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30 June 1959, Volume 20 Issue 2-English Previous Issue    Next Issue
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Progress in study of Chinese AntarcticMeteorites Lin Yangting, Wang Daode, Ouyang Ziyuan 2009, 20 (2-English):  81-96.  Abstract ( 1080 )   PDF (1877KB) ( 923 )   This paper reviews and summarizes the Chinese Antarctica meteorite search, classification and research. During the past four antarctic explorations, a total of 9834 meteorites were collected in the Grove Mountains region. Among them, 2431 meteorites were classified by the end of 2008. So far, 684 meteorites have been officially published in the Meteoritical Bulletin, Meteoritical Society, including 2 martian meteorites, 2 eucrites, 6 ureilites, 5 mesosiderites, 1 pallasite, 1 iron and 10 carbonaceous chondrites. Comprehensive studies were carried out on a number of these rare typemeteorites. In addition, we propose to continue themeteorite searching project in Grove Mountains and other regions in Antarctica. We also suggest several key topics of the future researches on the Chinese Antarctic meteorites. Related Articles | Metrics

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Classification of Grove Mountains meteorites and its significance Miao Bingkui, Wang Daode 2009, 20 (2-English):  97-109.  Abstract ( 1223 )   PDF (695KB) ( 827 )   Meteorites are the extraterrestrial rocks, which provide insights into the origin and evolution of the solar system. During the past half century, a great number of meteorites has been discovered on the Antarctic Ice Sheet, confirming that the Antarctica is the most important meteorite concentration area on the earth. Since the first four Antarctic meteorites were found in Grove Mountains in 1998, a total of 9834 meteorites have been collected by four subsequent expeditions. It opens a new field of meteorite study in China, and also accumulates a great deal of scientific samples for China. Recently, classification of Grove Mountains meteorites has been carried out for 6 years, and made following progresses: (1)  2433 meteorites, which include many specialmeteor ites, e. g. M artian meteorites, ureilites and carbonaceous chondrites, have been classified. (2) the Antarctic meteorite curation and the sample sharing system are set up prelminarily. (3) the classification procedure, the manag ement of meteorite samples, and the application procedure for the Antarctic meteorites are completed after the systematic classification during these years. (4) young generation researchers on meteorite are trained through the cooperation of many universities and institutes onmeteorite classification. Related Articles | Metrics

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Geochemistry of the Martian Meteorite GRV 99027 Wang Henian, Xie Zhidong, Liang Ying 2009, 20 (2-English):  110-134.  Abstract ( 1020 )   PDF (5576KB) ( 966 )   GRV 90027 is a Martian lherzolitic shergottites ( L-S) containing poikilitic, non-poikilitic, andmelted pocket components. GRV 99027 is mainly composed of olive ( 55 vol%) and pyroxene ( 37. 5 vol% ), with minormaskelynite ( 6 vol% ) and chromite ( 1. 5 vol% ), and trace white lock ite and troilite, ec.t 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 REE in GRV 99027 is re latively low; HREEs are enriched in olivine and pyroxene grains; LREEs are enriched in plagioclase w ith a high positive Eu anomaly. High REE value is found in rare minera l whitlockite ( less than 0. 2 vol% ), LREE-HREE, and whitlock ite has a negative Eu anomaly. The REE distribution patterns of the whole rock of GRV 99027 is smiilar to but different from that of other LSM artian meteorites, indicating that they came from different location of Mars. GRV 99027 has a high δD value. Different water-bearing minerals give different contribution for δD value. The δD of phosphates generally does not correlate with water content and δD has a weak negative correlation with water content. GRV 99027 can be classified as an L-SM artian meteor ite based on mineralogical assemblage patterns, REE distribution patterns, and hydrogen isotope. The isotope data of Sr, Nd, Pb, Os and REE from other L-SM artianmeteorites were collected to discuss the formation history of the GRV 99027. Simillar to other L-S M artian meteorites, GRV 99027 or iginated from part of Mar' smantle; during one strong mipact event about 4M years ago, the meteorites were ejected from deep mantle into space, and trave led for a different duration in space ( indicated by different cosmic exposure time), and captured by the Earth later in different time, ultmiately falling on the Antarctica as L-SM artianmeteorites. Related Articles | Metrics

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Subdivision of petrologic type of unequilibrated ordinary chondrites from Antarctica Jiang Yun, Hsu Weibiao 2009, 20 (2-English):  135-150.  Abstract ( 1300 )   PDF (5632KB) ( 833 )   We report results of petrologic and mineralogical studies of 25 unequilibrated ordinary chondrites (19 Chinese Antarctic meteorites) using electron microprobe, scanning electron microscopy ( SEM ) and energy-d is persive X-ray spectrometry ( EDS) techniques. With increasing degree of thermalmetamorphism, chemical zoning of olivine was erased; plessite was transformed into intergrowths of coarser-grained kamacite and Ni-richmetal; Cr exsolved from ferroan olivine, produced needle-like crystals and coarsened into equant chromite grains; and feldspar crystallized during devitrification of glass and recrystallization of matrix. These features can help to identify different metamorphic grades. Based on the scheme by Sears et al (1982), we subdivided type 3 Chinese Antarctic ordinary chondrites into petrologic type 3.3 to 4 ( 3 type 3. 3, 3 type 3. 4, 1 type 3. 5, 2 type 3. 6, 2 type 3. 7, 5 type 3. 8, 3 type 4). This classification scheme is a quite effective way to subdivide Antarctic meteorites. Additionally, we propose to revise the chemical groups of GRV 020032 and GRV 020104 to L and H, respectively. Related Articles | Metrics

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Petrography and mineral chemistry of 4 carbonaceous chondrites from the Grove Mountains, Antarctica Dai Deqiu, Wang Daode 2009, 20 (2-English):  166-171.  Abstract ( 1041 )   PDF (1593KB) ( 1583 )   Petrography and mineral chemistry of four carbonaceous chondrites ( GRV 020017, GRV 020025, GRV 021579, GRV 022459) collected from the Grove Mountains ( GRV ), Antarctica, were reported here. All four chondrites are unequilib rated, as indicated by well shaped chondrules and the chemical variations of olivine and low-Capyroxene. The modal abundance ratio of matrix/chondrule are 2 ( GRV 020017), 2. 8 ( GRV 020025), 1. 2 ( GRV 021579 ), 1 ( GRV 022459 ). GRV 022459 has the largest chondrules( 0.6-2.0mm). A total of 30 Ca-Al-rich inclusions were found in the four meteorites. Most inclusions were highly altered, with abundant phyllos ilicates in the inclusions of GRV 020017 and GRV 020025. On the base of petrography and mineral chemistry, these chondrites are classified as CM 2 ( GRV 020017 and 020025), CO 3 ( GRV 021579) and CV 3 ( GRV 022459). Related Articles | Metrics

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Shock metamorphism in meteorites Xie Zhidong 2009, 20 (2-English):  172-186.  Abstract ( 904 )   PDF (1893KB) ( 894 )   Shock metamorphism resulting from hypervelocity collisions between planetary bodies, is a fundamental processes in the solar system. The term "shock metamorphism" is used to describe all changes in rocks and minerals resulting from the passage of shock waves. Mostmeteorites have experienced collisions and have a record of shock metamorphism, which includes brecciation, deformation, phase transformation, local melting and crystallization. The key to reading this record is to use the shock features to estmiate the pressure and duration of shock event. In this paper, the history of the study of shock metamorphism is reviewed; basic knowledge of shock physics is discussed; recent 10 years' studies of shock-induced melt veins are summarized; and finally a short note to the shock metamorphism in general is given. Related Articles | Metrics

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Shock metamorphism of ordinary chondrites from Grove Mountains, Antarctica Feng Lu, Lin Yangting, Hu Sen, Liu Tao 2009, 20 (2-English):  187-199.  Abstract ( 1433 )   PDF (4664KB) ( 919 )   Shock effects of 93 Grove Mountains ( GRV ) ordinary chondrites were studied in this work, including fracture, various types of extinction, and recrystallization of silicates observed under optical microscopy. Shock-induced veins and pockets how various microtextures, decomposition and phase transformation of minerals. The on firmed high-pressure polymorphs of silicates are ringwoodite, majorite, pyroxene lass and maskelynite. Based on the shock effects and assemblages of h igh-pressure  inerals, shock stages of all of 93 GRV chondrites were classified. In comparison with literature, the Grove Mountains meteorites have a higher fraction ( 23 out of 93) if heavily shocked samples ( S4-S5). Most of the heavily shocked meteorites are L group ( 22 out of 23), except for one H chondrite. The distinct shock metamorphism between H and L groups may indicate different surface properties of their parent bodies. In add ition, there is rela tionship between petrologic types and shock stages, with most heavily shocked samples observed in equilibrated ordinary chondrites ( especially Type 5 and 6). Related Articles | Metrics

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GRV 051523: A new eucrite Liu Tao, Lin Yangting, Hu Sen, Feng Lu 2009, 20 (2-English):  200-208.  Abstract ( 891 )   PDF (3023KB) ( 878 )   Grove Mountains ( GRV) 051523 is a new ly identified eucrite, consisting mainly of coarse-grained pyroxene ( 62. 9 vol%) and plagioclase ( 34. 2 vol%), with less abundant opaquem inerals ( 2.7 vol%), minor silica and tiny FeO-rich olivine ( Fa75 ). Coarse-grained pyroxenes show exsolution of augite lamellae in pigeonite or vice versa. Width of most exsolution lamellae in pyroxenes is 1-3 μm. Opaquem inerals are mainly chromite, ilmenite and sulfides. Themeteorite was heavily shocked, as indicated by breccias andmelt veins. Coarse-grained pyroxenes commonly contain abundant tiny or needle-like chromite inclusions with orientation, probably due to heavy shock events. Pyroxenes in various petrographic occurrences exhibit highly homogeneous compositions, indicating that GRV 051523 experienced intense thermal metamorphism in the parent asteroid 4 Vesta. GRV 051523 is classified as Type 5-6. This new eucrite will have additional constraints on chemical composition, magmatic differentiation, multi-stage shock and thermal history of Vesta. Related Articles | Metrics

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The study of Mg isotope compositions of terrestrial rocks and meteorites Wang Guiqin, Lin Yangting, Wang Daode 2009, 20 (2-English):  209-214.  Abstract ( 804 )   PDF (187KB) ( 803 )   The study of Mg isotopes has been carried out for about 40 years since 1970 s. With analytical progress, the study is not only limited to the excess of 26Mg due to decay of short-lived 26Al in prinitive meteorites, also extended to mass-de-pendent fractionation of Mg isotopes in meteorites and terrestrial rocks. This paper reviews recent development in Mg isotope researches. Related Articles | Metrics

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Weathering, shock metamorphism and type distribution patterns of 98 ordinary chondrites from the Grove Mountains, Antarctica Dai Deqiu, Wang Daode, Miao Bingkui 2009, 20 (2-English):  215-224.  Abstract ( 1104 )   PDF (284KB) ( 793 )   Petrography and mineral chemistry of ninety-eight ordinary chondrites from Grove Mountains (GRV), Antarctica, were presented and their. Weathering effect, shock metamorphism and type distribution patterns were discussed in this study. Among them, six are unequilibrated ordinary chondrites, including 3 H3 and 3 L3; and 92 meteorites are equilibrated ordinary chondrites, including 24H-group (13H4, 10H5, 1H6), 64 L-group ( 2 L4, 44 L5, 18 L6) and 4 LL-group ( 3 LL4, 1 LL5). Most GRV chondrites ( > 90% ) displayed minor weathering effect (W 1 and W 2). About half of the meteorites experienced severe shockmetamorphism. They commonly contain shock-induced melt veins and pockets. These heavily shocked meteorites provide us with natural samples for study of high-pressure polymorphs of minerals. In addition, the Grove Mountains collection seems to have more abundant unequilibrated and L group ordinary chondrites compared to the US Antarctic meteorite collection which were mainly found along the Transan tarctic Mountains. Related Articles | Metrics