燕辽成矿带养马甸斑岩型钼矿成矿岩体的年代学、地球化学及成岩成矿环境

养马甸钼矿床位于燕辽钼(铜)成矿带东段的辽西地区。养马甸岩体由似斑状花岗岩、粗粒花岗岩和细粒花岗岩3个不同岩相组成,主要矿物为石英(30%～45%)、钾长石(35%～50%)、斜长石(15%～25%)和少量黑云母(3%～5%)。矿体主要赋存于养马甸岩体的细粒花岗岩中,少部分赋存在紧邻细粒花岗岩的粗粒花岗岩和似斑状花岗岩中。地球化学研究表明,养马甸岩体总体为富硅(w(SiO2)=69.26%～76.44%)、富碱(w(Na2O+K2O)=7.87%～8.81%),贫钙(w(CaO)=0.36%～1.33%)、镁(w(MgO)=0.17%～0.61%)和铁(w(FeOT)=1.47%～3.39%)的钾质(K2O/Na2O=1.05～1.31)—准铝质花岗岩(A/CNK=0.90～1.00)。该岩体总体富集大离子亲石元素(K、Rb、Th和LREE),高场强元素(Nb、Ta、Zr、Hf和HREE)亏损不明显,而中稀土相对亏损,在稀土元素配分图上呈左陡右缓的"V"型。岩石地球化学及矿物演化特征表明,养马甸岩体的不同岩相为同源岩浆经历不同程度分离结晶作用的产物,其母岩浆来源于高压麻粒岩相下地壳物质的部分熔融。成岩与成矿年代学研究表明,似斑状花岗岩的LA-ICP-MS锆石U-Pb年龄为(192.1±1.9)Ma,粗粒花岗岩的LA-ICP-MS锆石U-Pb年龄为(189.5±1.4)Ma,而细粒花岗岩的LA-ICP-MS锆石U-Pb年龄为(189.3±3.3)Ma。结合对已有资料的归纳和分析,认为养马甸斑岩钼矿形成于后造山背景下的陆内伸展环境,含矿岩体及斑岩型钼矿的形成可能与古亚洲洋残留地幔楔在早侏罗世的再活化有关。     

南秦岭桂林沟斑岩型钼矿Re-Os同位素年代学及其构造意义研究

陕西省镇安县桂林沟斑岩型钼矿床位于南秦岭多金属成矿带内,其成矿围岩主要为细粒花岗岩、钾长花岗岩和蚀变的粗粒花岗岩。本文通过对桂林沟斑岩型钼矿床中辉钼矿Re-Os同位素定年以及围岩中锆石U-Pb年代学研究,旨在探讨成矿成岩的关系及其构造意义。结果表明,6件辉钼矿的Re-Os同位素年龄在195.9~198.5Ma之间,加权平均年龄为197.2±1.3Ma,表明桂林沟钼矿形成于早侏罗世。围岩细粒花岗岩、钾长花岗岩和粗粒花岗岩的锆石U-Pb年龄分别为199±1.4Ma、201±3.1Ma和198±11Ma,这说明其成岩和成矿年龄基本一致。值得注意的的是,桂林沟钼矿床的形成年龄不同于前人已报导的秦岭钼矿的三个主要成矿期,即238~213Ma、145~126Ma和116~110Ma,其稍晚于第一成矿期。200~190Ma可能代表了秦岭成矿带一期尚未认识的重要成矿事件,对于南秦岭找矿具有重要意义。该期钼矿形成于秦岭印支期碰撞之后,是在造山带垮塌引起的岩浆-热液事件过程中形成的。     

内蒙古丰镇市泉子沟斑岩钼矿床成岩成矿年代学及其地质意义

泉子沟斑岩钼矿床位于内蒙古丰镇市,地处华北克拉通北缘内蒙古台隆凉城断隆内。矿区出露一套燕山期花岗质杂岩体——红娘山杂岩体,主要由中粗粒花岗岩、似斑状花岗岩和石英斑岩组成,钼矿体主要赋存于似斑状花岗岩中。文章在详细的野外地质调查基础上,对泉子沟矿床的成岩成矿时代进行了详细研究,并探讨了地质意义。5件辉钼矿样品的Re-Os模式年龄介于(158.8±2.2)Ma~(161.5±2.2)Ma之间,其加权平均值为(159.8±1.0)Ma(MSWD=0.92),等时线年龄为(161.7±3.1)Ma(MSWD=1.40)。红娘山杂岩体LA-ICP-MS锆石U-Pb年龄分别为:中粗粒花岗岩结晶年龄为(173±1)Ma(MSWD=0.88),似斑状花岗岩侵位年龄为(162±1)Ma(MSWD=0.40),石英斑岩结晶年龄为(160±2)Ma(MSWD=1.90)。辉钼矿Re-Os和锆石U-Pb定年结果表明,泉子沟钼矿床形成于晚侏罗世早期,成矿与似斑状花岗岩关系密切。泉子沟钼矿床的辉钼矿w(Re)介于16.49×10~(-6)~32.87×10~(-6),暗示成矿物质主要来自下地壳。     

江西富城岩体西部过铝质细粒花岗岩锆石U-Pb年龄和地球化学特征

针对江西会昌富城岩体年代学的不同结论,对该岩体西部的细粒花岗岩进行了锆石U-Pb 年代学研究,并分析了细
粒花岗岩和粗粒花岗岩的岩石地球化学和锆石Hf 同位素地球化学特征,探讨了该岩体的成因和构造背景。细粒花岗岩LAICP-
MS 锆石U-Pb 定年结果表明,成岩年龄为219.1~221.5 Ma（平均220 Ma）,为印支期岩浆活动产物;岩石地球化学组成
上表现为高硅（SiO2=71.7%~78.2%）、富碱（K2O+Na2O=7.16%~8.13%,K2O/Na2O=2.00~3.53）、强过铝（A/CNK=1.11~1.26）,贫Ca,Mg; 稀土元素总量较低（ΣREE=72.9×10-6~203.0×10-6),Eu 负亏损强烈, 富集Rb,Cs,K,Pb等大离子亲石元素和Th,U,Ta,Zr等高场强元素,贫Ba,Sr,P,Ti 等元素;综合岩相学和岩石地球化学特征表明该岩体为S型花岗岩。粗粒花岗岩定年结果表明,成岩年龄为227 Ma,也为印支期岩浆活动的产物;岩石地球化学组成上同样表现为高硅
（SiO2=75.1%~76.3%）、富碱（K2O+Na2O=7.39%~8.72%,K2O/Na2O=1.79~2.60）、弱过铝到强过铝（A/CNK=0.9~1.14）,贫Ca,Mg。稀土元素总量较低（ΣREE=125.5×10-6~160.2×10-6）,Eu负亏损强烈,富集Rb,Cs,K,Pb 等大离子亲石元素和Th,U,Ta,Zr 等高场强元素,贫Ba,Sr,P,Ti 等元素;综合岩相学和岩石地球化学特征表明该岩体为S 型花岗岩。同位素组成方面,富城细粒花岗岩体的εHf（t ）值变化于-2.3~-10.8 之间,平均为-7.5,两阶段模式年龄为1.4~1.96 Ga,粗粒花岗岩体的εHf（t ）值变化于-5.0~-19.8之间,平均为-8.8,两阶段模式年龄为1.59~2.51 Ga,表明源岩为元古代壳源富泥质变质组分经过部分熔融,再经过分离结晶作用,在同碰撞构造背景下形成了富城细粒花岗岩和粗粒花岗岩。     

辽宁鞍山地区东山杂岩带3.3～3.1Ga期间的岩浆作用——锆石SHRIMP U-Pb定年

报道了鞍山地区东山杂岩带奥长花岗岩和二长花岗岩的锆石SHRIMP U-Pb年龄。中粗粒奥长花岗岩中岩浆锆石的年龄为3329Ma±22Ma（MSWD=9.6）,存在年龄为3687~3784Ma的残余锆石。细粒奥长花岗岩和二长花岗岩中岩浆锆石的年龄分别为3141Ma±8Ma（MSWD=1.5）和3142Ma±5Ma（MSWD=0.35）。表明约3.3Ga和3.1Ga是鞍山地区2个重要的地壳演化阶段。     

粤北白沙岩体早白垩世细粒花岗岩年代学、地球化学特征及成因意义

粤北佛冈岩体北缘的白沙岩体细粒黑云母二长花岗岩LA-ICP-MS锆石U-Pb加权平均年龄为130.3±3.0Ma,表明细粒黑云母二长花岗岩侵入于早白垩世。岩体高硅(SiO2=70.64~75.01wt%),高Na2O+K2O(7.62~8.33wt%),低P2O5(0.024~0.100wt%),富集Rb、Th、U、K、Pb、Nd、Zr和Hf等元素,亏损Ba、Nb、Ta、La、Ce、Sr、P和Ti等。明显富集轻稀土元素[(La/Yb)N=6.74~54.69],显示明显的负Eu异常(δEu=0.15~0.35),少量正Eu异常(δEu=0.82~1.19)。这些地球化学特征指示细粒黑云母二长花岗岩为高分异I型花岗岩。锆石Hf同位素研究结果表明,εHf(t)=-7.3^-10.6,其平均值为-8.89。其两阶段模式年龄(T2DM)主要为1654~1865Ma(n=8),平均值为1751Ma。佛冈复式岩体早白垩世细粒黑云母二长花岗岩形成于古太平洋板块向欧亚板块俯冲的陆缘弧构造背景下,其地球化学特征表明其物质主要来源于古元古代地壳的杂砂-泥质源岩部分熔融,并有少量幔源物质参与。     

北秦岭马河钼矿区花岗岩类的锆石U-Pb年龄、地球化学特征及其地质意义

本文对北秦岭马河钼矿区桃官坪中-细粒二长花岗岩和西沟斑状二长花岗岩进行了LA-ICP-MS锆石U-Pb年龄测定,分别获得了157±1Ma(NSWD=13)和153±1Ma(NSWD=14)的谐和年龄,表明其为晚侏罗世侵入体。马河钼矿的形成与这两个侵入体密切相关,据此限定该钼矿床成矿时代略晚于157~153Ma,为侏罗世晚期成矿。桃官坪和西沟花岗岩具有高硅(68.12%~76.33%),富碱(Na₂O+K₂O=6.35%~10.38%)的特征,K₂O/Na₂O变化较大(0.91~1.89),A/CNK在0.85~1.14之间,为准铝质-弱过铝质高钾钙碱性系列。微量元素上富集U、Pb、Hf等高场强元素,亏损Rb、Ba、K、Sr、P等大离子亲石元素。稀土元素配分曲线为轻稀土相对富集的右倾型,多数具有弱的负铕异常(δEu=0.5~0.9),少数样品具有弱正铕异常(δEu=1.05~1.08)。与华北地块南缘与钼矿有关的花岗岩相比,二者均具有高硅、高钾、富碱的特征。但马河钼矿区成矿花岗岩比华北地块南缘的稍基性,这可能是导致马河钼矿的矿床规模比华北地块南缘较小的原因之一。     

辽东宽甸东北沟钼矿二长花岗岩年代学、地球化学及Hf同位素特征

东北沟钼矿是辽宁宽甸地区近些年发现的大型隐爆角砾岩型钼矿床。文章首次对东北沟钼矿床赋矿围岩二长花岗岩进行LA-MC-ICP-MS锆石U-Pb定年,主量元素、微量元素和Hf同位素地球化学研究,锆石U-Pb定年结果表明,二长花岗岩形成年龄为(129.4±0.3)Ma(MSWD=0.83),为燕山期构造岩浆活动产物。地球化学成分上,岩石具有富硅(SiO_2=62.21%~83.21%)、高钾(K_2O/Na_2O=3.35~20.27)和富碱(K_2O+Na_2O=5.82%~12.23%)的特点,属于钾玄岩系列。岩石富集轻稀土元素(LREE/HREE=10.26~24.21),亏损重稀土元素,具有弱负铕异常(δEu=0.63~1.07),富集大离子亲石元素(如K、Rb、Pb)和不相容元素(如Th、U)的特征,相对亏损高场强元素(如Nb、Ta、P、Ti)。锆石Hf同位素分析结果表明,东北沟钼矿二长花岗岩的ε_(Hf)(t)值为介于-12.4~-8.5,二阶段模式年龄(t_(DM2))介于442~1610 Ma,反映岩浆源区可能来源于中元古界古老地壳的再熔融。结合区域构造演化,成岩成矿构造背景为早白垩世古太平洋板块向欧亚之下俯冲,岩石圈减薄的构造环境。     

大兴安岭北段宜里地区早侏罗世二长花岗岩U-Pb年龄、地球化学特征及其构造意义

本文对大兴安岭北段宜里地区二长花岗岩进行了系统的地球化学及锆石U-Pb同位素年代学研究,旨在查明其成岩时代及岩石成因,并探讨其构造意义。宜里地区二长花岗岩中的锆石均呈半自形—自形,振荡生长环带明显,暗示其岩浆成因。锆石LA-ICP-MS U-Pb同位素定年结果显示,宜里地区二长花岗岩形成于175.8~174.5 Ma,为早侏罗世岩浆事件的产物。岩石具有富硅（SiO2=71.23%~74. 52%）、富碱更富钾（Na2O+K2O=6.31%~8.31%,K2O=2.58%~4.78%）、贫镁（MgO=0.43%~1.50%）、贫钙（CaO=0.91%~1.81%）的特征,铝饱和指数（A/CNK=0.97~1.16）,属于准铝质—弱过铝质高钾钙碱性花岗岩。富集Rb、Th、K等大离子亲石元素,相对亏损Nb、Ta等高场强元素和P、Ti等元素,轻重稀土元素分馏较强（La/Yb）N=14.07~50.34,无明显Eu异常（δEu=0.88~1.71）。花岗岩熔体的锆石饱和温度（714~745℃）明显低于A型花岗岩（＞800℃）,显示出高分异I型花岗岩的特征。岩石学及地球化学特征表明,宜里地区二长花岗岩的形成与俯冲形成的上涌热流加热新增生下地壳发生部分熔融有关。结合区域构造演化及构造判别,认为研究区早侏罗世二长花岗岩形成于蒙古—鄂霍茨克大洋板片南向俯冲作用相关的活动大陆边缘环境。     

新疆东昆仑木孜塔格地区碎石沟花岗岩锆石U-Pb年代学、岩石地球化学特征及地质意义

碎石沟花岗岩体位于东昆仑造山带西段木孜塔格地区,是该地区几个主要花岗岩体之一。为了查明该岩体的成因类型、物质来源及形成时代,并在此基础上进一步探讨木孜塔格地区的区域构造演化过程及东昆仑造山带地球动力学背景,对该岩体进行了详细的岩石学、地球化学及锆石U-Pb年代学研究。岩石学特征表明,碎石沟花岗岩主要由灰白色中细粒二长花岗岩组成,在岩体边部可见少量灰白色花岗闪长岩。岩石地球化学研究表明,该岩体具有高硅（SiO2=67.54 %~71.56 %）、高碱（Na2O=3.08%~4.50%、K2O=3.05%~4.20%）、富铝的特点（Al2O3=14.26%~16.58%）,属于准铝质—弱过铝质高钾钙碱性系列;稀土元素含量较高（126.31×10-6~160.13×10-6）,总体表现出轻稀土富集,重稀土亏损的右倾式配分模式,具有Eu的弱负异常（δEu=0.68~0.85）;微量元素相对富集Rb、Th、K等大离子亲石元素,亏损Nb、Ta、Hf、Sr等高场强元素,显示出 I 型花岗岩的特征。本次研究获得碎石沟岩体二长花岗岩的锆石U- Pb年龄为208.0±1.1 Ma（MSWD=1.0）,属于晚三叠世岩浆活动产物。结合区域构造演化特征,碎石沟花岗岩来源于下地壳物质部分熔融,并且在形成过程中存在幔源岩浆底侵及壳幔岩浆混合作用,其构造背景为后碰撞环境。     

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