东南极拉斯曼丘陵暗色麻粒岩锆石的U—Pb年龄及其地质意义

东南极拉斯曼丘陵地区代表性的原岩为镁铁质岩的暗色麻粒岩，其中猪石的Ｕ－Ｐｂ同位素年代测定表明，本区在泛非事件之间的晚元古中期可能经历过一次麻粒岩相变质作用主要由斜方辉石－单斜辉石－斜长石－石英组成的暗色麻粒岩的Ｕ－Ｐｂ不一致年龄结果为７７２．４＋７１．１／－４８．０Ｍａ。     

东南极拉斯曼丘陵暗色麻粒岩锆石的U-Pb年龄及其地质意义

东南极拉斯曼丘陵地区代表性的原岩为镁铁质堆晶岩的暗色麻粒岩，其中锆石的Ｕ－Ｐｂ同位素年代测定表明，本区在泛非事件（５００Ｍａ）之前的晚元古中期可能经历过一次麻粒岩相变质作用，主要由斜方辉石－单斜辉石－斜长石－石英组成的暗色麻粒岩的Ｕ－Ｐｂ不一致线年龄结果为７７２．４＋７１．１／－４８．０（２σ）Ｍａ。结合野外地质证据，此年龄可能代表了该区已识别出的早期中压麻粒岩相变质作用事件并对应于罗迪尼亚事件     

东南极普里兹湾Sφstrene岛麻粒岩变质年代及其与邻区的关系

对东南极普里兹湾Ｓｓｔｒｅｎｅ岛石榴辉石麻粒岩的变质年龄通过Ｓｍ－Ｎｄ法做了重新测定，得出６０４±２８（２σ）Ｍａ的石榴石－辉石－斜长石－全岩矿物内部等时线年龄，并指出本数值代表了该区主期中压麻粒岩相变质年龄。至于与其北东部的Ｂｏｌｉｎｇｅｎ群岛、拉斯曼丘陵的关系，通过岩石组合，变质叠加及其空间变化特征并结合变质时代推断，自Ｓｓｔｒｅｎｅ岛至拉斯曼丘陵后期低压变质叠加逐渐增强，早期中压及晚期低压变质可能代表了同一变质旋回的不同阶段     

东南极普里兹湾Sφstrene岛麻粒岩变质年代及其与邻区的关系

对东南极普里兹泫Ｓφｓｔｒｅｎｅ岛石榴辉石麻粒岩的变质年龄通过Ｓｍ－Ｎｄ法做了重新测定，得出了６０４±２８Ｍａ的石榴石－辉石－斜长石－全岩矿物内部等时线年龄，并指出本数值代表的该区主期中压麻粒岩相变质年龄。至于与其北东部的Ｂｏｌｉｎｇｅｎ群岛拉期曼丘陵的关系，通过岩石组合，变质叠加及其空间变化特征并结合变质时代推断，自Ｓφｓｔｒｅｎｅ岛至拉斯曼丘陵后期低压变质叠加逐渐增强，早期中压及晚期低压变质可     

兴和岩群二辉麻粒岩中超贫磁铁矿的赋矿特征

兴和岩群按斜长石和二辉石的含量进一步划分为二辉麻粒岩、二辉斜长麻粒岩、长英质麻粒岩等。其中,二辉麻粒岩含磁铁矿品位在mFe5%~12%,为超贫磁铁矿的主要赋矿层位[1],本文研究了兴和岩群中二辉麻粒岩的岩石学、岩石化学特征、原岩环境以及所含超贫磁铁矿品位、选矿一般工艺流程等。     

南极MIL 090070月球陨石的岩石矿物学特征

MIL 090070陨石是2009年美国南极陨石搜寻项目(ANSMET)在南极横断山脉米勒山区(Miller Range)发现的一块月球陨石,属于斜长岩质月表角砾岩。它具有典型的碎屑结构,主要由岩屑、晶屑、玻屑和细粒基质组成。岩屑以复合斜长岩质岩屑和斜长岩岩屑为主,其次为辉长岩质斜长岩岩屑、辉长岩岩屑、辉长苏长岩岩屑、辉长岩质橄长岩岩屑和橄榄辉长岩岩屑等。晶屑有普通辉石、易变辉石、斜长石、尖晶石、石英和钛铁矿等矿物。玻屑主要为斜长石质的玻屑,呈细长或弯曲条状,多具裂纹。MIL 090070陨石的矿物组成主要为斜长石（86 vol%,An92—99）、橄榄石（6 vol%,Fo53—89）、辉石（7 vol%,En25—83Fs7—43Wo2—45）,以及少量的尖晶石、钛铁矿和石英等;其中,辉石有单斜辉石和斜方辉石二种。MIL 090070陨石中橄榄石和辉石的Fe-Mn值分布明显不同于地球、火星、金星和小行星的样品,基本落在月球岩石范围。MIL 090070陨石在多期次冲击和胶结作用下,岩屑的矿物成分和粒度不断变化,岩屑类型更多样,更复杂。基于MIL 090070陨石的岩石矿物学特征、碎屑类型及结构的特征等研究,可以进一步丰富我们对月球物质的形成及月岩—月壤演化过程的认识。     

南极半岛西北部海域表层沉积物碎屑矿物研究

本文通过对南极半岛西北部海域23个表层沉积物中碎屑矿物分析研究,获得以下结果:1.主要矿物有单斜辉石、斜方辉石、角闪石、绿帘石、磁铁矿、钛铁矿、黄铁矿、白云母、黑云母、绿泥石、橄榄石,玄武闪石、石榴石、磷灰石、锆石、金红石及火山玻璃、斜长石、石英等;2.根据矿物分布特征和稀土元素特征本区可分为三个矿物区和三种矿物组合类型:①基性火山碎屑矿物沉积区,矿物组合类型为辉石-火山玻屑型;②中酸性火成矿物沉积区,矿物组合类型为辉石-绿帘石-角闪石-石英;③基性火山碎屑矿物和变质矿物混合沉积区。矿物组合类型为辉石-绿帘石-石榴石-石英-火山玻屑。     

西南极利文斯顿岛中部中－新生代火山岩的岩相学和矿物学特征

出露在利文斯顿岛中部的中－晚白垩世火山碎屑岩为多源的角砾凝灰岩、角砾岩和集块碎屑岩，成分以安山质为主。橄榄玄武岩主要在史莱夫角出露，为全晶质斑状构造；主要出露在中利文斯顿和汉那角的安山岩、玄武安山岩多具细晶微斑构造。更新世至现代的火山岩为全晶质斑状的橄榄玄武岩和火山碎屑岩。熔岩的基本矿物组合大致相似，均为斜长石＋辉石（＋橄榄石）＋铁的氧化物，但矿物的含量比例因岩性不同而有所区别。岩石中的斜长石斑晶多具正环带；随着岩石ＳｉＯ２含量的增加，斜长石中Ｏｒ和Ａｂ组分增加而Ａｎ含量下降，斑晶边缘成分一般与基质里长石的成分相近。安山岩和玄武安山岩含有中长石－拉长石斑晶，玄武岩主要含拉长石斑晶，但橄榄玄武岩和粗玄岩中斜长石斑晶的核部为富钙的倍长石。更新世－现代的橄榄玄武岩，其所含斜长石斑晶和基质长石亦比较富钙。玄武安山岩中的辉石多为普通辉石，橄榄玄武岩和玄武岩中含有透辉石斑晶。辉石的Ｔｉ含量低，这是钙碱性火山岩的共同特点。史莱夫角的橄榄玄武岩含有贵橄榄石斑晶。粗玄岩中橄榄石成分与史莱夫角基质橄榄石成分相近。更新世至现代的橄榄玄武岩中既有正常结晶的橄榄石斑晶，还见到高Ｆｏ组分的深源捕掳晶。上述玄武岩中矿物组合的基本特征证明     

一块新发现月球陨石MIL090036的岩相学和矿物学

MIL090036是一块在南极新发现的月球陨石,属于斜长岩质月球角砾岩。本文对这块陨石开展了详细的岩石学、矿物学特征观察与研究。MIL090036月球陨石具有典型的碎屑结构。碎屑包括岩屑、矿屑和玻屑。岩屑类型有斜长岩岩屑、辉长质斜长岩岩屑、辉长岩岩屑、风化角砾岩岩屑、橄长岩岩屑、微斑熔融角砾岩岩屑、复合角砾岩岩屑等;矿屑有辉石、斜长石、橄榄石、钛铁矿等;玻屑主要为长石质。基质由玻璃质、重结晶的细粒矿物和矿屑胶结组成。辉长岩岩屑中的斜长石（An81-83）和斜长岩中的斜长石(An88-93)较其他碎屑中的斜长石(An90-98)贫钙。岩屑、矿屑和长石质玻屑中的辉石相对贫铁（Fs 12-35Wo3-44 En22-79）,而含玻璃质的辉长岩岩屑中的辉石（Fs37-65Wo10-29 En21-49）与基质中的辉石（Fs18-69Wo3-45 En14-50）相对富铁。辉长岩质斜长岩中辉石成分变化范围最小（Fs24-27Wo7-14 En59-69）。矿屑橄榄石和分布于基质中的橄榄石铁镁含量（Fo57-79）相对岩屑中的橄榄石(Fo67-77) 变化范围大。橄榄石Fe/Mn比值为47-83（平均76）、辉石Fe/Mn比值为76-112（平均73）,都与月球橄榄石和月球辉石一致。岩石结构、矿物模式组合和化学成分等特征表明MIL090036是来自Apollo和Luna采样范围外的样品。对MIL090036的矿物学、岩石学和化学成分的进一步研究将能够丰富我们对月表物质组成和演化的认识。     

南极陨石研究的启示Ⅷ:原始无球粒陨石及其成因

近年来,在南极和非南极地区回收的异常陨石中已识别８个原始无球粒陨石群：斜方辉石－橄榄石无球粒陨石、富橄榄石无球粒陨石、橄榄古铜陨铁、橄辉无球粒陨石、顽辉石－镁橄榄石无球粒陨石及ＡＢ－ＣＤ硅酸盐、顽辉石无球粒陨石及钛辉无球粒陨石。斜方辉石－橄榄石无球粒陨石及橄榄古铜陨铁具有相似的矿物学、矿物成分、热历史、氧同位素组成及宇宙射线暴露年龄,他们系来自共同的母体。ＡＢ－ＣＤ硅酸盐及顽辉石－镁橄榄石无球粒陨石的氧同位素组成、化学及矿物学也相似,认为他们来自共同的母体。在考察岩石学证据的基础上,将ＡＢ－ＣＤ硅酸盐和顽辉石－镁橄榄石无球粒陨石、富橄榄石无球粒陨石、斜方辉石－橄榄石无球粒陨石及橄榄古铜陨铁以及橄辉无球粒陨石划分为非岩浆型的原始无球粒陨石,他们为高度变质并伴随不同程度部分熔融的岩石;而顽辉石无球粒陨石及钛辉无球粒陨石为火成岩石,但未受到广泛的分异作用和分异形成不同岩性的岩石,将其划分为岩浆型的原始无球粒陨石。到目前为止,共有六个原始无球粒陨石母体。     

Inferred ultrahigh-temperature metamorphism of amphibolitized olivine granulite from the Sør Rondane Mountains, East Antarctica

This paper reports the first evidence of ultrahigh-temperature (UHT) metamorphism from the Sør Rondane Mountains, eastern Dronning Maud Land, East Antarctica, which is evident as orthopyroxene + spinel symplectite in an amphibolitized mafic granulite. The granulite consists of olivine, orthopyroxene, clinopyroxene, pargasitic amphibole, plagioclase, and ilmenite, and it possesses a within-plate alkali basalt signature. The local bulk chemical composition of symplectite, major and trace element compositions, and thermodynamic calculations for the symplectite, suggest the presence of garnet at the high-pressure stage and that the symplectite formed from garnet, olivine, and primary orthopyroxene by decompression from more than 12 kbar at 1000 °C. The granulite records a subsequent amphibolite-facies overprint (<700 °C at <6 kbar) that involved the chemical re-equilibration of several phases. The obtained pressure–temperature (P–T) conditions and P–T path are different from the UHT metamorphism from the Schirmacher Hills, central Dronning Maud Land, which is considered to have occurred in a back-arc tectonic setting. The relatively high-P conditions and the decompression path reconstructed in the present study are similar to those reported for southern India, Sri Lanka, and part of northeastern Mozambique, possibly reflecting continental thickening and exhumation during the main collision event between East and West Gondwana.     

~(40)Ar/~(39)Ar IsOTOPIC DATING THE BIOTITES FROM THE IGNEOUS AND METAMORPHIC ROCKS OF THE ZHONGSHAN STATION AREA

The Zhongshan Station of China is located in the Larsemann Hills, East Antarctica. Low pressure granulite facies gneisses together with late granites are outcroped in the region. Three biotite samples from a garnet segregation, a syenogranite and a granite-pegmetite were measured with ~(40)Ar/~(39)Ar incremental heating technique. Biotites from the garnet segregation give an ~(40)Ar/~(39)Ar plateau age of 504±1Ma. Biotites from the syenogranite yield an ~(40)Ar/~(39)Ar plateau age of 494±1 Ma. Biotites from the granite-pegmatite give an ~(40)Ar/~(39)Ar plateay age of 486±1Ma. They verify 500 Ma thermal event called "Pan African event" by previous K-Ar and Rb-Sr data. They are cooling ages of the biotites when the paleogeotherm of the area droped to the K-Ar closure temperature for biotite.     

A Sm－Nd mineral isochron of mafic granulite from the Sφstrene Island， East Antarctica

任留东，刘小汉ＡＳｍ－ＮｄｍｉｎｅｒａｌｉｓｏｃｈｒｏｎｏｆｍａｆｉｃｇｒａｎｕｌｉｔｅｆｒｏｍｔｈｅＳφｓｔｒｅｎｅＩｓｌａｎｄ，ＥａｓｔＡｎｔａｒｃｔｉｃａ￥ＲｅｎＬｉｕｄｏｎｇ（ＩｎｓｔｄｕｔｅｏｆＧｅｏｌｏｇｙ，ＣｈｉｎｅｓｅＡｃａｄｅｍｙｏ...     

南极中山站地区正长花岗岩及花岗伟晶岩脉的~(40)Ar/~(39)Ar同位素年龄测定

本文详细报道了用 4 0 Ar/3 9Ar定年法测定的二个黑云母样品的数据结果。样品来自拉斯曼丘陵米洛岛北部中国南极中山站附近。一个取自正长花岗岩 ,另一个取自侵入正长花岗岩的花岗伟晶岩脉。正长花岗岩的 4 0 Ar/3 9Ar坪年龄为 494.4± 1 .4Ma,花岗伟晶岩脉的 4 0 Ar/3 9Ar坪年龄为 485 .8± 0 .6 Ma。两者为区域泛非热事件晚期阶段的产物。     

Origin of sapphirine-bearing garnet-orthopyroxene granulites: possible hydrothermally altered ocean floor

Sapphirine is a metamorphic mineral that forms in the deep crust in rocks with distinctive bulk compositions, in particular high concentrations of Mg and Al. This study investigates a thin, discontinuous layer of sapphirine-bearing garnet-orthopyroxene (SGO) granulite within a Palaeoproterozoic mafic granulite together with metamorphosed mafic and ultramafic rocks, micaceous rocks rich in magnetite and pyrite, and marble. All of these rocks occur within a low-strain zone in the Lewisian complex of South Harris, NW Scotland. Data on mineral compositions and major, trace, and rare earth element (REE) patterns provide evidence for the origin of the precursor of the SGO granulite. The host mafic granulite has a trace element signature and REE pattern comparable with that of E-type MORB. The chemical abundances of Nb, Ta, La, Ce, Nd, Zr, Hf, Ti, and V in the SGO granulite, except for one sample that records total element loss, are similar to those of the host mafic granulite; however, in terms of whole-rock element abundances, the former is relatively enriched in MgO and depleted in CaO, Na₂O, MnO, Sr, and Eu. Elements within the SGO granulite that were apparently unaffected by hydrothermal alteration—V, Y, Zr, and Cr—are within the range of values observed in the host mafic granulite. Sm–Nd whole-rock isotope systematics suggest that both the host mafic granulite and SGO granulite were metamorphosed at 1.9 Ga, and the Nd initial ratio is consistent with a MORB source at that time. There is no significant difference in the Nd values of the two rock types, suggesting that they originally belonged to the same protolith. Chemical trends within a narrow zone between the SGO and host rock granulite suggest that the former was derived from a basaltic precursor of the latter by a process of infiltration metasomatism, comparable with the chemical exchange that takes place when hydrothermal fluids in present-day oceanic crust pass through vents in a “recharge zone.” The geological and chemical relations observed in the South Harris rocks are consistent with the following model: hydrothermally altered oceanic basaltic crust was trapped in an accretionary wedge and subducted, followed by granulite-facies metamorphism in a deep continental environment during arc–continent collision. This is the first report of hydrothermally altered oceanic crust that was converted to sapphirine-bearing granulite deep in the continental crust.     

AN OCCURRENCE OF THE ASSEMBLAGE GRANDIDIERITE, KORNERUPINE, AND TOURMALINE IN ANTARCTICA

Grandidierite, kornerupine, and tourmaline occur in high-grade pelitic gneisses from the Larsemann Hills, East Antarctica. The three minerals contact to each other and show a special order: Trn_1→Gdd→Trn_2→Krn→Trn_3, suggesting the occurrence of the assemblage is controlled by the temporal changes of the chemical potentials of B_2O_3 and H_2O. The discovery of the assemblage is a good constraint on the seting and composition feature of metamorphism in the area.     

南极拉斯曼丘陵中山站地区Rb含量初步调查

利用手持快速矿石分析仪(NITON XL3t-500S GOLDD)对拉斯曼丘陵中山站附近出露的基岩进行测试, 初步调查结果显示该地区有明显的Rb元素富集。测试了17个样品, 其中12个的Rb含量达到了0.04%, 1个样品的Rb含量达到0.1%以上。分析测试样品特征, 并结合拉斯曼丘陵地质特征发现, 拉斯曼丘陵地区Rb的富集与含黑云母的泛非期伟晶岩墙关系密切, 而且粒度越大Rb含量越高, 类比推测该区域Rb元素富集潜力巨大, 有必要继续开展相应的地质调查工作, 进一步探讨其富集成因和规律。     

南极中山站固体潮观测分析

中国南极中山站位于南极拉斯曼丘陵地区（λ＝７６°２２′Ｅ，φ＝６９°２２′Ｓ），１９９１年３月至１９９３年２月，用ＬａｃｏｓｔｅＥＴ型重力仪，在这个地区进行了为期近两年的观测，取得了６００多天的有效资料，经调和分析和流变模型、海潮负荷改正后得到：δｏ１＝１．２２５３±０．００３１，Δφｏ１＝０．７３°±０．１４°；δｍ２＝１．０７８５±０．００４５，Δφｍ２＝－３．５５°±０．２９°从资料分析的精度来看，观测资料是比较好的；但由于海潮负荷改正缺少附近海域的资料，会对最终结果造成较大的影响