湘南宝山铅锌矿床硫、铅、碳、氧同位素特征及成矿物质来源

宝山铅锌矿床是湘南地区代表性矿床之一。宝山铅锌矿床的成矿作用与156~158 Ma的宝山花岗闪长斑岩密切相关。花岗闪长斑岩主要由古老地壳部分熔融而成。为确定成矿物质来源,文章系统研究了宝山铅锌矿床的硫、铅、碳、氧同位素组成特征。矿床中硫化物黄铁矿、闪锌矿、方铅矿的δ34S值呈狭窄的塔式分布,变化在-2.17‰~6.46‰之间,平均值为3.13‰。δ34S值总体表现为δ34S黄铁矿δ34S闪锌矿δ34S方铅矿,表明硫同位素分馏基本达到了平衡。矿石、花岗闪长斑岩和赋矿地层硫同位素对比研究表明,矿石中的硫主要由岩浆分异演化而来,岩浆中的硫主要来自古老地壳。矿石206Pb/204Pb、207Pb/204Pb和208Pb/204Pb比值分别为18.188~18.844、15.661~15.843和38.562~39.912,赋矿地层206Pb/204Pb、207Pb/204Pb和208Pb/204Pb比值分别为18.268~19.166、15.620~5.721和38.364~39.952。矿石铅同位素组成比地层中的更富放射性成因铅,矿石中部分铅来自宝山花岗闪长质岩浆,在成矿流体运移过程中有部分地层铅参与了成矿,岩浆中的铅主要来自古老地壳。热液方解石的碳、氧同位素组成介于岩浆和赋矿碳酸盐岩的碳、氧同位素之间,主要是由于岩浆流体和碳酸盐岩不同比例的水岩反应所致,测水组有机碳的加入造成了部分热液方解石δ13CPDB值偏低。     

新城金矿稳定同位素地球化学特征及成矿物质的来源

新城金矿是胶东金矿集区招远—莱州成矿带的一个"焦家式"蚀变型金矿床。本文主要通过C、H、O、S、Pb同位素研究,对新城金矿成矿流体、物质来源和成矿作用进行探讨和研究。新城金矿矿石中δD值范围为-116‰~-91‰,δ18O水值范围为3.8‰~7.2‰,表明成矿流体早期来源于岩浆水,成矿晚期混入大气降水。矿石硫化物、郭家岭花岗闪长岩、玲珑花岗岩和胶东群δ34S平均值分为7.9‰、6.5‰、8.5‰和6.2‰,认为矿石硫具有对矿区地层及岩浆岩硫的继承性。硫化物矿石206Pb/204Pb=17.115~17.414,207Pb/204Pb=15.460~15.577,208Pb/204Pb=37.912~38.196,显示铅具有壳幔混合来源的特征。碳、氢、氧、硫、铅同位素反映新城金矿成矿物质和流体主要来源于深部岩浆。     

新城金矿稳定同位素地球化学特征及成矿物质来源探讨

新城金矿是胶东金矿集区招远—莱州成矿带的一个"焦家式"蚀变型金矿床。本文主要通过C、H、O、S、Pb同位素研究,对新城金矿成矿流体、物质来源和成矿作用进行探讨和研究。新城金矿矿石中δD值范围为-116‰~-91‰,δ18O水值范围为3.8‰~7.2‰,表明成矿流体早期来源于岩浆水,成矿晚期混入大气降水。矿石硫化物、郭家岭花岗闪长岩、玲珑花岗岩和胶东群δ34S平均值分为7.9‰、6.5‰、8.5‰和6.2‰,认为矿石硫具有对矿区地层及岩浆岩硫的继承性。硫化物矿石206Pb/204Pb=17.115~17.414,207Pb/204Pb=15.460~15.577,208Pb/204Pb=37.912~38.196,显示铅具有壳幔混合来源的特征。碳、氢、氧、硫、铅同位素反映新城金矿成矿物质和流体主要来源于深部岩浆。     

滇西保山地块金厂河铁铜铅锌多金属矿床硫铅同位素特征与成矿物质来源示踪

滇西金厂河铁铜铅锌多金属矿床位于保山地块北部,是"三江"多金属成矿带内典型矿床之一。对该矿床开展硫铅同位素示踪研究,探讨成矿物质来源,并结合构造背景和成矿时代分析了矿床成矿机制。样品测试结果表明,矿石中硫化物的δ~(34)S值为+2.5‰～+11.1‰,平均值为+5.65‰,硫同位素来源为深部幔源岩浆和岩浆上侵混染壳源物质形成的多种硫源同位素组合;矿石矿物铅同位素组成中~(206)Pb/~(204)Pb为18.167～18.497,~(207)Pb/~(204)Pb为15.668～15.779,~(208)Pb/~(204)Pb为38.554～38.997,铅同位素总体较稳定,显示壳幔混染特征,以上地壳铅为主,可能来源有深部侵入岩浆及赋矿围岩。由矿床成矿物质来源表现出的多源、深源-浅源的特征推测,与成矿有关的中酸性岩体隐伏在区域深部。     

西藏加多捕勒铁铜矿床硫、铅同位素组成及成矿物质来源

加多捕勒铁铜矿床位于念青唐古拉成矿带西段。综合研究围岩、岩体与矿石的硫、铅同位素组成,发现其矿石硫化物的δ~(34)S值变化范围为-2.1‰～6.2‰,δ~(34)S_(ΣS)值为2.16‰,总体具有岩浆硫的特征。矿石硫化物的δ~(34)S值与石英闪长岩、板岩中硫化物的δ~(34)S值相近,表明矿石的硫源可能部分由板岩与石英闪长岩提供。矿石铅同位素组成比较均一,~(206)Pb/~(204)Pb、~(207)Pb/~(204)Pb和~(208)Pb/~(204)Pb的变化范围分别为18.27～18.842、15.653～15.899和38.793～39.703,与冈底斯成矿带北亚带矿床矿石硫化物的铅同位素组成相近,具有上地壳铅源的特征。矿石铅同位素组成与黑云母二长花岗岩、大理岩的铅同位素组成一致,显示铅可能主要来源于黑云母二长花岗岩和大理岩。综合分析表明,加多捕勒铁铜矿床硫、铅同位素的研究显示其成矿物质可能主要来源于黑云母二长花岗岩,部分来源于中二叠统下拉组岩石,少量由石英闪长岩提供,它们为深入研究该矿床的成矿模式提供了资料。     

湘南铜山岭铜多金属矿床成矿物质来源的 S、Pb、C同位素约束

铜山岭铜多金属矿床是湘南W、Sn、Pb、Zn、Cu多金属矿集区的代表性矿床,本文对其不同类型岩石和矿石矿物进行了S、Pb、C同位素组成对比研究。矿石硫化物的δ34 S值变化范围为-1.9‰~5.7‰,平均值为2.6‰,硫主要来源于硫同位素组成均一化的岩浆。硫化物硫同位素平衡温度表明,矿床主要成矿温度为134~339℃。矿石铅的206 Pb/204 Pb、207 Pb/204 Pb、208 Pb/204 Pb比值分别为18.256~18.856、15.726~15.877、38.352~39.430;岩体岩石铅的206Pb/204Pb、207Pb/204Pb、208Pb/204Pb比值分别为18.617~18.805、15.721~15.786、38.923~39.073;两者铅同位素组成相同,都主要为上地壳铅,是由同一岩浆体系分异形成,可能来源于古老基底岩石。不同类型岩石、方解石矿物的δ13 CPDB值为-9.88‰~1.32‰,δ18 OSMOW值为11.67‰~17.68‰,从矽卡岩矿体到距岩体稍远的围岩地层,方解石矿物的δ13 CPDB、δ18 OSMOW值逐渐增大,成矿流体中的碳早期可能主要来源于岩浆,在成矿过程中有部分碳酸盐岩地层碳的加入。铜山岭矿床成矿物质主要来源于岩浆,赋矿地层对矿床成矿物质来源作用不显著,仅提供了少量成矿物质。     

西藏洞中拉铅锌矿床S,Pb,Sr同位素组成对成矿物质来源的示踪

洞中拉铅锌矿床位于西藏冈底斯东段念青唐古拉山地区扎雪—金达成矿带内,为印度—亚洲大陆主碰撞期形成的矿床.在分析该矿床成矿地质条件的基础上,对该矿床的主要金属硫化物的S,Pb,Sr同位素组成进行分析,并对成矿物质来源进行示踪讨论.研究表明:矿石硫化物的δ34S组成变化范围较窄,变化范围为3.0‰～5.7‰,多数集中于4.0‰～6.0‰之间,具有塔式分布效应,估算的总硫同位素值δ34 S∑s为4.7‰,具有岩浆硫的特征.矿石铅同位素组成稳定,矿石的206Pb/204Pb,207Pb/204Pb,208Pb/204Pb的变化范围分别为:18.628～18.746,15.698～15.802,39.077～39.430,与矿区岩浆岩的铅同位素组成一致,为正常普通铅,矿石铅来源于早白垩世上地壳物质部分熔融形成的岩浆.矿石锶同位素的初始值(87 Sr/86 Sr)i较高,介于0.717 32～0.727 67之间,成矿物质来源于地壳.     

黔西南紫木凼金矿床成矿物质来源:S⁃C⁃O⁃Pb⁃Sr同位素制约

紫木凼金矿床是黔西南卡林型金矿区一个重要的大型金矿床,其成矿物质来源尚不明确.对紫木凼金矿床不同类型矿石和赋矿围岩进行了S、C、O、Pb和Sr同位素组成对比研究.矿石中硫化物的δ34S值为-13.49‰~17.91‰（主要为-0.99‰~3.58‰）,赋矿围岩的δ34S值为-26.23‰~-19.63‰,矿床成矿期硫主要来源于岩浆,部分来源于赋矿地层中成矿前黄铁矿.热液期方解石的δ13C和δ18O分别为-9.10‰~0.59‰和15.65‰~23.82‰,与赋矿围岩、区域地层的碳、氧同位素组成差别较大,成矿流体的碳、氧部分来源于碳酸盐岩溶解,部分可能来源于岩浆.矿石中硫化物的206Pb/204Pb、207Pb/204Pb和208Pb/204Pb比值分别为18.064~18.973、15.585~15.670和38.219~39.054,赋矿围岩的206Pb/204Pb、207Pb/204Pb和208Pb/204Pb比值分别为18.136~18.650、15.574~15.656和38.423~38.812,矿石铅的来源较复杂,赋矿地层和岩浆可能都为其提供了部分铅.矿石中石英和方解石（87Sr/86Sr）_i比值为0.707 26~0.708 11,赋矿围岩的（87Sr/86Sr）_i比值为0.707 28~0.707 31,成矿流体中的锶主要来源于赋矿地层.紫木凼金矿床成矿物质具壳幔混合来源特征,成矿物质主要来自矿床深部隐伏岩浆岩,部分来自二叠系-三叠系赋矿地层.      

内蒙古1017高地银多金属矿床地质地球化学特征及成因探讨

1017高地银多金属矿床位于内蒙古自治区东乌珠穆沁旗,矿区大地构造位置处于西伯利亚板块东南缘查干敖包-奥尤特-朝不楞早古生代构造-岩浆岩带东段。石英脉型矿石中流体包裹体研究显示,从成矿早期到主成矿期,流体温度逐渐降低(从404℃~134℃到236℃~121℃),盐度都为中低盐度,由此表明该矿床具有浅成、中低温、中低盐度热液成矿特征。激光拉曼光谱分析显示包裹体气液相成分主要为H2O。矿石硫同位素组成相对均一,δ34S介于3.4‰~8.0‰之间,均值5.35‰,与幔源S的δ34S值(介于-3‰~3.0‰之间)比较,有向沉积硫的明显漂移,表明矿石中硫来源于沉积硫与岩浆硫的混合、平衡作用;矿石硫化物铅同位素比值没有明显的差别,206Pb/204Pb值为18.274 0~18.399 6,207Pb/204Pb值为15.539 9~15.561 6,208Pb/204Pb值为38.036 3~38.177 2,具有钍铅微弱亏损特征,指示矿石中硫化物的铅源主要来自地壳深部的岩浆源区,伴随岩浆及其热液作用,不可避免地混入了部分富放射成因铅的地壳物质。矿石氢氧同位素组成为:δDV-SMOW值介于-103‰~-125‰之间,δ18 OV-SMOW值在6.9‰~13.9‰之间,显示成矿流体中的水来源于岩浆水与大气降水的混合。综合1017高地银多金属矿床的地质特征和流体包裹体、S,Pb,H,O同位素研究认为,该矿床成矿物质来源于深源岩浆和上地壳的混合,成矿流体主要来自岩浆期后热液和大气降水,其成因类型可归于中低温度、中低盐度的岩浆期后热液型银多金属矿床。     

江西德兴朱砂红斑岩铜矿床H-O-S-Pb同位素特征及意义

江西德兴斑岩铜矿田位于扬子地块东南缘,毗邻赣东北深断裂;该矿田由富家坞、铜厂及朱砂红矿床组成,属世界超大型斑岩铜矿。本文在系统的野外观察及室内岩相学观察的基础上,通过H、O、S、Pb同位素地球化学研究手段,探讨该矿床的成矿流体及成矿物质来源。H、O同位素研究结果显示,矿石石英脉中石英的δ~(18)O值范围为8.4‰~11.2‰,与之平衡的δ~(18)O_(H_2O)值范围分别为0.44‰~3.14‰,含矿石英脉中石英的δD值范围为-73.2‰~56.9‰,成矿流体以岩浆分异热液及天水热液为主。矿石中硫化物δ~(34)S组成变化范围较窄,为-4.3‰~-0.9‰,多数集中在0值左右且在S同位素直方图上呈塔式分布特点,表明具有岩浆硫(0±3‰)的特征。矿石硫化物中Pb同位素组成比较稳定,~(206)Pb/~(204)Pb、~(207)Pb/~(204)Pb和~(208)Pb/~(204)Pb比值分别为18.079~18.643、15.545~15.578和38.058~38.595。朱砂红矿床硫化物中Pb同位素组成与德兴含矿斑岩大致相同,明显区别于源自双桥山群地层的矿石中Pb同位素组成,表明成矿物质主要来源于含矿斑岩,并非双桥山群浅变质地层。朱砂红矿床的流体来源为岩浆分异热液及天水热液的混合,成矿物质主要来自斑岩,矿床发育与斑岩体密切相关。德兴矿区三个矿床对比研究表明,朱砂红斑岩型矿床H、O同位素特征与铜厂斑岩铜矿床大体一致,成矿流体来源基本相似;三个矿床中S同位素表现为从东南的富家坞矿床向西北的朱砂红矿床由高到低的变化趋势,但变化范围基本保持一致,朱砂红矿床可能比铜厂矿床及富家坞矿床受更多围岩物质混染;三个矿床Pb同位素总体显示出壳幔混合铅的特征。三个矿床为同一成矿系统,矿床的差异可能源自岩浆与围岩混染程度的不同。     

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