皖南和赣东北蛇绿岩成因及其构造意义：元素和Sm－Nd同位素制约

本文对扬子块体南缘构造侵位于板溪群（及相应地层）的皖南和赣东北晚元古代蛇绿岩进行了系统的元素和Ｓｍ－Ｎｄ同位素地球化学研究，结果表明两套蛇绿岩具有类似的元素地球化学特征，即二者的火山岩元素地球化学特征均类似于形成于弧后盆地构造环境的拉斑玄武岩。但是，两套蛇绿岩的Ｎｄ同位素组成明显不同。赣东北蛇绿岩具有相当均一的高εＮｄ（Ｔ）值（＋５．５±１．２），表明来源于一较亏损的上地幔源区，并且没有受到明显的较成熟地壳物质的混染。相反，皖南蛇绿岩的εＮｄ（Ｔ）值低，并有较大的变化范围（＋４．５──１．０），并和Ｓｍ／Ｎｄ、Ｎｄ、ＭｇＯ、ＳｉＯ２呈明显的二元混合相关关系，表明蛇绿岩是由亏损幔源岩浆（初始εＮｄ（Ｔ）≈＋５．５）在结晶分异过程中与地壳组分（初始εＮｄ（Ｔ）≈－１）混合形成的。皖南和赣东北蛇绿岩的Ｎｄ同位素和元素地球化学特征以及该地区的同时代花岗岩和火山岩的时空分布特征，可以用华南和扬子元古宙陆－弧－陆碰撞模式来解释。大约在１．０Ｇａ前，扬子和华南块体之间存在一多岛弧洋盆。大陆边缘岛弧和大洋岛弧在扬子块体南缘发育演化。皖南和赣东北蛇绿岩就是在大陆边缘盆地和弧间盆地演化过程中形成的洋壳构造侵位的碎片。该地区Ｉ型     

新疆阿尔曼太蛇绿岩时代的Nd—Sr同位素地质研究

本文通过测定采自新疆阿尔曼太兔子泉一带蛇绿岩的堆晶辉长岩、辉绿岩和安山玢岩，获得Ｓｍ－Ｎｄ等时年龄为５６１±４１Ｍａ，εＮｄ（ｔ）＝６．１，Ｒｂ－Ｓｒ等时年龄为３９２±１７Ｍａ，（８７Ｓｒ／８６Ｓｒ）ｉ＝０．７０４１，前者为蛇绿岩的形成时代，后者为蛇绿岩遭受后期变质作用的时间。札河坝－阿尔曼太蛇绿岩的形成环境可能是古亚洲洋向南俯冲引起的弧后盆地     

赣东北蛇绿岩的离子探针锆石U－Pb年龄及其构造意义

离子探针锆石Ｕ－Ｐｂ年龄分析结果表明，赣东北蛇绿岩套的高度分异岩浆的结晶年龄为９６８±２３Ｍａ。重新计算的蛇绿岩Ｓｍ－Ｎｄ等时线年龄９５５±４４Ｍａ，与锆石Ｕ－Ｐｂ年龄在误差范围内一致。１５个样品的εＮｄ（Ｔ）值（Ｔ＝９７０Ｍａ）为＋４．３－＋６．７，表明蛇绿岩来源于强亏损地幔源。少数样品的Ｓｍ－Ｎｄ体系可能受到后期变质、变形或蚀变作用的影响。结合已发表的４０Ａｒ－３９Ａｒ年龄资料，可以初步确定赣东北晚元古代碰撞带发育的时限为０．９７－０．８０Ｇａ。     

东秦岭松树沟蛇绿岩Sm—Nd同位素年龄的地质意义

东秦岭树沟蛇绿岩主要由变质橄榄岩和变质玄武岩组成。变玄武岩全岩Ｓｍ－Ｎｄ同位素等时年龄为（１０３０±４６（２δ））Ｍａ，ＩＮｄ＝０．５１１６１±５（２δ），εＮＤ（ｔ）＝＋５．７±０．２，代表蛇绿岩中玄武岩的形成年龄。这一年龄的确定，为探讨秦岭区中晚元古代的古构造格局提供了重要的证据。     

北准噶尔洪古勒楞蛇绿岩研究的新进展

通过对洪古勒楞东段蛇绿岩的研究，基本搞清了蛇绿者组合特征及其形成时代，首次指出该区在晚震旦世为广阔大洋环境，为研究准噶尔的大地构造演化提供了证据。依据蛇绿岩与围岩的接触关系，指出了其构造侵位时间为奥陶纪末，而与泥盆系则为断层接触。通过Ｓｍ－Ｎｄ等时线法测年结果确定蛇绿岩形成于６２６±２５Ｍａ。从稀土元素、岩石化学和εＮｄ（Ｔ）＝十８．４等综合分析，蛇绿岩来自亏损地幔岩浆，纯属洋中脊产物。     

扬子地台西缘盐边群玄武质岩石地球化学特征及SHRIMP锆石U-Pb年龄

选择盐边群底部荒田组玄武质岩石(原划为蛇绿岩),通过岩石化学和微量元素地球化学研究,认为盐边群玄武质岩石可能形成于弧后盆地环境;通过SHRIMP锆石U-Pb年代学研究,获得玄武质岩石岩浆结晶年龄为782±53Ma,其形成时代为新元古代。同时获得其中继承性变质锆石年龄为1837±14Ma。变质锆石年龄可能代表扬子地台西缘变质基底年龄,证明扬子地台西缘可能存在古元古代变质基底。     

吉林南部太古代花岗岩Sm—Nd,Rb—Sr同位素年龄测定

吉林南部太古代花岗质岩石经同位素年龄测定，英云闪长质片麻岩类的Ｒｂ－Ｓｒ全岩等时年龄为２４１７±１２１Ｍａ，Ｓｍ－Ｎｄ全岩等时年龄为２４１６±１２７Ｍａ，模式年龄为２８４０Ｍａ；辉石花岗岩类的Ｒｂ－Ｓｒ全岩等时年龄为２３４６±２３２Ｍａ，Ｓｍ－Ｎｄ全岩等时年龄为２４４０±１５９Ｍａ，模式年龄为２７８０Ｍａ。反映这些岩石都是在太古宙晚期形成的，并且是在较短的时间间隔内完成的，其模式年龄与华北地台太古宙主体地壳的形成时代一致。     

辽宁清原变质镁铁质火山岩Sm－Nd同位素年龄及其地质意义

在辽宁清原浑南群变质镁铁质火山岩中首次获得的Ｓｍ－Ｎｄ全岩等时线年龄为３０１８±１１０Ｍａ，证实了本区中太古代表壳岩的存在。浑南群为高角闪岩相至麻粒岩相。变质镁铁质火山岩的原岩相当于ＴＨ１型拉斑玄武岩，稀土配分为轻稀土亏损型模式。岩石的εＮｄ（ｔ）值为＋０．１９±０．１７，物源来自亏损相对较小的地幔。     

北秦岭古聚会带壳幔再循环

以同构造期代表古洋壳残片的蛇绿岩及产于古岛弧的玄武岩为基础，通过Ｎｄ，Ｐｂ同位素与微量元素示踪及岩浆源区分析，揭示出北秦岭元古宙上地幔以强亏损（εＮｄ（ｔ）＋６．３～＋７．３）和高的Ｙｂ／Ｈｆ，Ｎｂ／Ｌａ和Ｔｈ／Ｌａ比值为特征，北秦岭地壳和上地幔明显具有Ｐｂ同位素比值高的特征．北秦岭丹凤群岛弧火山岩、二郎坪群弧后玄武岩以及松树沟蛇绿岩中变拉斑玄武岩εＮｄ（ｔ）、放射成因Ｐｂ同位素、Ｙ／Ｔｂ和Ｔｉ－ＭｇＯ研究表明，本区玄武岩存在两类性质不同的岩浆源．一类与亏损的北秦岭岩石圈上地幔源区有关；另一类与携带海洋沉积物的洋壳板块俯冲参与有关．由此，论证了北秦岭古聚会带壳幔之间物质再循环     

新疆西准噶尔蛇绿岩形成时代和环境的探讨

西准噶尔位于西伯利亚,哈萨克斯坦和塔里木3个大陆板块的交汇处,其间存在着不同时代的洋壳残片,有晚寒武世—中奥陶世(523.2±7.2—489±53Ma)形成的夏坦河—唐巴勒蛇绿岩带,有志留纪和泥盆纪—早石炭世(395±1.2Ma)形成的玛依拉和达拉布特蛇绿岩带,有奥陶纪(444±27Ma)形成的洪古勒楞蛇绿岩带。按其岩石组合及地球化学特征可分为两种类型,即唐巴勒和洪古勒楞两类。前着代表弧后盆地拉张的产物,后者是在洋脊环境下形成的。从其分布大致可以反映出西准噶尔古生代洋盆不断向大陆俯冲的痕迹。     

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).     

HYDROGEOLOGY

正20141756 Chen Ruige(Mathematical College,China University of Geosciences,Beijing100083,China);Zhou Xun Numerical Simulation of Groundwater Level Fluctuation in a Coastal Confined Aquifer with Sloping Initial Groundwater Level Induced by the Tide(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,32(7),2013,p.1099-1104,6 illus.,16 refs.) Key words:confined water,groundwater level     

METAMORPHIC PETROLOGY

正20141408 Cai Jia(Institute of Geology,Chinese Academy of Geological Sciences,Beijing100037,China);Liu Fulai Petrogenesis and Metamorphic P-T Conditions of Garnet-Spinel-Biotitebearing Paragneiss in Danangou Area,Daqingshan-Wulashan Metamorphic Complex Belt(Acta Petrologica Sinica,ISSN1000-0569,CN11-1922/P,29(7),     

SERIALS

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GEOPHYSICAL EXPLORATION

正20142386An Guoying(China Aero Geophysical Survey and Remote Sensing Center for Land and Resources,Beijing 100083,China)Application of Satellite Remote Sensing in Regional Hydrogeological Investigation:Taking Cenozoic Strata in Wenquan Sheet(1∶250 000)of Karakoram Range as an Example(Geosci-     

QUATERNARY GEOLOGY & GEOMORPHOLOGY

正20141016An Chengbang(Key Laboratory of Western China’s Environmental Systems,Ministry of Education,Lanzhou University,Lanzhou 730000,China);Zhao Yongtao Lake Records during the Last Glacial Maximum from Xinjiang,NW China and Their Climatic Impli-     

PETROLEUM GEOLOGY

正20141538 Cao Qing(School of Earth Sciences and Engineering,Xi’an Petroleum University,Xi’an 710065,China);Zhao Jingzhou Characteristics and Significance of Fluid Inclusions from Majiagou Formation,Yichuan Huangling Area,Ordos Basin(Advances in Earth Science,ISSN1001-8166,CN62-1091/P,28(7),2013,p.819-828,7 illus.,3 tables,43 refs.)