Petrology of ureilites from Grove Mountains,Antarctica:Constraints on the origins  

作　　者：缪秉魁 林杨挺 王道德 沈文杰 王葆华 胡森 刘焘 

机构地区：[1]Key Laboratory of Geological Engineering Centre of Guangxi Province [2]College of Earth Sciences,Guilin University of Technology [3]Key Laboratory of the Earth's Deep Interior,Institute of Geology and Geophysics,Chinese Academy of Sciences [4]Key Laboratory of Isotope Geochronology and Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences

出　　处：《Chinese Journal of Polar Science》2009年第2期151-165,共15页极地研究（英文版）

基　　金：supported by the National Natural Science Foundation of China(No.40473037 and 40673055);Guangxi College Talents Support Program(RC2007020)

摘　　要：Ureilites are a common group of achondrites with a high abundance of carbon. They probably have a genetic relationship with chondrites, hence provide an insight into origin and evdution of terrestrial planets. A new meteorite-rich region, Grove Mountains （ GRV）, was found by the Chinese Antarctic Research Expedition, with discovery of 9834 meteorites. Of 2433 meteorites classified, 9 ureilites have been identified. In this paper, we report petrography of 6 of these ureilites. Four ureilites contain graphite and exhibit triangle conjunction and common reduced margins of divine. GRV 052382 probably experienced heavy shock metamorphism followed by fast coding, as indicated by mosaic texture or fine-grained granular texture of olivine. GRV 022931 was highly reduced of these ureilites, with olivine as isolated grains in abundant carbonaceous matrix. All 9 ureilites are monomict, and arc classified into subtype II （with medium FeO content, Fa15-18 ） and subtype I （with high FeO content, Fa 〉 18） based on compositions of the cores of olivine. The diverse mineral compositions and petrography of these ureilites suggest that they are not paired and reveal a multi-event history of the parent body. Partial melting of the parent body produced carbon-rich magma, followed by crystallization of graphite and silicates. Later, graphite was partially inverted to diamond by shock events. Reburial of the shocked debris experienced various degree of thermal metamorphism. Finally, these rocks were excavated from the parent asteroid and ejected into Earth-cross orbit by another impact event.Ureilites are a common group of achondrites with a high abundance of carbon. They probably have a genetic relationship with chondrites, hence provide an insight into origin and evdution of terrestrial planets. A new meteorite-rich region, Grove Mountains （ GRV）, was found by the Chinese Antarctic Research Expedition, with discovery of 9834 meteorites. Of 2433 meteorites classified, 9 ureilites have been identified. In this paper, we report petrography of 6 of these ureilites. Four ureilites contain graphite and exhibit triangle conjunction and common reduced margins of divine. GRV 052382 probably experienced heavy shock metamorphism followed by fast coding, as indicated by mosaic texture or fine-grained granular texture of olivine. GRV 022931 was highly reduced of these ureilites, with olivine as isolated grains in abundant carbonaceous matrix. All 9 ureilites are monomict, and arc classified into subtype II （with medium FeO content, Fa15-18 ） and subtype I （with high FeO content, Fa 〉 18） based on compositions of the cores of olivine. The diverse mineral compositions and petrography of these ureilites suggest that they are not paired and reveal a multi-event history of the parent body. Partial melting of the parent body produced carbon-rich magma, followed by crystallization of graphite and silicates. Later, graphite was partially inverted to diamond by shock events. Reburial of the shocked debris experienced various degree of thermal metamorphism. Finally, these rocks were excavated from the parent asteroid and ejected into Earth-cross orbit by another impact event.

关 键 词：ureilites Grove Mountains ORIGIN achondrltes Antarctica. 

分 类 号：P185.83[天文地球—天文学]