内蒙古赤峰鸡冠山含钼矿杂岩体的地球化学特征

鸡冠山斑岩型钼矿床是西拉木伦钼矿带上最近发现的重要大型钼矿床之一。本文通过对鸡冠山斑岩型钼矿床赋矿岩石的岩相学及地球化学特征研究,确定了这些岩石的岩性主要为花岗斑岩、流纹岩、流纹斑岩、粗面岩、粗面斑岩及辉绿岩,主要属于高钾钙碱性系列及钾玄岩系列,为准铝质-过铝质岩石。样品稀土元素表现为轻稀土富集的配分模式,LREE/HREE变化于3.94~7.87,(La/Yb)N介于3.59~8.19,除了辉绿岩之外均具有铕(Eu)元素亏损的特点(δEu=0.10~0.68)。微量元素原始地幔标准化图解表现出富集大离子亲石元素亏损高场强元素的特征。根据赋矿围岩的地球化学特征,推测中酸性岩岩浆源区为地壳,岩浆演化过程中可能经历了磷灰石、黑云母和斜长石的分离结晶作用,或分异出富含挥发分的P元素的热液,揭示该矿床是在燕山运动强挤压期后的伸展环境下形成的,是亚洲东部大陆地壳的"蠕散"和"伸展"的结果。     

河北丰宁撒岱沟门钼矿区成矿岩体地球化学特征及其对矿床成因的约束

本文通过对撒岱沟门钼矿床的赋矿岩石(二长花岗岩)的主量元素地球化学的研究,揭示了该区花岗岩为准铝质高钾钙碱性I型花岗岩。该区赋矿岩石(二长花岗岩)的稀土元素地球化学特征为轻稀土富集,重稀土亏损,轻重稀土分馏明显,Eu负异常较弱(δEu=0.78)。La/Sm-La图解表明二长花岗岩由岩浆分离结晶作用形成;微量元素Nb、Ta、P、Zr、Ti具有明显的负异常,富集大离子亲石元素Rb、Th、K、Ba,黑云母全铝压力计所计算的岩体结晶压力平均为1.83kbar,平均侵位深度为6.78km,综合地球化学各方面的特征,探讨了该区斑岩型Mo矿床形成的制约因素,以及为什么该区形成斑岩型钼矿床而非斑岩型铜矿床的原因,最后认为该矿床为深源中成斑岩型钼矿床。     

内蒙古额尔古纳乌尔根矿田富碱斑岩体成因及构造启示:地质年代学和地球化学证据

乌尔根矿田主要由东珺浅成热液型银铅锌矿床和大加布果斯斑岩型钼矿床组成。野外地质调查揭示富碱斑岩岩浆热事件与浅成热液型银铅锌矿床时空关系密切,获得成矿期正长斑岩和成矿前石英二长斑岩锆石U-Pb年龄分别为125Ma和165 Ma。鉴于大加布果斯斑岩型钼矿床成矿时代为147 Ma,而东珺银铅锌矿床成矿作用发生在早白垩世,进而得出两者为相对独立成矿体系。岩石地球化学特征表明,正长斑岩和石英二长斑岩属偏铝质钾玄岩系列,与A型花岗岩特征相似。岩石富集大离子亲石元素(LILE)和轻稀土元素(LREE),亏损高场强元素(HFSE)和重稀土元素(HREE),Eu异常不显著(Eu/Eu^*=0.65～0.83),表明岩浆源自富集型岩石圈地幔的部分熔融,经历了分异结晶并遭受有限的地壳混染;暗示矿田岩浆-成矿作用与洋壳俯冲有关,结合区域地质背景和矿田相关研究认为中侏罗世矿田处于弧后引张环境,而晚侏罗世-早白垩世处于蒙古-鄂霍次克洋闭合之后的伸展环境。     

新疆富蕴地区希勒库都克铜钼矿床含矿斑岩的年代学与地球化学特征

位于新疆富蕴县境内的希勒库都克铜钼矿属于斑岩型矿床。含矿花岗斑岩和石英闪长岩为弱过铝质高钾钙碱性岩石,具有相对富集大离子亲石元素、亏损Nb、Ta、Ti元素的地球化学特征。获得含矿花岗斑岩SIMS锆石Ｕ-Pb年龄（329.6±4.1）Ma。综合分析,花岗斑岩和石英闪长岩可能为同一岩浆不同演化阶段的产物。据含矿岩石高的正εNd（t）值、低的87Sr/86Sr初始值推测,其原始岩浆起源于亏损地幔源区。     

蒙古国阿林诺尔钼矿床赋矿花岗岩年代学及地球化学特征

蒙古国阿林诺尔钼矿床赋存于细粒黑云母花岗岩体中, 整体呈平卧的柱状大矿体, 矿床蚀变发育。本文报道了该矿床赋矿花岗岩SHRIMP锆石U-Pb年龄, 并对其进行了元素地球化学研究。SHRIMP锆石U-Pb年代学研究表明, 阿林诺尔赋矿花岗岩侵位于229.0 ± 2.2 Ma(MSWD=1.16), 为中三叠世, 与他人测定该矿床辉钼矿Re-Os等时线年龄(227±3.1 Ma, MSWD=0.07)在误差范围内一致, 表明矿床与赋矿花岗岩体的岩浆作用有着密切的成因联系, 成岩成矿的年龄也与该区蒙古?鄂霍次克残余洋盆消减作用处于同一时期。元素地球化学研究显示, 岩体具有过铝质高钾钙碱性特征, 富集Rb、Ba、Th以及K等大离子亲石元素, 亏损Nb、Ta以及Ti等高场强元素, 具有Climax型斑岩钼矿的特征, 其形成过程可能与俯冲板块上方地壳伸展作用过程中高钾钙碱性岩浆活动有明显的联系。阿林诺尔钼矿赋矿岩体的成岩成矿作用是蒙古?鄂霍次克残余洋盆向两侧大陆俯冲构造体制下地壳伸展作用的产物。     

江西东乡花岗斑岩LA-ICP-MS锆石U-Pb年龄、地球化学特征及其地质意义

通过对东乡铜矿花岗斑岩进行岩石地球化学特征、锆石U-Pb定年研究,探讨其岩石成因、构造环境、形成时代与成矿的关系。东乡花岗斑岩的LA-ICP-MS锆石U-Pb年龄为156.4±1.5~161±1.0Ma。该岩体为高钾钙碱性系列,轻稀土元素富集,重稀土元素较亏损,具有明显的负Eu异常。微量元素富集大离子亲石元素,而亏损高场强元素。地球化学特征表明,东乡岩体形成于碰撞构造环境,岩浆来源于地幔,但形成演化期间经历了地壳物质的同化混染。该区矿石与花岗斑岩的稀土元素配分曲线存在一定的相似性,且成矿时间与岩浆侵入时间相近,表明岩浆侵入对东乡铜矿床的形成具有重要贡献。     

滇西北格咱岛弧带南缘铜厂沟斑岩铜钼矿床花岗闪长斑岩地球化学特征、锆石U-Pb年龄及其地质意义

云南格咱岛弧构造-岩浆成矿带是义敦岛弧的重要组成部分,属于西南三江地区铜多金属矿床富集区之一。对格咱岛弧南缘铜厂沟成矿斑岩的岩石学、地球化学特征及锆石U-Pb年龄进行了研究,系统分析了区内花岗岩的岩石成因、形成的构造环境及成岩成矿的地球动力学背景。铜厂沟成矿斑岩主要为花岗闪长斑岩,用LA-ICP-MS测得其中锆石的~(206)Pb/~(238)U年龄为87.62±0.59Ma。岩石地球化学特征表明,铜厂沟花岗闪长斑岩具有高硅、富碱、富钾的特点,属于高钾钙碱性岩石系列;岩石具有较高的稀土元素总量;富集轻稀土元素,轻、重稀土元素分馏明显,δEu为0.89~0.97,具较弱的负异常;微量元素特征表明,岩石富集大离子亲石元素K、U、Th、Rb、Ba、Sr,亏损高场强元素Nb、Ta、P、Ti;大离子亲石元素的富集和Nb、Ta等高场强元素的亏损,说明岩浆主要来源于壳源物质的部分熔融。本区花岗岩形成于碰撞后与伸展构造的转换阶段,属于碰撞造山过程的产物。碰撞诱发的岩石圈地幔物质上涌导致地壳发生部分熔融作用,形成富钾的初始含矿岩浆,岩浆沿深大断裂上升侵位最终形成了格咱岛弧燕山晚期的构造-岩浆作用及成矿事件。     

大兴安岭大洋山钼矿成矿岩体地球化学、锆石U-Pb年龄及构造背景

大洋山斑岩型钼矿位于大兴安岭东北部呼中区,钼矿体主要产于石英二长斑岩体和上盘围岩中,产状受石英二长斑岩体控制。通过锆石LA-ICP-MS U-Pb定年,获得石英二长斑岩年龄为(119.83±0.87) Ma,可代表成矿年龄。岩石地球化学数据显示岩体偏铝、贫钛、富钾,具钾玄岩特征,为造山带岩石,岩浆熔体未与地幔相互作用;相对富集大离子亲石元素Rb和K,相对亏损高场强元素Nb、Ta、P、Ti和HREE,亲地幔元素亏损、轻稀土富集以及Eu中等亏损等特征显示岩浆源自陆壳。结合区域地质资料认为大洋山斑岩型钼矿形成于早白垩世晚期,成矿物质来源为地壳的重熔,与蒙古—鄂霍茨克洋的俯冲闭合相关,成矿环境为伸展构造背景。     

东秦岭金堆城大型斑岩钼矿床同位素及元素地球化学研究

文章系统研究了金堆城钼矿床的含矿钾长斑岩、围岩、矿石、矿石中的黄铁矿及矿化围岩的地球化学特征,深入探讨了矿区成矿物质的来源.金堆城含矿斑岩的稀土元素分布和特征地球化学参数显示,金堆城含矿斑岩富集LREE(LaN/YbN=540～1684),轻、重稀土元素分馏较明显,Eu异常不明显或无Eu异常(δEu=070～096).矿石中黄铁矿富集LREE(LaN/YbN=315～2628),具有弱的Eu负异常,无Ce异常(δEu=064～081, δCe=088～103),并与金堆城含矿钾长斑岩和矿石具有一致的球粒陨石标准化配分曲线和特征的地球化学参数,显示金堆城钼矿床的成矿物质来源与钾长斑岩同源.矿床铅、硫、碳和氢-氧同位素地球化学综合研究表明,成矿物质来源于深部,与钾长斑岩同源.围岩在矿化和蚀变过程中元素的迁移计算结果表明,在热液成矿过程中Mo随成矿流体加入到围岩并使围岩发生蚀变和矿化.钼矿床的成矿物质主要来自钾长斑岩,围岩不提供成矿物质.金堆城含矿斑岩和钼矿化的发生处于秦岭造山带在中新生代的挤压-伸展转变期,受板片断离作用和壳幔边界附近发生的基性岩浆底侵作用影响,加厚的华北地块南缘下地壳物质发生熔融形成花岗质岩浆,并沿构造薄弱带上升到浅部侵位,形成金堆城等同熔型斑岩和斑岩型矿床.     

内蒙古新巴尔虎右旗特格乌拉地区花岗斑岩年代学及地球化学特征

对大兴安岭特格乌拉地区花岗斑岩进行岩石学、地球化学、成因及构造环境研究结果显示，花岗斑岩年龄为145.9±1.2 Ma，形成时代为早白垩世晚期.岩石具有富硅、富碱和富铝质的特点，属于准铝质-铝质高钾钙碱性系列.矿物组合及地球化学特征显示特格乌拉地区花岗斑岩为高分异I型花岗岩，富集大离子亲石元素（Rb、Th、U）和轻稀土元素（La、Ce、Pr），负Eu异常明显，显示壳源岩浆或岩浆被地壳物质混染的地球化学特点.特格乌拉地区花岗斑岩形成于造山后伸展环境，这种构造背景可能与蒙古-鄂霍次克缝合带闭合后加厚陆壳的拆沉作用有关.     

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.)