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30 December 2002, Volume 14 Issue 4 Previous Issue    Next Issue
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GROVE MOUNTAINS: A NEW FOUND METEORITES CONCENTRATION AREA 2002, 14 (4):  243-247.  Abstract ( 1594 )   PDF (348KB) ( 1049 )   Chinese National Antarctic Research Expedition ( CHINARE) has recovered 32 meteorite specimens in the Grove Mountains, East Antarctica, from 1998 to 2000. According to the location characteristics and the diversity of their classification, we conclude that the Grove Mountains is another new meteorites concentration area in the Antarctica, but needing more information to better understand its concentration mechanisms. Related Articles | Metrics

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METEORITES COLLECTION IN THE GROVE MOUNTAINS: RETROSPECT AND PROSPECT 2002, 14 (4):  248-251.  Abstract ( 1602 )   PDF (315KB) ( 1316 )   In this paper, we present some aspects of meteorites collection in the Grove Mountains, East Antarctica, by the 15th and 16th Chinese National Antarctic Research Expedition (CHIN-ARE) , from 1998 to 2000. A total of 32 samples were retrieved. Of the newly found meteorites, there is a martian lherzolite. The coming 19th CHINARE are expecting much more gifts from the blue ice. Related Articles | Metrics

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null 2002, 14 (4):  252-265.  Abstract ( 1523 )   PDF (366KB) ( 1848 )   Up to date,32 meteorites were collected on the blue ice in Grove Mountains region, Act-arctica, by 15th and 16th teams of Chinese Antarctic Expedition during 1998-1999 and 1999-2000 field seasons. Of the 32 Grove Mountains meteorites, there are 1 Iherzolitic sherg-ottite, 1 eucrite, 1 ungrouped iron meteorite and 29 ordinary chondrites. Six out of the 29 ordinary chondrites are unequilibrated L3 chondrites. Hence, Grove Mountains meteorites are characteristic of unusually high abundance of rare meteorite types. Based on review of classification and the chemical group-petrographic type distribution patterns of meteorites collected in other regions of Antarctica, we conducted a preliminary comparative study of the Grove Mountains meteorites with other Chinese meteorites. Several important issues are discussed in the paper, including meteorite concentrated areas, new meteorite type candidates, relationship between properties of meteorites with their heliocentric distance, and continuous chemical fractionation of early solar nebula. References | Related Articles | Metrics

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null 2002, 14 (4):  266-275.  Abstract ( 1491 )   PDF (561KB) ( 1492 )   null Related Articles | Metrics

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PETROLOGY OF GROVE MOUNTAINS METEORITES 1:L3 ORDINARY CHONDRITES 2002, 14 (4):  276-287.  Abstract ( 1931 )   PDF (1615KB) ( 1338 )   Six of a total of 28 meteorites collected by the 16th CHINARE from Grove Mountains, Antarctica, were classified as L3, and they show highly primitive petrography and mineralogy. In these unequilibrated chondrite, chondrules are very sharp-outlined; fine-grained matrix is almost opaque with few recrystallized grains; olivine and low-Ca pyroxene are commonly zoned, and have wide ranges of composition. Abundance of metallic Fe-Ni, calculated total Fe concentration, and mean Fa content of olivine are within the ranges of L group. Based on Percent Mean Deviation ( PMD) of Fa content of olivine, and its correction with petrographic subtype of unequilibrated ordinary chondrites( Sears et al. , 1982) , these 6 L3 chondrites are subdivided into as following; GRV 99022, 13.0-3.4; GRV 99001, L3.4; GRV 99020, GRV 99021 and GRV 99026, L3.5; GRV 99019, L3.6. Related Articles | Metrics

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PETROLOGY OF GROVE MOUNTAINS METEORITES II :EQUILIBRATED ORDINARY CHONDRITES 2002, 14 (4):  288-299.  Abstract ( 1807 )   PDF (1662KB) ( 1197 )   Of a total of 28 meteorites collected in Grove Mountains, Antarctica, by the 16th CHIN-ARE, there are 20 equilibrated ordinary chondrites. The others include 1 martian meteorite, 1 HED meteorite and 6 L3 ordinary chondrites. These 20 equilibrated ordinary chondrites are classified into chemical groups of H, L and LL, respectively, based on mean Fa content of oli-vine, mean Fs of low - Ca pyroxene and abundance of Fe-Ni metal. Their petrographic types of 4 to 6 are assigned according to structures of chondrules, degree of recrystallization of matrix and homogeneity of composition of major phases. Classification of these 20 equilibrated ordinary chondrites are as following; 6 meteorites of H group (3 H4, 1 H5 and 2 H6) , 9 of L group (3 L4, 1 L5 and 5 L6) and 5 of LL group (2 LL4 and 3 LL5). References | Related Articles | Metrics

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ANTARCTIC GRV 99027 METEORITE: A NEW MEMBER IN MARTIAN METEORITE 2002, 14 (4):  300-307.  Abstract ( 1575 )   PDF (649KB) ( 1746 )   GRV 99027 meteorite from Blue Ice Area in Antarctica is an achondrite. It consists predominantly of olivine and pyroxene. Both cumulate texture and poikilitic texture can be seen in this achondrite. These textures are peculiar to fractional crystallization of magma. The modal mineralogical composition and chemical compositions for GRV 99027 meteorite are similar to those of SNC meteorites and especially approach to ALHA 77005 meteorite. The latter has been ascertained to be a Martain meteorite of Lherozolitic-Shergotty type ( L-S type). Its mineral chemical chracteristics and FeO/MnO ratio are also similar to those of L-S type. Based on above - mentioned the authors consider that GRV 99027 meteorite is tentatively a new member of SNC meteorite clan. It is reported that SNC meteorites may be from the Mars. Due to Lherozolites correspond to composition of the mantle in the Earth, the GRV 99027 meteorite could originally occur in the depths of the Mars. Therefore, the new achondrite provides a rare sample from other planetary in the solar system and has an important significance in study on the Mars. The sample we got is very small that the research work for the achondrite is preliminary merely. To draw final conclusion ascertained GRV99027 to be a Martain meteorite many work ( such as oxygen and inert gas composition analysis, radiometric isotopic age determination and some others) should be done. Related Articles | Metrics

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CHEMICAL GROUPS AND PETROLOGIC TYPES OF 23 ORDINARY CHONDRITES FROM GROVE MOUNTAINS, ANTARCTICA 2002, 14 (4):  308-319.  Abstract ( 1318 )   PDF (678KB) ( 1315 )   Twenty-three meteorites collected from Blue Ice Area, Grove Mountains, Antarctica have been studied systematically. Observations by laser confocal microscope and determinations by electron probe revealed that neither carbonaceous chondrite nor enstatite chondrite were found among these meteorites. All 23 meteorites studied belong to ordinary chondrites. With the help of energy dispersive X-ray spectrometer installed in SEM large area chemical analytical data of the 23 chondrites were obtained from sections of these samples. According to SiO2 , ∑FeO, MgO and CaO content distribution in the histograms, chemical groups of the 23 chondrites were tentatively divided. On the basis of distribution of olivines and pyroxenes determined by electron probe in the Fa - Fs plot chemical groups of the 23 chondrites were divided, too. The two results for the 23 chondrites are almost identical. Petrologic types for the 23 chondrites are ascertained mainly based on the property of chon-drules and matrix structures of the chondrites, as well as the composition of olivines, structures of pyroxenes and characteristics of feldspars, and so on. But, for the Type 3 of unequilibrated meteorites, its difficult to determine their chemical groups exactly as the mineral composition varies in a large range and probably there is water in the meteorites. Related Articles | Metrics

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STUDIES ON THE TYPES OF 28 ANTARCTIC METEORITES 2002, 14 (4):  320-329.  Abstract ( 1328 )   PDF (347KB) ( 1196 )   The 28 Antarctic meteorites have been collected for the second time from the Grove Mountains of East Antarctica, during the 16th Chinese National Antarctic Research Expedition in 1999-2000 austral season. The 28 meteorites are all stones. According to the chondrule growing the meteorites can be divided into 5 types. GRV 99018 and GRV 99027 are achon-drites, other 26 meteorites are ordinary chondrites. These meteorites belong to different chemical groups ; H-group 5 , H/L-group 1, L-group have 9 , L/LL-group 2, LL-group 6, and L-group 3. Their petrologic types are: uneqquilibrated ordinary chondrites 5, the eqquilibrated ordinary chondrites 21. The majority are of types 4-6. Related Articles | Metrics

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METEORITE CHARACTERISTICS OF PETROLOGY- MINERALOGY AND CLASSIFICATION IN GROVE MOUNTAINS, ANTARCTICA 2002, 14 (4):  330-337.  Abstract ( 1313 )   PDF (818KB) ( 1106 )   Observations under microscope and electron probe analysis results of 28 new meteorites collected from the Grove Mountains ice field, Antarctica, by the 16th Chinese Antarctic Research Expedition, show that two meteorites belong to shergottites, and the other 26 meteorites are classified as ordinary chondrites, including 11 meteorites bearing high iron content ( H group) , 10 with low iron content (L group) and 5 with low iron and other metal phase contents ( LL group) . In H group, there are 5 primitive type 3 meteorites and 6 evolutional meteorites in which the later is further classified into 2 type 4 meteorites, one type 5 meteorite and 3 type 6 meteorites. For the L group, one type 3 meteorite, 2 type 4 meteorites, 2 type 5 meteorites and 5 type 6 meteorites are sub- classified, and 5 meteorites of LL group is also further classified into one type 4 meteorite, 3 type 5 meteorites and one type 6 meteorite. The two shergottites-GRV 99027 and GRV 99018 show they belong to new type meteorites with significance for researches, and are primary ascertained that GRV 99027 may belong to martian Iherzolite, and GRV 99027 may belong to eucrite. Related Articles | Metrics

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DISTRIBUTION OF THE PROGRESS IN THE SHOCK HISTORY AND SHOCK CLASSIFICATION OF METERORITES 2002, 14 (4):  338-343.  Abstract ( 1467 )   PDF (194KB) ( 1851 )   This paper reviews the new results on the studies of shock effects of meteorites, and the shock-related pressure and temperature history. According to the studies of maskelynite and the mineral assemblages in the shock veins, it seems that the nowadays shock classifications of meteorites should be further modified. We suggest that the shocked meteorites could be classified into two groups; the group-A contains high-density phases, such as maskelynite and other high-pressure minerals; the group-B contains low-density phases, for instance diaplectic feldspar glass, molten glass and the assemblages of low-pressure minerals. The group-A can be further divided into subgroups according to the types and occurrence of high-pressure minerals, whereas the group-B can be further divided into subgroups based on the degree of melting of minerals and meteorites. Related Articles | Metrics