Meteorites usually derive from primitive materials that condensed and accreted from the gas-and dust-containing presolar disk.Most of them were altered by postaccretionary processes(as in lunar,terrestrial,and martian samples),but some survived essentially integrity(as chondrites or inclusions in chondrites).These primitive chondrites are recognizable usually from isotopic abundance characteristics.Based on mineral-petrologic characteristics and their origin we can classify known meteorites into a much smaller number of types.Recent advance in miteoritic and cosmochemistry include the newly recognized meteorite groups;discoveries about the presolar and nebular components of chondrites and interplanetary;improvements in early solar system chronology using short-radionuclides;new insights into cosmochemical abundances;fractionation,and nebular reservoirs;and advance explanation for nebular and prenebular records of secondary parent body processes.We summarized evolved process from nebula to meteorite in early solar system.Some new insights based on these data are that the early solar system experienced a variety of nucleosynthetic input,the dynamic entity with transient heating events,and the system of plantesimals and planets evolved more rapidly than previously expected.

Antarctic meteorite survey has been one of the most important Antarctic expedition projects of many countries since the middle of the last century.China Antarctic Research Expedition(CHINARE) began to search meteorites in Antarctica at the end of the last century,and has obtained great achievements in the new century.During the first decade of this century,CHINARE has collected more than ten thousands Antarctic meteorites,China became one of the richest countries with Antarctic meteorites,and had found a new meteorite concentrated area in East Antarctica-Grove Mountains.

The physical and petrologic properties of the different chondrite groups,including mean size of the chondrules,proportions of the chondrule textural types,proportions of compound chondrule,the proportions of chondrules with igneous rims,and the proportions of chondrules that contain sulfide,chemical compositions and mineral features derived from the early solar nebula are used to classify chemical-petrologic types and asteroids.These properties provided useful taxonomic parameters for different chondrite group(EH,EL,H,L,LL,R,CV,CK,CR,CM,CO) and the information of their formation environment in which chondrules formed.There is correlation between -17O and heliocentric distance for these chondrite groups.Thus,different chondrite groups may be put in the order of EH-EL,OC(H,L,LL),R,CR,CV-CK,CM-CO,with increasing heliocentric formation distance,based on the amount of dust present where they formed and -17O values of different chondrite groups.We infer that continual chemical fractionation occurred in the early solar system.

Chromium isotope compositions have been widely applied in cosmochemistry and are a record of the early evolution of the Solar System.The major methods employed to measure Cr isotopic compositions are SIMS,TIMS and MC-ICPMS.This paper reviews the characteristics and development of these analysis techniques.With development of analytic techniques,the current analytical precisions for ε(53Cr) and ε(54Cr) are 6 and 12 ppm(2 σ),respectively.The subtle variation in Cr isotopic compositions in extraterrestrial materials can be determined by highly precise measurement of Cr isotopes.This advantage provides a new way to further clarify and evaluate the origin and distribution of 53Cr and 54Cr in the Solar System.

Ca-, Al-rich inclusions (CAIs) are the earliest assemblages formed in the solar nebula. The formation models of CAIs include gas—soild condensation, crystallization from melting or partial melting and high-temperature evaporating residues. The latest study show similar distribution patterns of the petrographic types and sizes of CAIs in various chondrites. The petrographic characters argue that CAIs in various chemical groups of chondrites formed under similar processes and conditions probably in a same region in the solar nebula. This is consistent with previous studies of oxygen isotopes, Al—Mg isotopic system and rare earth elements, which suggest a same reservoir of CAIs in various chondrites.During and/or after formation, CAIs were transported into different locations where various groups of chondrites accreted.

The accretion and formation processes of different type of chondrite parent body are referred to as indicators of evolution history of early solar nebula. They include pre-solar grains in primitive chondrites providing information of stellar evolution outside solar system. Mineralogic-petrologic characteristics of primitive chondrites reveal process of condensation and accretion in the early solar nebula. Oxygen isotopic composition of the major components in primitive chondrites may provide strong evidence of precursor materials and formation environment for the chondrites of different types. Formation ages of Ca-Al-rich inclusions and chondrules may speculate the time-scale of evolution of the early solar nebula. The features of oxidation-reduce process of primitive chondrites can be deduced formation location of the primitive chondrites of different types in early solar nebula and distance from the sun. All of these we can propose chemical evolution of early solar nebula.

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 24 H-group(13 H4,10 H5,1 H6),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(W1 and W2).About half of the meteorites experienced severe shock metamorphism.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 Transantarctic Mountains.

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 type meteorites.In addition,we propose to continue the meteorite 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.

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 special meteorites,e.g.Martian meteorites,ureilites and carbonaceous chondrites,have been classified.（2）the Antarctic meteorite curation and the sample sharing system are set up preliminarily.（3）the classification procedure,the management 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 on meteorite classification.

The petrography and mineral chemistry of 6 unequilibrated ordinary chondrites collected from the Grove Mountains,Antarctica,were studied.All meteorites show highly primitive petrography and mineral chemistry,as indicated by very shape-outlined chondrules,almost opaque fine-grained matrix,zoned grains of olivine and low-Ca pyroxene,and wide compositional ranges among grains.According to their petrography and mineral chemistry data,these meteorites are classified as 3 H3 and 3 L3 chondrites.Based on the relationship between the Percent Mean Deviation(PMD) of Fa of olivine and subtype of unequilibrated ordinary chondrites,they are subdivided with GRV 020016 as H3.7,GRV 020162 as H3.5,GRV 020166 as H3.4,GRV 020106 as L3.7,GRV 020164 as L3.7,and GRV 020165 as L3.7.We found these chondrites all experienced low-degree weathering and week shock metamorphism.

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 evolution 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 olivine.GRV 052382 probably experienced heavy shock metamorphism followed by fast cooling,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 are 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.

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 unequilibrated,as indicated by well shaped chondrules and the chemical variations of olivine and low-Ca pyroxene.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—2.0 mm).A total of 30 Ca-Al-rich inclusions were found in the four meteorites.Most inclusions were highly altered,with abundant phyllosilicates in the inclusions of GRV 020017 and GRV 020025.On the base of petrography and mineral chemistry,these chondrites are classified as CM2(GRV 020017 and 020025),CO3(GRV 021579)and CV3(GRV 022459).

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 primitive meteorites,also extended to mass-dependent fractionation of Mg isotopes in meteorites and terrestrial rocks.This paper reviews recent development in Mg isotope researches.

Petrography and mineral chemistry of 100 meteorites collected from the Grove Mountains,Antarctica,were studied and their chemical-petrographic types were assigned.The chemical-petrographic types of these meteorites are presented below.Six are unequilibrated ordinary chondrites,including three H3 and three L3;92 meteorites are equilibrated ordinary chondrites,including 24 H-group(13 H4,10 H5,1 H6),64 L-group(2 L4,44 L5,18 L6) and 4 LL-group(3 LL4,1 LL5);the other two belong to stone-iron meteorites.In 6 unequilibrated ordinary chondrites,chondrules are well-shaped,and olivine and low-Ca pyroxene are commonly zoned and have wide ranges of composition.The olivine and low-Ca pyroxene in the other 92 equilibrated ordinary chondrites have similar composition,respectively,and to some degree it reflected thermodynamics equilibration in olivine and lowCa pyroxene.All ordinary chondrites,consisting of predominant weathering degrees of W1 and W2(>90%),suggest a weak weathering among Antarctica meteorites.~40 % meteorites experienced severe shock metamorphism,as indicated by the presences of shock-induced melt veins and pockets.These heavily shocked meteorites provide us with natural samples for study of high-pressure polymorphs of minerals.

介绍南极格罗夫山地区新发现的二块橄辉无球粒陨石的岩石学特征和矿物化学.GRV021512陨石具有典型的橄辉无球粒陨石结构,主要由橄榄石(48.3%)、易变辉石(9.4%)和富碳质填隙物(38.1%)组成.而GRV 022931为碎裂斑状结构,橄榄石(19.1%)和易交辉石(14.1%)呈斑晶状分布于富碳质填隙物和蚀变产物(66.3%)中.二块陨石的粗粒橄榄石和易变辉石都具有均匀的核部成分,其成分富FeO,落在橄榄石一易变辉石橄辉无球粒陨石的富铁的亚群(I型)中.所有橄榄石沿颗粒边缘和裂隙表现出还原边结构.在富碳质填隙物中石墨呈不规则块状或脉状产出,其中有大量细小的金刚石与之共生.此外,还讨论了二块陨石的岩石成因和金刚石成因.

Based on the petrologic characteristics by optical microscope and analyses of mineral chemistry by electronic microprobe,100 meteorites collected from Grove Mountains,Antarctica,are classified into different chemical groups,rock types,shock stages and weathering degrees.Eight of them are classified into H4,15 into H5,3 into H6,1 into L3,2 into L4,16 into L5,47 into L6,5 into LL3,1 into LL4,and 2 into LL5.Furthermore,according to their petrologic features and mineral chemistry,21 groups of meteorites are preliminarily paired.

Ice field exploration,classification and studies of meteorites from Grove Mountains,Antarctica,are reviewed.A total number of 9834 meteorites have been collected during 4 times of the explorations in this region.2431 meteorites out of the collection will be classified by the end of 2008.Of 685 meteorites published in the Meteoritical Bulletin Database,there are 2 martian meteorites,2 eucrites,6 ureilites,5 mesosiderites,1 pallasite,1 iron,and 10 carbonaceous chondrites.Comprehensive studies on these rare types are also summarized in this paper.We suggest continuing Antarctic meteorite searching and classifying projects,and propose key research topics of the Antarctic meteorites.

Petrography and mineral chemistry of two new ureilites, GRV 021512 and 022931, from the Grove Mountains, Antarctica, are reported in this paper. GRV 021512 exhibits a typical ureilite texture, and consists of 48.3% olivine, 9.4% pigeonite and 38.1% carbonaceous interstitial material and/or reduction product. GRV 022931 has a cataclastic porphyritic texture, and consists of 19.1% olivine and 14.1% pigeonite embedded in 66.3% carbonaceous interstitial material and/or reduction product. The coarse-grained olivine and pigeonite in both meteorites have homogeneous cores, and they are FeO-rich within the range of the ferroan subgroup (subgroup I) of olivine-pigeonite ureilites. All olivine grains of the meteorites show reduction zones along boundaries and cracks. Abundant diamond coexists with graphite as graphite-rich patches and veins in the carbonaceous interstitial material. Petrogenesis of both meteorites and the origin of diamond are discussed.

Meteorites are the extraterrestrial rocks,which provide insights into the origin and evolution of the solar system.In the past half century,a great number of meteorites have been discovered on the Antarctic Ice Sheet,confirming that the Antarctica is the most important meteorite concentration in the earth.Since the first four Antarctic meteorites were found in Grove Mountains in 1998,a total number of 9834 meteorites have been collected by four expeditions.It breaks 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 some progresses have been made:(1) 684 meteorites,including many special meteorites,e.g.Martian meteorites,ureilites and carbonaceous chondrites,have been classified;(2) The Antarctic meteorite house and the sharing net system are set up preliminarily;(3) The classification procedure,the management of meteorite samples,and the application procedure for the Antarctic meteorites are completed after the systematic classification during these years;(4) The young scientists are trained through the cooperation of many universities and institutes on meteorite classification.

The GRV 024516 and GRV 024517 meteorite samples collected from Grove Montains,Antactica are ureilite and H5 ordinary chondrite,respectively.Based on the study of mineralogy-petrology,the cosmic-ray exposure ages and gas retention ages of these two meteorites were determinated and calculated.Their cosmic-ray exposure ages are 33.3 Ma,51.7 Ma,and gas retention ages are 1936.8 Ma and 3720 Ma,respectively.The ureilite contains diamond,graphite and amorphous C,which are mainly carrier of noble gases indicating obviously shock metamorphism effects,which induced 40Ar partial loss.The H5 chondrite indicates thermal metamorphism of parent body,its gas retention age fall the range between 3220 Ma and 4510 Ma of the least shocked H5 chondrites