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LUNAR METEORITES: WITNESSES TO THE MOON’S COMPOSITION AND EVOLUTION Miao Bingkui，Chen Hongyi，Xia Zhipeng，Yao Jie，Xie Lanfang，Ni Wenjun，Zhang Chuantong 2013, 25 (4):  315-328.  DOI: 10.3724/SP.J.1084.2013.00315 Abstract ( 1812 )   PDF (1992KB) ( 1964 )   Lunar meteorites are the rock sample of the Moon that were experienced the shock event by asteroids and splashed away from it. Since the first lunar meteorites (ALHA 81005) was discovered and identified in 1979, there is the collection of 136 lunar meteorites. The Apollo and Luna projects returned 382 kg lunar samples, because the collection sites are very limited, so lunar meteorites are still the important supplementary to get insight of the composition and evolution history of the Moon. Except for the small amount of unbrecciated crystalline rocks, the majority of lunar meteorites are breccias which consist mainly of high land anorthositic breccias, mare basaltic breccias and the mingled breccias. According to petrographic analyses, especially clasts, lunar meteorites contain the variety of clasts as anorthosites, basalts, gabbros, troctolites, norites and KREEP rocks. There are more and more KREEP components found in lunar meteorites, in which the VHK KREEP clasts in SaU 169 may represent the urKREEP magma, and these KREEP components will provide the important information of the KREEP origin. Some works indicate that there are 6 launching pairs identified and 9 possible launching sites from the Moon. And the discovery of the lunar symplectites has the significance of the shock metamorphism on the lunar surface. Furthermore, the isotopic ages and the composition of noble gases not only provide the important information of the processions of crystallization of lunar rocks and the formation of lunar crust, but also get insight of the history of shock events on the lunar surface. Related Articles | Metrics

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PETROLOGICAL AND MINERALOGICAL CHARACTERISTICA OF LUNAR METEORITE MIL 090070 FROM ANTARCTICA Yao Jie，Miao Bingkui，Chen Hongyi，Xie Lanfang，Xia Zhipeng 2013, 25 (4):  329-341.  DOI: 10.3724/SP.J.1084.2013.00329 Abstract ( 1488 )   PDF (8416KB) ( 972 )   MIL 090070 is a new lunar meteorite that found in 2009, it’s a lunar highland anorthosite. It has a typical breccias texture which consists mainly of lithic clasts, mineral clasts, glassy clasts and fine-grained matrix. Its lithic clasts include anorthositic polymict clast anorthosite clast, gabbro clast, gabbroic norite clast, gabbroic troctolite clast, gabbroic anorthosite clast and olivine-gabbro clast. And there are mineral clasts of augite, pigeonite, plagioclase, spinel, quartz and ilmenite et al. The glassy clasts are anorthositic, its shapes usually are thin plate-like and bending plate-like and there are a lot of fractures in them. The mineral assemblage is plagioclase (86vol%，An92—99), olivine（6vol%，Fo53—89）, pyroxene（7vol%，En25—83Fs7—43Wo2—45）, spinel, ilmenite and silica et al. In addition, the pyroxene has two kinds of augite（En25—63Fs7—43Wo6—45）and pigeonit（En55—83 Fs13—41Wo2—5）. The Mn to Fe values of olivine and pyroxene plot mostly in the area of the moon-origin rocks which are far from those of the earth, the mars, the venus and the asteroid. MIL090070 experienced many shock events and cemented by the shock-induced glassy breccias. Then the mineral composition and grain size of the lithic clasts changed gradually and the lithic clast types became more varied and complicate during the shock events. The study on petrology of MIL 090070 including clast types and texture features will help to get insight of the process of formation of the lunar regolith. Related Articles | Metrics

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PETROGRAPHY AND MINERALOGY OF A NEW LUNAR METEORITE MIL090036 Xie Lanfang，Miao Bingkui，Chen Hongyi，Xia Zhipeng，Yao Jie 2013, 25 (4):  342-351.  DOI: 10.3724/SP.J.1084.2013.00342 Abstract ( 1636 )   PDF (5386KB) ( 1437 )   　　　MIL090036 is a newly found meteorite. Belong to feldspathic polymict lunar meteorite. Here we report the detailed petrography and mineralogy of this meteorite. The breccia of MIL090036 are abandunce in quantity and type. In the MIL090036 we found primary lithic clasts (anorthosite, gabbroic anorthosite, gabbro, regolith breccia, troctolite, microporphyritic crystalline impact melt breccia). Anorthositic and quartziferous melt clasts were also observed. Major mineral fragments include pyroxenes, plagioclase, small number of olivine and ilmenite .The composition of the matrix including melt glass, fine-grained crystalline mineral and fragment of mineral (plagioclase, pyroxene, ilminite, olivine, quartz). plagioclase grains in gabbro and anorthosite are relatively poored in Ca（An81-83, An88-93）than those in other breccia (An90-98). Pyroxene grains in lithic clasts , mineral fragments and anorthositic melt clasts are relatively poored in Fe（Fs 12-35Wo3-44 En22-79）, and those in quartziferous melt clasts , matrix are relatively enriched in Fe（Fs 37-65Wo10-29 En21-49 , Fs18-69Wo3-45 En14-50）. Where pyroxene grains in gabbroic anorthosite show a narrow compositional range（Fs 24-27Wo7-14 En59-69）. Olivine grains in mineral fragments and matrix show a wide compositional range（Fo57-79） than those in lithic clasts(Fo67-77). Fe/Mn molar ratios in olivine range from 47 to 83 with an average of 76 , and those in pyroxene vary from 76 to 112, consistend with the lunar olivine and pyroxene trend . MIL090036 is similar petrographicaiiy and geochemically to samples from Apollo16 . MIL090036thus enhances our understanding of the mineral and chemical compositions of the lunar surface. Related Articles | Metrics

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THE PETROLOGY AND MINERALOGY OF LUNAR METEORITE EET 96008 FROM ANTARCTICA Xia Zhipeng，Miao Bingkui，Chen Hongyi，Yao Jie，Xie Lanfang 2013, 25 (4):  352-361.  DOI: 10.3724/SP.J.1084.2013.00352 Abstract ( 1682 )   PDF (7330KB) ( 970 )   The EET 96008 is a lunar basaltic breccia collected from the Elephant Moraine region of Antarctica. The petrography and mineralogy of EET 96008 is described in detail. The meteorite has a typical breccias texture which consists of sub-angular clasts of clasts (50.2vol%) and matrix(49.8vol）, the clasts have the size of 0.1-2mm generally. The meteorite clast types are divided into three main categories: mineral clasts, rock clasts and glassy clasts: (1) Mineral clasts include pyroxene, olivine, feldspar and quartz. (2) And rock clasts are mainly granulite, basic rock and noritic anorthosite. (3) Glassy clasts are anorthositic. In grain size, the clasts and matrix vary gradually, the matrix consists of mineral clasts and glassy clasts which are only in smaller size than 0.1 mm. The meteorite has a variety of pyroxene. The pyroxene compositions cover almost over the entire pyroxene quadrilateral (Fs17.95-58; Wo3.95-45.17; En3.45-79.07). It also possesses extensive exsolution lamellae which are up to 1μm in width. Fe content in the olivine is relatively high, which can be mainly divided into two areas：Fa50-70 and Fa80-95, the average Fa is 71.8. The component of plagioclase in the EET 96008 is enriched in Ca. Some plagioclases have been converted into maskelynite. EET 96008 is the same lunar basaltic breccia as the QUE 94281, they share the similar texture and mineral assemblage. Their clear differences in clast type and mineral composition of olivine indicate that they are not paired and may came from the different source. EET 96008 has the three typical shock-induced darken areas, and a great deal of glassy clasts and shock pockets, suggesting that its shock stage should be above S5. The study on phenomenon that ferrosilite decomposes into hedenbergite - fayalite - quartz in the meteorite will provide the insight for the shock history of the lunar surface. Related Articles | Metrics

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COMPARATIVE STUDY OF MAGNETIC SUSCEPTIBILITY AND CHEMICAL CLASSIFICATION SCHEMES OF ORDINARY CHONDRITES RECOVERED FROM THE GROVE MOUNTAINS Hu Sen，Lin Yangting，Feng Lu，Luo Hongbo，Liu Tao，Miao Bingkui 2013, 25 (4):  362-368.  DOI: 10.3724/SP.J.1084.2013.00362 Abstract ( 1727 )   PDF (3148KB) ( 1328 )   China has recovered 11452 meteorites from Grove Mountains of Antarctica after 5 explorations. It is a tough work to determine the chemical groups and petrography types. Traditional chemical classification of meteorites is destructive and needs a lot of time to prepare the sections, but also needs a mount of financial funds and human work to finish the fundamental classifications. So some researchers attempt to establish the magnetic susceptibility classification of meteorites, which is un-destructive and efficient. About 2300 ordinary chondrites recovered from Grove Mountain, Antarctica, have been classified under the organization of resource-sharing platform of polar samples and funded by Ministry of Science and Technology of the People’s Republic of China during 2003-2008. This paper will comparatively study the magnetic susceptibility and chemical classifications of the upper meteorites and assess its application in the future. References | Related Articles | Metrics

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PETROGRAPHY, MINERAL CHEMISTRY AND CLASSIFICATION OF SOME GROVE MOUNTAINS METEORITES 2013, 25 (4):  369-377.  DOI: 10.3724/SP.J.1084.2013.00369 Abstract ( 1706 )   PDF (5901KB) ( 1349 )   The study of 99 meteorites which collected from the Grove Mountains, Antarctica, indicates these meteorites belong to ordinary chondrites H group, L group, LL group, Ureilite and carbonaceous chondrite, respectively. Among these meteorites, 97 are ordinary chondrites, including 1 H3, 23 H4, 9 H5, 8 H6, 2 L4, 21 L5, 31 L6, 1 LL4 and 1 LL6. Other two meteorites are olivine-pigeonite ureilite (GRV 022888) and CV3 carbonaceous chondrite (GRV 023159). Some of these meteorites experienced high degree shock, and 16 members were heavily shocked samples (15 S4 and 1 S5). These heavily shocked meteorites are favorable samples for the study of early shock history of asteroids. Weathering degree of these meteorites is slight, and shock effects are showed in all the types but the S6. These meteorites experienced only weak weathering. Key words Grove Mountains, Antarctic meteorite, ordinary chondrite, CV3, Ureilite. References | Related Articles | Metrics

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THE STUDY OF AND EXPECTATIONS FOR FINDING CARBONACEOUS CHONDRITES IN THE GROVE MOUNTAINS, ANTARCTICA DAI Deqiu，CHEN Xinyue，Yang Rongfeng 2013, 25 (4):  378-385.  DOI: 10.3724/SP.J.1084.2013.00378 Abstract ( 1587 )   PDF (2198KB) ( 1252 )   Petrography and mineral chemistry of 3 carbonaceous chondrites (GRV 020025, 021579 and 022459) collected from the Grove Mountains (GRV), Antarctica, were reported here. All 3 chondrites are unequilibrated.The modal abundance ratio of matrix/chondrule are 2.8 (GRV 020025), 1.2 (GRV 021579) and 1 (GRV 022459). GRV 022459 has the largest chondrules (0.6-2.0 mm). A total 27 Ca-, Al-rich inclusions have been found in the three chondrites. Except for one spinel-spherule in each GRV 020025 and 021579, all other inclusions can be classified as Type A (or Type A-like) or spinel-pyroxene-rich inclusions. Most of the inclusions are intensively altered, with abundant phyllosilicates in the inclusions from GRV 020025 and FeO-enrichment of spinel in GRV 022459. At last, we look forward to the step studying work of Antarctica carbonaceous chondrites. References | Related Articles | Metrics

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CHEMICAL AND PETROLOGIC STUDY OF THE HEYETANG METEORITE Shen Wenjie，Hu Sen，Lin Yangting，Miao Bingkui 2013, 25 (4):  386-393.  DOI: 10.3724/SP.J.1084.2013.00386 Abstract ( 1539 )   PDF (4441KB) ( 1254 )   Heyetang meteorite is an ordinary chondrite falling in 1998.. Petrologic subtype of Heyetang meteorite was determined on the basis of detailed petrologic and mineralogical characteristics. The mean value of Fa in olivine is 23.2 with the range from 0.6 to 48.8(percent mean deviation (PMD) = 60.1%). The mean value of Fs in low-Ca pyroxene is 9.1 with the range from 0.6 to 49.0(PMD = 97.5%). Thus, it is an unequilibrated 3 type ordinary chondrite(OC). The chemical group was indicated by Fa value, total content of Fe-Ni metal and troilite, Co and Ni contents in kamacite and it actually has L group features. According to PMD of Fa content in olivine, Cr2O3 content in olivine and Ni-rich metals in chondrules, petrologic subtype of Heyetang meteorite belongs to L3.3 type OC. And it is one of the most primitive chondrite in the non-Antarctic meteorites in China. References | Related Articles | Metrics

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PETROLOGIC CHARACTERISTICS AND CLASSIFICATION OF THE XINING METEORITE Chen Hongyi，Miao Bingkui，Liu Xijun，Xie Lanfang，Xia Zhipeng，Chen Lifei 2013, 25 (4):  394-402.  DOI: 10.3724/SP.J.1084.2013.00394 Abstract ( 1570 )   PDF (3989KB) ( 1221 )   Xining meteorite has a typically chondritic texture. The matrix displays a moderate to high degree of recrystallization, most plagioclase grains are around 5-40μm and a few grains greater than 50μm in diameter . Chemical compositions of olivine and low-Ca pyroxene in Xining meteorite are homogeneous: eg. olivine (Fa 24.7-25.2，avg. Fa 24.9, PMD 0.64%); low-Ca pyroxene ( Fs 21.3-21.9, avg. Fs 21.5, PMD 0.84%; En 77.6-78.2, avg. En 78.6; Wo 0.46-0.57, avg. Wo 0.46). This feature indicates that olivine and low-Ca pyroxene in Xining meteorite are in thermodynamic equilibrium and Xining meteorite should belong to an equilibrated ordinary chondrite. Based on the textural characteristics，metal abundance, chemical composition of silicate minerals and thermal metamorphic characteristics(the equilibrium temperature is 778℃), Xining meteorite is a L5 ordinary chondrite and beginning to change a L6. The degrees of shock metamorphism and terrestrial weathering are S3 and W0, respectively. The parent body of Xining meteorite had suffered impact and thermal metamorphism, which had resulted in fragmentation of chondrules, devitrification of glass, and recrystallization of matrix. References | Related Articles | Metrics

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GEOCHEMISTRY OF SILICATES IN THE DONG UJIMQIN QI MESOSIDERITE AND THE IMPLICATIONS FOR ITS ORIGIN Nie Xike，Kong Ping 2013, 25 (4):  403-413.  DOI: 10.3724/SP.J.1084.2013.00403 Abstract ( 1537 )   PDF (5388KB) ( 1256 )   The Dong Ujimqin Qi meteorite is a rare mesosiderite falling in Inner Mongolia, China in 1995. It consists of intimately mixed metal–sulfide and silicates. Silicates in the mesosiderite are composed of clasts (mainly olivine clasts and gabbro clasts) and gabbroic matrix. Petrographic and REE characteristics and major element compositions show that olivine clasts, matrix olivine and gabbroic rocks (including gabbro clasts and gabbroic matrix) may have crystallized from different magmas. Olivine clasts, with high contents of Mg, may be derived from the dunite mantle of a differentiated asteroid, whereas matrix olivine and gabbroic rocks may be from the same parental asteroid, i.e. the Vesta asteroid. An impact event led to mixture of materials from these two asteroids. During the bombardment, temperature rose to 1200—1450℃. Target basaltic and gabbroic rocks from the Vesta melted at the high temperature. Gabbroic rocks in the Dong Ujimqin Qi mesosiderite crystallized from the mixed melt. Olivine (both olivine clasts and matrix olivine), however, did not melt because the temperature was below their melting points. This model explains the disequilibrium between olivine clasts, matrix olivine and gabbroic rocks. Related Articles | Metrics

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SEVERAL IMPORTANT FACTORS CONCERNING THE CHEMICAL SEPARATION OF RE-OS ISOTOPES IN METEORITES Jiang Xiaoying，Wang Guiqin，Peng Li 2013, 25 (4):  414-424.  DOI: 10.3724/SP.J.1084.2013.00414 Abstract ( 1589 )   PDF (2030KB) ( 1306 )   Some important conditions are discussed in this paper for high-precision measurement of Re and Os in meteorites by means of isotope dilution technique. We have measured the Re-Os system for samples of whole rock from six ordinary chondrites and two Iron meteorites. The result shows that 1M HCl can be fit for removing rust of metal surface. And the high digestion-temperature are necessary for digestion of meteorites. The normal condition can be dissolved out only about 30% of meteorite samples Os. However, microdistillation is not very necessary after Re-Os separation by means of distillation technique but this secondary purification can improve the stability and accuracy of the signal. In contrast with samples dissolved by HNO3, the intensity of Os in samples dissolved by reverse aqua regia is far stronger. When the concentration and quantity of spikes are proper and there is a perfect equilibrium between samples and spikes, we can attain good data generally consistent with the references’. The minimum quantity of ordinary chondrites is 0.1~0.3g or the absolute abundance of Os is 100ng during digestion with low blank levels (Re 4~77pg, Os 0.5pg ~2ng) when the standard deviation of 187Os/188Os can be limited to ±4ppm(n=120, 2se). References | Related Articles | Metrics

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THE PROSPECT OF HIGH-PRECISION THERMAL IONIZATION MASS SPECTROMETRY(TIMS) APPLICATIONS IN ANTARCTIC METEORITES Peng Li，Wang Guiqin，Jiang Xiaoying，Lai Yongwang 2013, 25 (4):  425-435.  DOI: 10.3724/SP.J.1084.2013.00425 Abstract ( 1578 )   PDF (2021KB) ( 1394 )   The thermal ionization mass spectrometry (TIMS) is one of the most important techniques for isotopic measurements. TIMS technology has a broad prospect of application in cosmochemistry because of the high accuracy and sensitivityse. TRITON TIMS can mesure high–precision isotopic compositions of Re–Os、Cr、Sr、Nd and Pb systematics of meteorites. Small loads (10pg–100 ng Sr) of international standard NBS 987 were analyzed for 87Sr/86Sr isotope ratios with an precision of 5‰ to 5ppm by TIMS. The ratios of 143Nd/144Nd of LaJolla-Nd is 0.511842±0.000005 (2SE, n=28) in our lab, and the best precision is better than 2ppm. Using 207Pb–204Pb double spike, the reproducibilities of 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb can be better than ±0.0034, ±0.0046 and ±0.0100 (n=28, 2SD) for content of 5–20ng Pb samples respectively. 187Os/188Os isotopic ratios are determined under negative thermal ions mode with the precision of better than 0.2‰ for approximately tens of pg, and 20ppm for ~ng. In addition, Cr isotopes can also be measured by TIMS technique in the static multicollection mode, the precision of 50Cr/52Cr, 53Cr/52Cr, 54Cr/52Cr ratios attain to 1ppm, 2ppm and 2ppm respectively. These methods include different isotope systematics relate to lithophile and siderophile elements, long-lived radionuclides and the short-lived extinct radionuclides. And they will provide support for further study on Antarctic meteorites. References | Related Articles | Metrics

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THE RESEARCH OF CHONDRULES TYPES OF KUMTAG 004 CHONDRITE FROM XINJIANG AND THE APPLICATION OF CHONDRULES CLASSIFICATION SCHEMES Zhang Chuantong，Miao Bingkui，He Huaiyu 2013, 25 (4):  436-448.  DOI: 10.3724/SP.J.1084.2013.00436 Abstract ( 1548 )   PDF (5695KB) ( 1173 )   Chondrules are the main constituents of chondrites. There are 3 main kinds of classification schemes of chondrules currently, i.e., texture, FeO-SiO2 and M-FeO-CaO. The texture classification depends on texture and morphology highly but chemical composition unclosely. The FeO-SiO2 and M-FeO-CaO classification schemes introduce mineral chemical criteria onto traditional texture taxonomic scheme and can further insight into the physical-chemical process occurring in the solar nebula. But the practical applications are too few for the latter two schemes. The chondrules in Kumtag 004 (L4, S4, W3) which from the new desert meteorites enrichment region-Kumtag desert of Xinjiang have been classified base on the three classification schemes after observing structure and analyzing composition. Then we discuss the merit and demerit of the FeO-SiO2 and M-FeO-CaO classification schemes and the application range. For the FeO-SiO2 taxonomic scheme that can apply to porphyritic chondrules as well as non-porhyritic chondrules, wo suggest that FeO=7.5% (wt%) is the boundary between type I and II chondrules and so are 47% and 53%(SiO2, wt%) for type A, AB and B chondrules. A approximate partition is proposed for the type A1（FeO＜1，CaO＞1）, A2（FeO≈1-3，CaO＜0.5）, A5（FeO≈11-14，CaO≈0.3-0.9） and B（FeO＞3，CaO＜0.5） chondrules for the M-FeO-CaO classification scheme based on the pyroxene (FeO and CaO, wt%). Related Articles | Metrics