西准噶尔夏尔莆岩体岩浆混合岩石化学证据

夏尔莆岩体是西准噶尔地区较典型岩浆混合花岗岩.岩体由寄主岩石(中酸性侵入岩)、微粒镁铁质包体和中基性岩墙群3部分组成.寄主岩石(中酸性侵入岩)与微细粒镁铁质包体具相似岩石化学特征,有明显元素双扩散现象.在图解中,寄主岩石具良好线型岩浆混合演化特征,微细粒镁铁质包体也位于演化趋势上,显示两者具共同成因联系,中基性岩墙群具独立演化趋势,属不同岩浆端元.岩石化学显示的岩浆混合信息与岩相学表现的岩浆混合特征完全吻合,支持岩浆混合成因认识,为解决该岩体成因分歧提供重要依据.     

造山岩套中镁铁质和长英质岩浆的相互作用研究进展

结合2002年9月14—21日在意大利中部召开的“欧洲花岗岩网络”年会的会议讨论和野外考察内容,评述了镁铁质和长英质岩浆的相互作用关系以及镁铁质熔体在巨量花岗岩浆形成中的作用。在花岗岩岩基内,不仅出露有狭义的花岗岩,还可见到更富镁铁质的岩石,例如辉长岩和闪长岩。一般,这些镁铁质岩石,既可能是慢源母岩浆结晶的产物,或是岩浆混合和分异一同化作用中的端员组分,也可能代表了下地壳源区的物质,或者是导致大陆壳部分熔融的热源物质记录。对镁铁质和长英质岩浆相互作用关系的研究,有助于限定造山作用过程中地壳物质再循环和新的地慢物质加入的相对贡献。     

新疆西准噶尔夏尔莆岩体岩浆混合的岩相学证据

夏尔莆岩体由寄主岩石、微粒镁铁质包体和中基性岩墙群组成,具丰富、典型的岩浆混合岩相学特征.野外露头,寄主岩石中暗色矿物分布不均并发育暗色矿物集合体、微小的镁铁质包体和不均匀混合条带;包体具有明显的塑性变形,与寄主岩石或界线截然或渐变过渡,常发育反向脉和寄主岩石中的长石巨晶(捕虏晶);中基性岩墙群与微粒镁铁质包体紧密共生并延伸方向基本一致,发育寄主岩石中的长石捕虏晶,被寄主岩的反向脉横切.在镜下,包体与寄主岩混合带中均发育斜长石异常环带和多种不平衡矿物共生现象,包体中发育针状磷灰石.这些特征表明镁铁质包体和中基性岩墙群来源于与寄主岩石同一岩浆事件的基性岩浆,并与其发生了强烈的岩浆混合作用.岩相学特征为夏尔莆岩体岩浆混合成因提供了重要佐证.     

埃达克质岩的构造背景与岩石组合

本文介绍了埃达克质岩形成的构造背景与岩石组合。埃达克质岩可以形成于不同的构造背景并与不同类型的岩石同时出现：1）火山弧环境中常出现埃达克质岩一高镁安山岩-富Nb玄武质岩组合,它的形成可能与板片熔融以及熔体一地幔橄榄岩的相互作用有关;2）大陆活动碰撞造山带环境（如羌塘）中埃达克质岩常与同期钾质或橄榄玄粗质岩共生,这可能与俯冲陆壳熔融和俯冲陆壳熔体交代的地幔橄榄岩熔融有关;3）造山带伸展垮塌环境（如大别山）中埃达克质岩会伴随有镁铁质一超镁铁质岩浆出露,增厚下地壳产生埃达克质岩浆后的榴辉岩质残留体拆沉进入地幔,与地幔橄榄岩的混合可能形成后期镁铁质一超镁铁质岩浆的源区;4）大陆板内伸展环境中埃达克质岩常与同期橄榄玄粗质的岩石共生,增厚、拆沉下地壳,以及富集地幔的熔融或岩浆混合在岩石的成因中发挥了重要作用。     

南岭东段燕山期镁铁质岩石Nd-Sr同位素研究

南岭东段燕山期镁铁质岩浆活动可划分为四个阶段(中侏罗世、晚侏罗世、早白垩世和晚白垩世)，分别对应四次重要的伸展拉张作用时期。镁铁质岩石具有基本类似的Nd-Sr同位素特征，ISr较高(一般介于0．705～0．710之间)，ENd值变化范围较大(介于-7．90～5．16之间)，表明其岩浆源为壳一幔混合源性质。镁铁质岩石具有板内拉斑玄武岩特征，形成于板内拉张环境，表明该区在燕山早期的中侏罗世即已进入后造山演化阶段。岩石的成因模式为地幔镁铁质岩浆在上升至地壳底部过程中，受到地壳组分的混染，在岩石圈伸展的深部背景和浅部拉张状态下形成。本区燕山期岩浆作用主要是与地幔岩浆底侵作用有关的岩浆事件。     

一种岩浆混合作用的分类及其地质意义:以西昆仑山的3个岩体为例

文章以西昆仑山3个花岗质深成侵入体的研究为例,认为岩浆混合形成的深成岩特征取决于发生混合作用(hybridization)的岩浆的性质,如温度、黏度、成分等物理与化学条件。岩浆的大多数性质都与温度有关,因此可以以温度为主要指标将岩浆混合作用划分为混合、混杂和注入3种类型,分别对应于高、中、低温度条件。库地北岩体具有均一的外貌特征,岩石学和地球化学特征显示其产生具有幔源与壳源岩浆的贡献,是高温岩浆混合作用(mixing)的产物;胜利桥岩体含有大量镁铁质微粒包体,注入的基性岩浆团与其寄主岩浆作用不完全,是中温岩浆混杂作用(mingling)的典型代表,也是造山带出露最广的岩浆混合成因深成岩类;赛图拉岩体形成"双峰式"岩石组合,同时侵位的镁铁质岩浆和长英质岩浆之间基本上不发生物质交换,是两种低温岩浆相互注入的结果。由于岩浆混合作用是壳幔物质与能量交换的集中体现,混合作用的类型体现了区域地热梯度及其地质过程的强度。因此,区分不同的岩浆混合作用类型对了解岩浆混合作用过程、大地构造背景和壳幔相互作用具有重要意义。     

西准噶尔夏尔莆岩体岩浆混合的地球化学证据

夏尔莆岩体是西准噶尔地区典型的岩浆混合花岗岩体之一,由寄主岩石、微细粒镁铁质包体、中基性岩墙群3部分组成。元素地球化学成分的双扩散和相关度是判别岩浆化学混合的最有效手段之一。寄主岩石和中基性岩墙群的地球化学特征差异明显,具不同的演化特征。微细粒镁铁质包体与寄主岩石之间存在强烈的元素双扩散作用,与中基性岩墙又存在亲缘性,地球化学特征具两者之间的过渡性。初步认为夏尔莆岩体是以寄主岩石为代表的地壳岩浆和以微细粒镁铁质包体和中基性岩墙代表的地幔岩浆之间混合的产物。地球化学显示的岩浆混合信息印证了岩相学揭示的岩浆混合成因,为解决该岩体久存的成因分歧从地球化学角度提供了重要依据。     

华北隆化地区七家南岩体中镁铁质微粒包体的发现与成因——岩相学和地球化学证据

华北北缘隆化地区的七家南岩体英云闪长岩中发育有大量镁铁质微粒包体,为探明其成因,开展了岩相学与地球化学研究。结果表明,塑性外形的包体具有典型的岩浆结构和矿物组合,可见冷凝边和反向脉;广泛出现矿物交换现象与不平衡结构:如"环斑"斜长石、榍石-斜长石眼斑、针状磷灰石、熔蚀状锆石等。镁铁质微粒包体较寄主英云闪长岩贫硅、高钙铝、富镁铁,更富集大离子亲石元素,高场强元素亏损程度稍低。在主微量元素协变图解上,二者往往呈良好线性关系的岩浆混合作用趋势;它们的Mg/(Mg+Fe)与Na/(Na+Ca)值也都表现出岩浆混合作用的特点。因此,七家南岩体中的镁铁质微粒包体是进入到寄主英云闪长质岩浆中的偏基性淬冷团块,即岩浆混合作用的产物。     

铂族元素的地球化学行为及全球主要铂族金属矿床类型

全球铂族金属矿床主要有6种类型,分别为：（1）镁铁质-超镁铁质层状岩体铂族金属矿床;（2）镁铁质-超镁铁质Cu-Ni硫化物矿床伴生的铂族金属矿床;（3）Urals杂岩体型铂族金属矿床;（4）蛇绿岩型铂族金属矿床;（5）与热液相关的铂族金属矿床;(6）外生型铂族金属矿床。除第4类型外其他类型的铂族矿床都具有经济意义。铂族金属矿床的形成主要与幔源岩浆性质及岩浆演化过程密切相关。大规模的幔源岩浆活动及在岩浆演化过程中具有产生硫饱和的条件是形成铂族金属矿床的有利条件,同时岩浆期后的热液作用能使铂族元素迁移并在特定条件下富集,对铂族金属矿床的形成有利。镁铁质-超镁铁质层状侵入体形成铂族金属矿床的有利条件是岩浆分异作用强,并且具有能产生高R因子的环境;镁铁质-超镁铁质Cu-Ni硫化物矿床中形成铂族金属矿床的有利条件是硫化物熔体的结晶分异作用;Urals型杂岩体中,由于岩浆在早期演化过程中硫的不饱和,形成的主要铂族矿物为Pt-Fe、Pt-Ir合金,且主要与铬铁矿共生,在岩浆演化硫饱和阶段可形成富Pd的铂族矿物,且与Cu-Fe-V-Ti-P金属共生;蛇绿岩型杂岩体中,主要形成的铂族矿物为含Ir- 、Os- 、Pt- 的合金或少量硫化物矿物,且主要赋存于铬铁矿中。     

昆仑早古生代造山带研究进展

通过对1999年以来在昆仑山地区开展的1∶25万区域地质调查成果资料的分析,结合前人的研究成果,指出了东、西昆仑经历了早古生代造山作用。依据镁铁质—超镁铁质岩的性质及其产出状态、相伴的沉积、岩浆建造,结合前寒武纪地层的出露情况和变质热事件,将昆仑早古生代造山带分为3个大的构造单元,昆中构造带为早古生代的岩浆弧,北部为由库地-其曼于特-祁漫塔格镁铁质—超镁铁质岩带、滩间山群、奥陶系—志留系未分地层等相关边缘沉积体组成弧后盆地沉积、岩浆建造系统,南部为由柳什塔格-吐木勒克-乌妥镁铁质—超镁铁质岩、纳赤台群、温泉沟群共同组成弧前复理石增生楔杂岩带。     

The terrestrial fauna of the Late Triassic Pant-y-ffynnon Quarry fissures,South Wales,UK and a new species of Clevosaurus (Lepidosauria: Rhynchocephalia)

Pant-y-ffynnon Quarry in South Wales yielded a rich cache of fossils in the early 1950s, including articulated specimens of new species (the small sauropodomorph dinosaur Pantydraco caducus and the crocodylomorph Terrestrisuchus gracilis), but no substantial study of the wider fauna of the Pant-y-ffynnon fissure systems has been published. Here, our overview of existing specimens, a few described but mostly undescribed, as well as freshly processed material, provides a comprehensive picture of the Pant-y-ffynnon palaeo-island of the Late Triassic. This was an island with a relatively impoverished fauna dominated by small clevosaurs (rhynchocephalians), including a new species, Clevosaurus cambrica, described here from a partially articulated specimen and isolated bones. The new species has a dental morphology that is intermediate between the Late Triassic Clevosaurus hudsoni, from Cromhall Quarry to the east, and the younger C. convallis from Pant Quarry to the west, suggesting adaptive radiation of clevosaurs in the palaeo-archipelago. The larger reptiles on the palaeo-island do not exceed 1.5?m in length, including a small carnivorous crocodylomorph, Terrestrisuchus, and a possible example of insular dwarfism in the basal dinosaur Pantydraco.     

Définition d'une limite multicritère ; stratigraphie du passage Campanien–Maastrichtien du site géologique de Tercis (Landes,SW France)Definition of a multi-criteria boundary; stratigraphy of the Campanian–Maastrichtian interval of the geological site at Tercis (Landes,SW France)

Lithostratigraphy, physicochemical stratigraphy, biostratigraphy, and geochronology of the 77–70 Ma old series bracketing the Campanian–Maastrichtian boundary have been investigated by 70 experts. For the first time, direct relationships between macro- and microfossils have been established, as well as direct and indirect relationships between chemo-physical and biostratigraphical tools. A combination of criteria for selecting the boundary level, duration estimates, uncertainties on durations and on the location of biohorizons have been considered; new chronostratigraphic units are proposed. The geological site at Tercis is accepted by the Commission on Stratigraphy as the international reference for the stratigraphy of the studied interval. To cite this article: G.S. Odin, C. R. Geoscience 334 (2002) 409–414.     

The effect of water on accessory phase solubility in subaluminous and peralkaline granitic melts

The solubilities of columbite, tantalite, wolframite, rutile, zircon and hafnon were determined as a function of the water contents in peralkaline and subaluminous granite melts. All experiments were conducted at 1035 °C and 2 kbar and the water contents of the melts ranged from nominally dry to approximately 6 wt.% H₂O. Accessory phase solubilities are not affected by the water content of the peralkaline melt. By contrast, solubilities are affected by the water content of the subaluminous melt, where the solubilities of all the accessory phases examined increase with the water content of the melt, up to 2 wt.% H₂O. At higher water contents, solubilities are nearly constant. It can be concluded that water is not an important control of accessory phase solubility, although the water content will affect diffusivities of components in the melt, thus whether or not accessory phases will be present as restite material. The solubility behaviour in the subaluminous and peralkaline melts supports previous spectroscopic studies, which have observed differences in the coordination of high field strength elements in dry vs. wet subaluminous granitic glasses, but not for peralkaline granitic glasses. Lastly, the fact that wolframite solubility increases with increasing water content in the subaluminous melt suggests that tungsten dissolved as a hexavalent species.     

Quaternary stresses revealed by calcite twinning inversion: insights from observations in the Savonnières underground quarry (eastern France)

Calcite samples were extracted both from the rock matrix and the superficial coating of a karstified fault plane of an underground quarry, located in the eastern border of the Paris basin. The karstification is dated as Quaternary. Analysis of mechanical calcite twinning reveals that only the calcite matrix has also undergone a compression trending WNW that can be attributed to the Mio-Pliocene alpine collision. Both coating and matrix have undergone a strike-slip regime with σ₁ roughly trending north–south, that could correspond to the regional present-day state of stress, a strike-slip compression rather trending NNW, modified by local phenomena. To cite this article: M. Rocher et al., C. R. Geoscience 335 (2003).     

NONMETALS DEPOSITS

正20141520 Bo Ying(Key Laboratory of Metallogeny and Mineral Assessment,MLR,Beijing 100037,China);Liu Chenglin Saline Spring Hydrochemical Characteristics and Indicators for Potassium Exploration in Southwestern and Northern Tarim Basin,Xinjiang(Acta Geoscientica Sinica,ISSN1006-3021,CN11-3474/P,34(5),2013,p.594-602,5 illus.,3 tables,28 refs.)     

MATHEMATICAL GEOLOGY

正20141243Chen Ge(Hangzhou Research Institute of Petroleum Geology,PetroChina,Hangzhou 310023,China);Si Chunsong Study on Sedimentary Numerical Simulation Method of Fan Delta Sand Body(Journal of Geology,     

PROSPECTING EXPLORATION

正20142599Chen Sanming(Guangxi Key Laboratory of Concealed Deposits Exploration,Guilin University of Technology,Guilin541004,China);He Yuzhou Block Model and Reserves Estimation of Panzhihua Iron Deposit Based on 3D Geological Modeling(Journal of Guilin University of Technology,ISSN1674-9057,CN45-1375/N,33(4),2013,p.610-615,9illus.,1table,15refs.)     

STRUCTURAL GEOLOGY

正20140594 Bai Daoyuan(Hunan Institute of Geology Survey,Changsha 410016,China);Zhong Xiang Faults in the Jingzhou Basin and Their Tectonic Settings(Geotectonica et Metallogenia,ISSN1001-1552,CN44-1595/P,37(2),2013,p.173-183,6illus.,59refs.)Key words:basin evolution,tectonic setting,South China In the Upper Paleozoic and Jurassic se-     

STRUCTURAL GEOLOGY

正20141912Cao Hui(State Key Laboratory for Continental Tectonics and Dynamics,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China)Gravitational Collapse and Folding during Orogenesis:A Comparative Study of FIA Trends and Fold Axial Plane Traces(Geology in China,ISSN1000-3657,CN11-1167/P,40(6),2013,p.1818-1828,9illus.,35refs.,with