GRV 90027 is a Martian lherzolitic shergottites （L-S） containing poikilitic, non-poikilitic, and melted pocket components. GRV 99027 is mainly composed of olive （55 vol% ） and pyroxene （37.5 vol% ）, with minor m...GRV 90027 is a Martian lherzolitic shergottites （L-S） containing poikilitic, non-poikilitic, and melted pocket components. GRV 99027 is mainly composed of olive （55 vol% ） and pyroxene （37.5 vol% ）, with minor maskelynite （6 vol% ） and chromite （ 1.5 vol% ）, and trace whitelockite and troilite, ect. In this paper, the mineralogy and petrology of GRV 99027 are reported; in addition, the geochemical characteristics of the REEs and H isotopes in the GRV 99027 are also further investigated. The 2REE in GRV 99027 is relatively low; HREEs are enriched in olivine and pyroxene grains; LREEs are enriched in plagioclase with a high positive Eu anomaly. High EREE value is found in rare mineral whitlockite （less than 0. 2 vol% ）, LREE ≈ HREE, and whitlockite has a negative Eu anomaly. The REE distribution patterns of the whole -rock of GRV 99027 is similar to but different from that of other L-S Martian meteorites, indicating that they came from different location of Mars. GRV 99027 has a high 8D value. Different water-bearing minerals give different contribution for 8D value. The 8D of phosphates generally does not correlate with water content, and 8D has a weak negative correlation with water content. GRV 99027 can be classified as an L-S Martian meteorite based on mineralogical assemblage patterns, REE distribution patterns, and hydrogen isotope. The isotope data of Sr, Nd, Pb, Os and REE from other L-S Martian meteorites were collected to discuss the formation history of the GRV 99027. Similar to other L-S Martian meteorites, GRV 99027 originated from part of Mar＇s mantle; during one strong impact event about 4M years ago, the meteorites were ejected from deep mantle into space, and traveled for a different duration in space （indicated by different cosmic exposure time）, and captured by the Earth later in different time, ultimately falling on the Antarctica as L-S Martian meteorites.展开更多
We have determined the concentrations of 10Be and 26Al in GRV 99027 recovered by the 16th Chinese Antarctic expedition team, which are 14.1 ± 0.6 dpm/kg and 67.5 ± 3.4 dpm/kg, respectively. From the concentr...We have determined the concentrations of 10Be and 26Al in GRV 99027 recovered by the 16th Chinese Antarctic expedition team, which are 14.1 ± 0.6 dpm/kg and 67.5 ± 3.4 dpm/kg, respectively. From the concentration of 10Be, we calculate a cosmic-ray exposure age of 4.4 ± 0.6 Ma for GRV 99027. The concentration of 26Al is too high compared to the 10Be exposure age, indicating extra production from solar ray. The exposure ages, petrologic and geochemical characteristics of mantle-derived Martian meteorites GRV 99027, LEW 88516, Y-793605, NWA 1950 and ALHA77005 are very similar, suggesting that these meteorites most probably were ejected from Mars in the same impact event.展开更多
文摘GRV 90027 is a Martian lherzolitic shergottites （L-S） containing poikilitic, non-poikilitic, and melted pocket components. GRV 99027 is mainly composed of olive （55 vol% ） and pyroxene （37.5 vol% ）, with minor maskelynite （6 vol% ） and chromite （ 1.5 vol% ）, and trace whitelockite and troilite, ect. In this paper, the mineralogy and petrology of GRV 99027 are reported; in addition, the geochemical characteristics of the REEs and H isotopes in the GRV 99027 are also further investigated. The 2REE in GRV 99027 is relatively low; HREEs are enriched in olivine and pyroxene grains; LREEs are enriched in plagioclase with a high positive Eu anomaly. High EREE value is found in rare mineral whitlockite （less than 0. 2 vol% ）, LREE ≈ HREE, and whitlockite has a negative Eu anomaly. The REE distribution patterns of the whole -rock of GRV 99027 is similar to but different from that of other L-S Martian meteorites, indicating that they came from different location of Mars. GRV 99027 has a high 8D value. Different water-bearing minerals give different contribution for 8D value. The 8D of phosphates generally does not correlate with water content, and 8D has a weak negative correlation with water content. GRV 99027 can be classified as an L-S Martian meteorite based on mineralogical assemblage patterns, REE distribution patterns, and hydrogen isotope. The isotope data of Sr, Nd, Pb, Os and REE from other L-S Martian meteorites were collected to discuss the formation history of the GRV 99027. Similar to other L-S Martian meteorites, GRV 99027 originated from part of Mar＇s mantle; during one strong impact event about 4M years ago, the meteorites were ejected from deep mantle into space, and traveled for a different duration in space （indicated by different cosmic exposure time）, and captured by the Earth later in different time, ultimately falling on the Antarctica as L-S Martian meteorites.
基金National Natural Science Foundation of China (Grant Nos. 40673054 and 40232026)
文摘We have determined the concentrations of 10Be and 26Al in GRV 99027 recovered by the 16th Chinese Antarctic expedition team, which are 14.1 ± 0.6 dpm/kg and 67.5 ± 3.4 dpm/kg, respectively. From the concentration of 10Be, we calculate a cosmic-ray exposure age of 4.4 ± 0.6 Ma for GRV 99027. The concentration of 26Al is too high compared to the 10Be exposure age, indicating extra production from solar ray. The exposure ages, petrologic and geochemical characteristics of mantle-derived Martian meteorites GRV 99027, LEW 88516, Y-793605, NWA 1950 and ALHA77005 are very similar, suggesting that these meteorites most probably were ejected from Mars in the same impact event.
