苏北东海榴辉岩地球化学及原岩成因

苏北东海榴辉岩的原岩为蛇绿岩基性熔岩和堆积镁铁岩。其玄武岩的化学成分相当于洋脊拉斑玄武岩，并富集大离子亲石元素、稀土元素和轻稀土元素，属于Ｅ型洋脊玄武岩。它们形成于扬子古大陆板块北缘苏北－胶南地体与胶北地体间洋盆环境中的局部异常脊，是由富集地幔低程度部分熔融和来自深部岩浆的分离结晶作用而形成，由于俯冲消减作用遭受相对低温高压（超高压）的榴辉岩相变质和强烈破碎，被挤压到东海群下部不同构造层位中，是外来的被肢解的蛇绿岩块。     

胶东变质超镁铁—镁铁质岩石的地球化学特征及地幔源区性质

本文以地球化学方法为研究手段,结合野外宏观地质特征,论述了胶东地区前寒武纪变质建造中超镁铁—镁铁质岩石的地球化学性质及其成因。研究结果表明,该区超镁铁—镁铁质岩石为地幔不同程度熔融的产物,超镁铁质岩石相当于科马提岩类;镁铁质岩石为拉斑玄武岩类,并按橄榄质科马提岩→玄武质科马提岩→拉斑玄武岩演化系列的化学组成表现出连续的变化趋势。 拉斑玄武岩中的微量元素(主要是稀土元素)地球化学特征表明,其形成环境与现代板块构造的典型火山(岛)孤或孤后盆地环境相类似,并反映出地幔源区具有“富集型”地幔的特点,且存在着地幔不均一性。     

云南金平县镁铁-超镁铁岩岩床群的地球化学特征

金平地区的镁铁-超镁铁质岩岩床群侵入在晚泥盆世地层中。岩石类型包括粒玄岩、辉绿岩、辉长岩、橄榄辉玄岩和苦橄岩。岩床群的走向与区域构造方向一致,为北西向延伸。单个岩床的厚度在1-200m之间,较厚的岩床有明显的结晶分异作用。粒玄岩和辉绿岩含相当数量的钛铁矿,称为铁钛玄武岩。化学成分以强烈富Ti为特征,TiO₂含量平均达3.9%.Mg含量通常较低,是拉斑质或碱性玄武岩演化而来的。这种高Ti玄武岩还富Th、Ta、Nb,Th/Ta比值接近1,Zr/Nb比值较低,接近OIB的特征,推测产于板内环境,是地幔柱部分熔融形成的岩浆。金平岩床群中苦橄岩和橄榄辉玄岩(MgO含量在15.1%-23.3%之间)出露的比例相对较多,指示地幔柱部分熔融的温度较高,推测相当于地幔柱尾部的特征。     

苏北东海超镁铁岩初步探讨

在江苏北部东海—赣榆地区,断续出露一套中—深变质岩系,称东海群,其上为海州群不整合覆盖。东海群的原岩形成时代为晚太古代—早元古代。在东海群下部分布区,出露有一系列超镁铁岩块和榴辉岩块。本文重点研究超镁铁岩的岩石学、矿物学和岩石化学等特征,并探讨其原生年龄、原生构造环境和侵位年龄、构造侵位方式及其出露机制。     

大别山北部斜长角闪岩类的地球化学特征及形成构造背影

大别山北部变质镁铁－超镁铁质岩带中斜长角闪岩类的常量,微量稀土元素地球化学特征均表明,它们可划分为二类：Ⅰ类为洋岛型拉斑玄武岩;Ⅱ类为岛弧型玄武岩且其中大多数属钙碱性玄武质安山岩和少数属拉斑玄武岩。     

海南岛蓬莱地区超镁铁岩包体及其寄主玄武岩的研究

蓬莱地区寄主玄武岩为晚第三纪火山喷发的产物,主要岩石为碧玄岩,碱性橄榄玄武岩和橄榄玄武岩,其中含有超镁铁岩包体。寄主玄武岩属碱性系列,是地幔橄榄岩低度部分熔融的产物。超镁铁岩包体具有局部熔融的迹象和弱亏损型地幔岩的特征,推测为上地幔橄榄岩低度部分熔融后的难熔残余。     

苏北东海超镁铁岩研究

苏北东海超镁铁岩分为南、北两带。北带以变质橄榄岩为主，南带以洋壳堆积超镁铁岩为主，是“肢解的蛇绿岩”。推测蛇绿岩形成于中—新元古代扬子古大陆板块北缘苏北—胶南地体与胶北地体间的洋盆环境。变质橄榄岩为高温超高压下原始地幔岩经中等程度熔融后的残余地幔橄榄岩。堆积超镁铁岩是原始地幔岩部分熔融或岩浆结晶分离的产物，富含石榴石，与榴辉岩块伴生，是在中—新元古代由洋壳向南俯冲消减过程中形成的相对低温超高压变质岩。它们遭受强烈破碎，被挤压到东海岩群下部不同构造层位中，成为东海俯冲带混杂岩中的深源岩块。     

新疆东天山黑白山镁铁超镁铁岩地球化学、U-Pb年代学、Hf同位素特征及地质意义

黑白山镁铁超镁铁岩位于新疆中天山地块与觉罗塔格构造带的分界断裂——阿其克库都克大断裂南侧约4 km处.该岩体主要由阳起石化橄榄辉石岩、辉橄岩、辉石岩、蚀变细粒辉长岩组成,对岩体的主微量及稀土元素地球化学特征研究表明,岩体属铁质镁铁超镁铁岩,具低钾拉斑玄武质岩的分异特征;岩石具相对较低SiO2(43.90％～52.80％...     

玉石沟铬铁矿床的成因

玉石沟铬铁矿床产于北祁连蛇绿岩型超镁铁岩中，可分为产于堆积超镁铁岩中的堆积铬铁矿床和产于地幔橄榄岩中的豆荚状铬铁矿床两种类型。堆积铬铁矿床由玄武岩浆分离结晶作用形成，位于辉长岩下约２０ｍ处的纯橄岩或辉石岩中；豆荚状铬铁矿床由地幔岩部分熔融作用形成，产于地幔橄榄岩上部或顶部基性程度最高的纯橄岩或纯橄岩－斜辉辉橄岩杂岩带，位于堆积杂岩下约２００～１７００ｍ范围内。     

大别山毛屋镁铁—超镁铁岩块的原岩与超高压变质作用

毛屋镁铁－超镁铁层状岩体由方辉橄榄岩、橄榄方辉岩、含石榴石方辉岩、石榴二辉岩、石榴透辉岩、榴辉岩、绿辉石岩等不同岩性的岩石组成的变层状堆晶岩。     

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.     

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.)     

GEOCHEMISTRY

正20142002 Wei Hualing(Institute of Geophysical and Geochemical Exploration,Chinese Academy of Geological Sciences,Langfang065000,China);Zhou Guohua Element Content and Mineral Compositions in Different Sizes of Soil in Tongling Area,Anhui Province(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,32(11),2013,p.1861