAG5-4308. We thank I. Dodony for sharing his knowledge of phyllosilicates and electron microscopy techniques. We also thank J. Li and T. J. Zega for helpful discussions, and K. Weiss and J. Wheatley for technical assistance. C. M. O. D. Alexander, A. Bischoff, and M. E. Zolensky provided constructive reviews. The NASA Antarctic Meteorite Working Group provided the sample of ALH 81002.
PY - 2000
Y1 - 2000
N2 - The mineralogy of fine-grained rims in ALH 81002, a relatively primitive CM carbonaceous chondrite, has been determined by using transmission electron microscopy. The most abundant phase is Mg-rich serpentine, which occurs in small (≤20 nm) crystals with cylindrical or fibrous morphologies. Cronstedtite, an Fe-rich phyllosilicate, occurs as relatively large (100 to 2500 nm), platy crystals. Some cronstedtite is coherently intergrown with tochilinite. In many cases, cronstedtite has been partially altered to serpentine. The compositions and textures of these two phases provide a mineralogical and morphologic alteration sequence that parallels the known compositional trend for CM chondrite matrix. Accessory minerals embedded within the phyllosilicates include chlorite, pentlandite, gypsum, olivine, kamacite, taenite, and chromite. Regions containing only anhydrous minerals also occur. The hydrated and anhydrous regions are in direct contact with each other, suggesting that the rims accreted material from multiple reservoirs. Copyright (C) 2000 Elsevier Science Ltd.
AB - The mineralogy of fine-grained rims in ALH 81002, a relatively primitive CM carbonaceous chondrite, has been determined by using transmission electron microscopy. The most abundant phase is Mg-rich serpentine, which occurs in small (≤20 nm) crystals with cylindrical or fibrous morphologies. Cronstedtite, an Fe-rich phyllosilicate, occurs as relatively large (100 to 2500 nm), platy crystals. Some cronstedtite is coherently intergrown with tochilinite. In many cases, cronstedtite has been partially altered to serpentine. The compositions and textures of these two phases provide a mineralogical and morphologic alteration sequence that parallels the known compositional trend for CM chondrite matrix. Accessory minerals embedded within the phyllosilicates include chlorite, pentlandite, gypsum, olivine, kamacite, taenite, and chromite. Regions containing only anhydrous minerals also occur. The hydrated and anhydrous regions are in direct contact with each other, suggesting that the rims accreted material from multiple reservoirs. Copyright (C) 2000 Elsevier Science Ltd.
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U2 - 10.1016/S0016-7037(00)00425-7
DO - 10.1016/S0016-7037(00)00425-7
M3 - Article
AN - SCOPUS:0033785169
SN - 0016-7037
VL - 64
SP - 3263
EP - 3273
JO - Geochimica et Cosmochimica Acta
JF - Geochimica et Cosmochimica Acta
IS - 19
ER -