Geochemistry of the Martian Meteorite GRV 99027

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 ΣREE 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 ΣREE 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 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-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.     

Cosmic-ray exposure age of Martian meteorite GRV 99027

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.     

南极陨石GRV 022115冲击熔融脉矿物学研究

文章主要通过电子探针、扫描电镜、激光拉曼光谱、透射电镜等微区微分析技术研究GRV 022115球粒陨石的基础矿物学特征和冲击变质矿物学特征，探讨陨石冲击熔融脉的形成机制和界定其母体的冲击条件。陨石主岩主要由橄榄石、辉石、熔长石、铁镍金属和硫化物等矿物组成。根据主岩的硅酸盐矿物学特征，确定GRV 022115是风化程度较低（W1） 的L6型普通球粒陨石，与前期分类结果一致。根据熔融脉内含有大量林伍德石的现象，修正GRV 022115陨石的冲击级别为S6，比原定的S5高一个级别。GRV 022115球粒陨石中有多条冲击熔融脉，熔融脉由基质和主岩碎块包裹体两类岩相组组成。熔融脉基质的主要组成是微米级粒状镁铁榴石与纳米级的含铁方镁石，是在平衡冲击压力下结晶的产物。冲击熔融脉主岩碎块包裹体中的橄榄石、低钙辉石、长石碎块已部分或全部转为相对应的高压相。橄榄石相变为林伍德石；个别低钙辉石相变为钙钛矿结构布里奇曼石微晶的集合体；长石主要相变为熔长石与玲根石。几乎所有的主岩碎块都有高温熔融的圆滑边界。熔融脉内外同类矿物的主量和微量元素具有一定的差异性，该差异性可以反映高温高压下混溶作用和扩散作用的影响。结合陨石冲击熔融脉形成机制和结晶模型，根据熔脉基质中镁铁榴石+方镁石矿物组合及静态高温高压实验相图，界定该陨石经受的冲击压力为23~27 GPa。     

南极GRV9927陨石：一种可能的火星陨石

自 1 969年日本冰川学家首次发现南极无球粒陨石以来 ,南极冰原为人类提供了无与伦比的地外物质 ,包括大多数月球陨石及近半数的火星陨石。据ＭｃＳｗｅｅｎ报道[1] ,已有 1 3个陨石确定为火星陨石 ,其中包括ＡＬＨＡ770 0 5和ＡＬＨ 840 0 1陨石。 1 996年美国航空航天局ＭｃＫａｙ等宣布 ,他们在ＡＬＨ840 0 1火星陨石中发现了生命活动的遗迹。这一发现引起了各国科学家的极大兴趣 ,并引发了一场激烈的争论。因此 ,火星陨石的研究受到了人们广泛的关注。作者研究的ＧＲＶ992 7陨石样品是 1 999年我国南极科学考察队中国科学院地质研究所刘…     

GRV 99027火星陨石的岩石学和矿物学特征

GRV 99027陨石是二辉橄榄岩质辉玻无球粒陨石(L-S)的火星陨石新成员,具有嵌晶、非嵌晶和冲击熔融袋结构。矿物模式组成以橄榄石(55%)、辉石(37．5%)为主,有少量熔长石(6%)、铬铁矿(1．5%)以及微量白磷钙石、陨硫铁等。其矿物的化学成分较为均一,无分带现象。橄榄石组分为Fo_(69．1～76．6)Fa_(23．4～30．9),平均Fo_(72．4)Fa_(27．6),低钙易变辉石为En_(59．3～75．1) Fs_(20．5～26．9)Wo_(3．1～14．9),平均En_(68．6)Fs_(23．5)Wo_(8．0),普通辉石为En_(46．6～53)Fs_(13．1～16．1)Wo_(31．9～37．8),平均En_(50．7)Fs_(14．5)Wo_(34．8),熔长石为An_(43．6～59．3) Ab_(40．2～54．6)Or_(0．5～1．8),平均An_(52．4)Ab_(46．7)Or_(0．8)。该陨石的结晶顺序是：亏损的火星幔源区部分熔融形成的原始母岩浆最先结晶的是嵌晶区的橄榄石和铬铁矿,随后易变辉石晶出,呈主晶包裹橄榄石和铬铁矿；此后,橄榄石、易变辉石、普通辉石持续结晶,直到残余熔体在晶隙形成斜长石和白磷钙石等。在这陨石中的易变辉石和普通辉石共存,二辉石温度计显示平衡温度为1000～1190℃(平均≈1146℃)。GRV 99027经历的亚固相再平衡,其程度为ALH 77005≈GRV 99027＞LEW 88516＞Y 793605。GRV 99027经受的冲击压力为30～45 GPa,,局部达到60～80GPa,冲击后温度可能＜600℃。     

南极格罗夫山陨石GRV 020043—一个特殊的E/H过渡型球粒陨石

南极格罗夫山陨石GRV 020043是一块特殊的球粒陨石,虽与普通球粒陨石有着相似的矿物组合,但矿物成分超出普通球粒陨石范围.主要矿物组合及其模式含量(vol%)是:斜方辉石40、橄榄石24、透辉石8、斜长石10、 Fe-Ni合金14、陨硫铁4 vol%、及少量铬铁矿和磷灰石.主要组成矿物成分均一,如斜方辉石(Fs10...     

几种特异值处理方法的比较

特异值（又称特高品位）存在于抽样调查之中。在地质统计学中，如果观测值存在有特异值，就严重的影响变差函数的计算结果，从而大大影响了地质统计学研究结果的精度。本文通过对目前国内外处理特异值方法（１．估计邻域法ＥＮＭ２．影响系数法ＩＣＭ３．相对变差函数法ＧＲＶ．ＰＲＶ）的比较，确定处理方法的优劣，对提高地质统计学研究结果的精度，有积极的作用     

CO observations of Southern molecular clouds. Outflows from young stellar objects GRV 8 and GRV 16

¹²CO (1-0) observations of two Southern dark clouds (globules) associated with cometary nebulae GRV 8 (a biconical nebula) and GRV 16 (a conelike nebula) are presented. GRV 8 shows an outflow from the central part of the nebula (where in 2MASS images a star is located, which is perhaps responsible for this outflow); however, both lobes of the outflow are redshifted with a velocity of +1.95 km/s with respect to the molecular cloud. The two opposite redshifted lobes are a rather rare phenomenon that could be explained by the presence of a double star instead of a single one as the engine responsible for the outflow. The two lobes are almost parallel to the axis of symmetry of the biconical nebula. In the case of the conelike nebula GRV 16 we observe a bipolar outflow, where the eastern blueshifted lobe has a velocity of –4 km/s with respect to the molecular cloud, and the western redshifted one has a velocity +2.5 km/s. The outflow has a direction almost coinciding with the axis of symmetry of the conelike nebula. The star associated with the conelike nebula is responsible for this outflow.Published in Astrofizika, Vol. 48, No. 1, pp. 101–112 (February 2005).     

南极格罗夫山陨石GRV053645的岩石矿物学特征

南极格罗夫山陨石GRV053645是一块非常原始的普通球粒陨石,它很好地保存有太阳星云凝聚和增生的相关信息,对研究太阳星云的起源意义重大。本文描述了这块陨石的岩石矿物学特征,包括球粒结构类型、基质不透明、橄榄石和低钙辉石具有明显的成分环带等。根据Fe-Ni合金含量、球粒平均直径大小和橄榄石平均Fa值,表明这块陨石属于低铁群(L)。利用橄榄石Fa的PMD值与岩石类型亚类的相关性,其岩石类型应为3.4亚类。该陨石冲击变质程度和风化等级都比较低,分别为S2和W1。     

南极GRV 99027火星陨石的地球化学特征

南极GRV 99027陨石是二辉橄榄岩质辉玻无球粒陨石(L-S)的火星陨石,具有嵌晶、非嵌晶和冲击熔融袋结构。矿物模式组成以橄榄石(55%)、辉石(37.5%)为主,有少量熔长石(6%)、铬铁矿(1.5%)以及微量白磷钙石、陨硫铁等。本文在阐述该陨石的岩石学和矿物化学特征的基础上进一步研究了稀土元素及氢同位素的地球化学特征。该陨石∑REE总量低;橄榄石及辉石以HREE富集为特征;熔长石富LREE,且具高正的δEu;副矿物白磷钙矿含量虽少(约0.2%),但具有极高的∑REE,LREE≈HREE,δEu负异常明显。GRV99027全岩稀土元素分配模式与L-S陨石的模式十分相似,而与SNC其它类型陨石的REE分配模式不同,反映不同类型火星陨石物质源区不同。火星陨石氢同位素以高δD为特征,各类含水矿物对陨石δD的贡献不同。陨石磷酸盐矿物中δD-水含量间一般没有正相关性,间或存有弱的负相关性。根据GRV99027陨石的矿物学模式,REE分配模式,及氢同位素特征,可以确定GRV99027陨石为L-S陨石。为了探讨GRV99027陨石的物质源区及演化历史,我们广泛收集了L-S火星陨石的Sr,Nd,Pb,Os和稀有气体同位素...