新疆北山石炭纪、二叠纪火山岩岩石化学及构造环境分析

北山地区火山岩发育,以熔岩和凝灰岩为主。空间上呈线性分布,岩性组合为玄武岩、安山岩、流纹岩。成分一般富镁、贫钾,以钙碱性系列为主。岩石指数、微量元素和稀土元素、同位素特征,均表明岩浆来源于上地幔的部分熔融。岩浆上升演化过程中遭受部分混染作用。是造山带岩浆作用产物。     

内蒙锡盟新生代玄武岩的岩石学研究

依照地层顺序和火山机构的完好程度,内蒙锡盟新生代玄武岩可粗略划分为三期。各期玄武岩又可分出若干层(次)。玄武岩由含量不等的橄榄石、单斜辉石和斜长石斑晶及基质组成。部分玄武岩含有二辉橄榄岩等深源包体。斑晶矿物均具有成分环带。矿物化学、岩石化学资料揭示出本区玄武岩从原生岩浆到进化岩浆的主要演化机制是以橄榄石为主的分离结晶作用,同时在部分进化岩浆中还存在岩浆混合作用。稀土元素资料还指出了一个形成本区原生岩浆以及派生岩浆的原生母岩浆的重要机制:上地幔渐进的部分熔融作用。     

煎茶岭与金川硫化镍矿床的铂族元素地球化学特征对比及其意义

采用ICP—MS方法分析了煎茶岭和金川硫化镍矿床岩石、矿石的铂族元素含量,煎茶岭岩体蛇纹岩的Cu／Pd比值低于原生地幔岩浆,说明岩浆熔离作用较弱,矿石的Pd／Ir比值较小,指示其多数矿石属于岩浆型,以岩浆成矿作用为主;而金川岩体的平均Cu／Pd比值远大于原生地幔岩浆,表明岩浆熔离作用强,矿石的Pd／Ir比值较大,体现了钯族元素矿化及成矿物质以幔源为主的特征。煎茶岭在成矿过程中有壳源物质的混染,整体上岩石、矿石铂族元素含量较低,这与岩浆熔离作用弱、铂族元素成矿作用不发育等因素有关;金川在成岩成矿过程中也有少量地壳物质的混染,但岩石、矿石铂族元素含量较高,反映了以岩浆深部熔离成矿作用为主的特征。     

塔里木板块早—中二叠世玄武质岩浆作用的沉积响应

塔里木板块内部发育了大量由早—中二叠世板内岩浆作用所形成的、以玄武岩类为主的基性岩浆岩,包括玄武岩、辉绿岩、玄武安山岩等,残余分布面积约20万km2。而二叠纪时期是塔里木板块演化过程中一个非常重要的转折时期,从早二叠世晚期开始塔里木板块结束了海相沉积,进入了陆相沉积阶段。通过对塔里木板块的岩浆作用特征和石炭纪—二叠纪沉积相的分析,笔者讨论了这一大规模的岩浆作用对板块晚石炭世—二叠纪的沉积作用所起的控制作用,提出了塔里木板块早—中二叠世巨量玄武质岩浆作用的沉积响应过程模式。     

岩浆流体与成矿

科学观测表明在敛聚型和离散型板块边界大量挥发份和金属通过去气作用从乐分离而进入陆相和海底火山－热液系统。以ＣＯ２为主的流体伴随着挥发份贫乏的洋脊型玄武质岩浆作用而形成,其岩浆产生于洋脊之下的地幔的部分熔融过程,与此对照,丰富的以Ｈ２Ｏ为主的流体产生于富含挥发份的火山弧型岩浆的去气这种岩浆的起源与俯冲洋壳的脱水过程有关。岩浆流体常由各种挥发份和含量不等的金属组成。受挥发份在熔体中的溶解度制约,由岩浆     

黑龙江五星铜镍、铂钯矿床镁铁质杂岩的元素地球化学特征与岩石成因

五星超镁铁质- 镁铁质杂岩的元素地球化学特征研究表明, 其原始岩浆为低钛、高镁的拉斑玄武岩浆, 由以CO2 为主的流体交代亏损地幔所形成的弱亏损地幔部分熔融产生, 其残余矿物相主要为石榴石、尖晶石和金红石。岩浆形成与演化经历了3 个阶段: ① 上升的软流圈与岩石圈地幔接触, 热流体作用导致岩石圈地幔发生高度部分熔融, 形成初始硫饱和的次碱性玄武岩; ②初始岩浆上侵, 在下地壳形成岩浆房, 岩浆结晶作用形成以似层状橄榄石、紫苏辉石、普通辉石和磁铁矿等为主的堆晶岩, 在地壳物质的参与下形成残余辉长质岩浆; ③ 岩浆房破裂, 残余岩浆和含有熔体( < 30% ) 的堆晶岩相先后上侵形成五星原始镁铁质杂岩。就铜镍和铂钯矿化而言, 铜镍硫化物形成于岩浆房分离结晶晚期的熔离作用, 而铂钯矿化则主要在成岩期后流体作用阶段形成。     

岩浆矽卡岩铜锌矿床地质特征与成矿机制探讨——以西藏当雄县拉屋铜锌矿床Ⅴ号矿体为例

西藏当雄县拉屋铜锌矿床位于冈底斯—念青唐古拉成矿带江让—伯舒拉岭多金属成矿亚带.从矿体地质特征、稳定同位素、稀土元素、微量元素地球化学特征等方面对其Ⅴ号矿体进行分析,研究后认为其成因应为岩浆矽卡岩型,其机制是深部熔浆在上侵过程中经分异作用,以钾、钠硅酸盐为主的熔浆浮于上部,以钙、镁、铁为主的熔浆(矽卡岩岩浆)沉于下部,从而形成含矿矽卡岩岩浆,进而形成岩浆矽卡岩矿床.     

富碱斑岩成因与Cu—Mo—Au矿床成矿作用——以金沙江—红河富碱斑岩成矿带为例

富碱斑岩因其产出构造环境独特、岩石类型特殊,并常与铜多金属矿床密切相关,而受到广泛关注。本文在回顾相关研究进展的基础上,通过岩石成因和构造环境、岩浆性质和岩浆源区等方面的综合研究,探讨了金沙江—红河富碱斑岩成矿带富碱岩浆成矿作用及成岩成矿机制。系统的矿床地质、年代学、地球化学等研究表明：① 金沙江—红河富碱斑岩成矿带内成岩成矿作用集中于43~32 Ma,成矿富碱斑岩系始新世—渐新世I型钾玄质花岗斑岩,是印—亚大陆后碰撞背景下大陆内部大型走滑和伸展等动力过程诱导的岩浆活动产物,金沙江和哀牢山—红河断裂的差异走滑运动可能控制了成矿带差异性成岩成矿事件;② 成矿带北段以Cu—Mo为主的成矿富碱斑岩源自新元古代下地壳的部分熔融,且源区有富集地幔和亏损地幔物质的加入,而南段以Cu—Au或Cu(—Mo—Au)为主的成矿富碱斑岩源自具有不同程度富集地幔物质加入的新生下地壳的部分熔融;③ 带内以Cu为主的斑岩—矽卡岩型矿床中成矿富碱斑岩的氧逸度（ΔFMQ）与矿床规模具有正相关性。除受氧逸度控制外,源区高K2O含量有利于斑岩—矽卡岩型Au矿床的形成。该研究对金沙江—红河富碱斑岩成矿带乃至同类矿床研究和找矿勘查具有理论和实际意义。     

内蒙东部红花沟金矿田早中生代构造-岩浆活动及对金成矿的控制作用

根据红花沟金矿田早中生代的韧性变形带、闪长质岩浆岩和中基性岩墙群的特点 ,提出早中生代时研究区总体上处于伸展隆升状态 ,并可细分为两个阶段 ,早阶段以韧性变形为主 ,晚阶段以闪长质岩浆活动为主。闪长质岩浆是在地幔热隆起构造背景下 ,地幔底侵作用引起太古界变质岩中的基性岩石发生部分熔融而形成的。早中生代的构造 -岩浆活动为金成矿提供了流体和成矿物质来源及容矿空间 ,金成矿主要与早中生代的构造 -岩浆作用有关。     

富碱斑岩成因与Cu—Mo—Au矿床成矿作用——以金沙江—红河富碱斑岩成矿带为例

富碱斑岩因其产出构造环境独特、岩石类型特殊,并常与铜多金属矿床密切相关,而受到广泛关注。笔者等在回顾相关研究进展的基础上,通过岩石成因和构造环境、岩浆性质和岩浆源区等方面的综合研究,探讨了金沙江—红河富碱斑岩成矿带富碱岩浆成矿作用及成岩成矿机制。系统的矿床地质、年代学、地球化学等研究表明：(1)金沙江—红河富碱斑岩成矿带内成岩成矿作用集中于43～32 Ma,成矿富碱斑岩系始新世—渐新世I型钾玄质花岗斑岩,是印—亚大陆后碰撞背景下大陆内部大型走滑和伸展等动力过程诱导的岩浆活动产物,金沙江和哀牢山—红河断裂的差异走滑运动可能控制了成矿带差异性成岩成矿事件;(2)成矿带北段以Cu—Mo为主的成矿富碱斑岩源自新元古代下地壳的部分熔融,且源区有富集地幔和亏损地幔物质的加入,而南段以Cu—Au或Cu(—Mo—Au)为主的成矿富碱斑岩源自具有不同程度富集地幔物质加入的新生下地壳的部分熔融;(3)带内以Cu为主的斑岩—矽卡岩型矿床中成矿富碱斑岩的氧逸度(ΔFMQ)与矿床规模具有正相关性。除受氧逸度控制外,源区高K₂O含量有利于斑岩—矽卡岩型Au矿床的形成。该研究对金沙江—红河富碱...     

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