云南因民铁铜矿区次火山杂岩中黑云母和绿泥石矿物化学特征与成矿指示

云南因民铁铜矿区次火山杂岩主要由铁质熔岩、辉绿岩、辉长辉绿岩、火山集块岩、火山角砾岩、热液角砾岩等组成,岩相分带明显,热液蚀变与矿化关系密切。通过对次火山杂岩中不同岩相的黑云母和绿泥石电子探针结果分析得出,黑云母为镁质黑云母,大多数为再平衡黑云母,形成温度为505~590℃,lgf(O2)为-12.4~-5.25,压力为116~226 MPa,推测成岩深度为4.27~8.37 km,属于高温强氧化环境;绿泥石为密绿泥石、蠕绿泥石、透绿泥石、叶绿泥石,形成温度为170~235℃,lgf(O2)为-51.93~-43.70,lgf(S2)为-13.34~-2.50,属于中低温强还原环境。矿物产状、矿物组合与矿物中主要阳离子关系显示,两种矿物均具有多期多源性的特征。黑云母化蚀变代表铁矿的主成矿期,绿泥石化蚀变代表铜矿的主成矿期;多期次构造-岩浆-热事件形成了高-中低温的碱性强还原流体,叠加改造富集铁铜矿床,揭示了本区次火山杂岩是铁铜矿床稳定持续性成矿元素的供给系统。     

粤西河台金矿床富硫化物石英脉Rb-Sr等时线年龄讨论

河台金矿床产于河台韧性剪切带中,成矿作用分为韧性剪切变质成矿期的韧性剪切变质成矿阶段和热液蚀变成矿期金石英脉阶段、金硫化物阶段和方铅矿闪锌矿碳酸盐脉阶段.金的成矿主要发生在金石英脉阶段和金硫化物阶段,形成的矿石有蚀变糜棱岩型和富硫化物石英脉型.富硫化物石英脉单矿物石英中富含以富CO2液相为主的流体包裹体、流体熔融包裹体及熔融包裹体.与以往用流体包裹体热爆法和压碎法提取Rb、Sr的方法不同,本文用石英全溶法测得富硫化物石英脉中石英的Rb-Sr等时线年龄为172±2 Ma(1σ),初始比值为0.72816±0.00096,对比已有的同位素年龄数据及区域成矿特征,认为这一年龄值可能代表了河台金矿床的成矿年龄.     

辽宁青城子矿集区铅锌-银-金矿床硫化物化学成分及找矿意义

对辽宁青城子铅锌-银-金矿床的主要矿石矿物方铅矿、闪锌矿和黄铁矿进行了显微鉴定、电子探针和ICP-MS分析,获得它们的固结顺序为:黄铁矿早于闪锌矿,二者早于方铅矿(闪锌矿交代黄铁矿,方铅矿交代前两者)。从硫化物成分空间分布可以判断成矿流体以甸南-榛子沟为中心分别向二道-喜鹊沟和大地-白云迁移。根据方铅矿固结温度(327℃)参考石英流体包裹体均一温度(322℃),限定以方铅矿为主的矿床其硫化物形成温度约为322～327℃;利用Cd在方铅矿-闪锌矿分配系数温度计获得铅锌矿成矿温度在344～464℃之间,结合闪锌矿出溶黄铜矿温度(高于350℃),参考石英流体包裹体均一温度(300～360℃),并参考黄铁矿发生脆性变形温度(400℃),获得以闪锌矿为主的矿床硫化物形成温度约为360～400℃,银铅锌矿床的成矿温度被限定在390～400℃;由于自然金主要赋存在黄铁矿微裂隙中,利用黄铁矿发生脆性变形温度并结合石英流体包裹体温度(230～370℃)约束金成矿温度约为370～400℃。成矿温度较高可能归因于样品采集位置较深所致;最后利用矿石矿物、侵入岩、围岩微量元素对比分析判断成矿流体与中生代(特别是...     

粤西河台金矿床富硫化物含金石英脉锆石U-Pb 测年及成矿意义

河台金矿是一个强烈受韧性剪切带控制的金矿床,金的成矿主要发生在热液蚀变成矿期的金石英脉阶段和金硫化物阶段,形成的矿石有蚀变糜棱岩型和富硫化物石英脉型.富硫化物含金石英脉中单颗粒锆石U-Pb同位素测年显示早加里东期是河台金矿床主成矿期,成矿年龄为492±16Ma;矿区燕山期伍村花岗岩的单颗粒锆石年龄为153.6±2.1Ma;结合已有的同位素资料,认为河台金矿床是华南加里东期构造-变质-岩浆作用及成矿作用的一个组成部分,是一个早加里东期造山作用同期的造山带型金矿床,并可能有燕山期的热液叠加成矿作用.     

江南造山带黄金洞金矿床成矿机制:矿物形成环境与金成矿物理化学条件制约

黄金洞超大型金矿床位于江南造山带中段,赋存于新元古界浅变质岩系中,受控于NNE-NE向长平断裂带,金资源储量达100吨。该矿床可由南至北分为金福、金塘、杨山庄和曲溪矿段,主要矿化类型有石英-硫化物脉型、构造角砾岩型和黄铁毒砂绢英岩型。金属矿物主要发育有自然金、毒砂、黄铁矿、黄铜矿、闪锌矿、方铅矿、磁黄铁矿等;非金属矿物有石英、绢云母、方解石和菱铁矿等,其中金主要以自然金与不可见金形式存在。根据野外与镜下观察,金成矿作用分为Ⅰ石英-金-毒砂-黄铁矿、Ⅱ石英-金-多金属硫化物-白钨矿和Ⅲ石英-辉锑矿-绿泥石3个阶段,前二者为主要成矿阶段。曲溪矿段Ⅱ阶段毒砂相对不发育、而磁黄铁矿和自然金显著发育,绿泥石主要发育于Ⅲ阶段中,与辉锑矿及闪锌矿共生。根据不同矿段各阶段毒砂与Ⅲ阶段绿泥石成分,计算其温度、lgf(S_2)与lgf(O_2),可见Ⅰ阶段成矿温度与硫逸度高于Ⅱ阶段:杨山庄矿段两阶段成矿温度分别为300～378℃、260～300℃,lgf(S_2)分别为-11～-7.2、-11.9～-10.1;金塘两阶段成矿温度为240～311℃、245～298℃;金福Ⅱ阶段成矿温度上限为297℃;曲溪矿段成矿温度为268～368℃,Ⅱ阶段毒砂lgf(S_2)与Ⅲ阶段绿泥石lgf(O_2)分别为-13.2～-8.7、-50.9～-40.1。根据不同阶段矿物之间的相互关系及成矿温度与硫逸度演化特征,推断Ⅰ、Ⅱ成矿阶段伴随强烈的硫化作用,金以类质同象方式进入毒砂和黄铁矿中,形成不可见金;其中Ⅱ阶段由于成矿流体压力骤降,含金流体发生相分离作用,H2S等气体大量逃逸,导致成矿流体中硫含量骤降,加以硫化作用持续消耗流体中的硫,促进了含金络合物分解与自然金的沉淀。     

相山铀矿田北部花岗斑岩黑云母及绿泥石矿物化学特征与地质意义

相山铀矿田为中国最大的火山岩型铀矿田,其中北部花岗斑岩型铀矿床资源储量占总储量的36.65%。虽然前人对相山矿田北部花岗斑岩进行了系统研究,但是关于花岗斑岩中矿物化学研究较为薄弱。本次研究运用电子探针技术对相山北部花岗斑岩中黑云母及绿泥石进行了矿物化学分析,并探讨了成岩成矿意义。结果表明:(1)相山北部产铀花岗斑岩黑云母为铁质黑云母。花岗斑岩岩浆结晶温度为721～753℃,平均737℃,氧逸度lgf(O₂)为-14.8～-15.7,形成压力为112～147 MPa,侵位结晶深度为4.1～5.4 km。岩石成因类型为A型花岗岩,形成于板内拉张构造环境,物质来源于上地壳部分熔融;(2)相山北部绿泥石为蠕绿泥石属于富铁绿泥石,形成于还原环境。绿泥石形成温度为230～271℃,平均值为258℃,属于中温热液作用范围;(3)花岗斑岩中铀的载体主要为黑云母包体中含铀副矿物。矿前期,热液流体交代黑云母形成绿泥石,使得黑云母内含铀副矿物中的铀活化转移为分散吸附状态的铀,被绿泥石等矿物吸附于矿物晶格表面或矿物裂隙为成矿期热液提供了铀源。     

藏南扎西康矿集区姐纳各普金矿床地质与流体包裹体特征

姐纳各普金矿床位于藏南金锑成矿带东段,是近年来在扎西康矿集区内新发现的岩金矿床。矿床产于蚀变辉绿岩中,矿体受北西-南东向韧脆性断裂及层间破碎带控制。矿石类型有蚀变岩型和石英脉型2种,呈网脉状、角砾状及定向构造,土状、结晶、碎裂、糜棱结构;矿石中金属矿物主要为黄铁矿、毒砂、辉锑矿、方铅矿、闪锌矿及自然金,脉石矿物以石英、绢云母及绿泥石为主;围岩蚀变主要为黄铁绢英岩化和绿泥石化;据脉体穿插和矿物共生组合,将原生热液成矿期分为石英-黄铁矿(早)、石英-金-贱金属硫化物(中)和石英-碳酸盐矿物(晚)3个阶段。对矿石中石英流体包裹体研究显示,矿床主成矿阶段(中)流体包裹体主要为由纯CO_2、水溶液和富CO_2-水溶液流体包裹体3种所构成的非均一捕获流体包裹体组合(F.I.A.),均一温度为221.7~279.4℃,盐度为1.57%~6.74%,流体密度为0.58~0.88 g/cm~3,属中低温、低盐度、低密度、富CO_2的H_2O-Na Cl-CO_2±CH_4±N_2体系。主成矿阶段内见均一温度相近的不同类型包裹体和同类型具不同气液比的包裹体共存于同一视域,显示成矿流体的不混溶性,成矿温度为218.6~280.4℃,成矿压力为73~93 MPa。据成矿压力估算得成矿深度为5.8~7.9 km,成矿时的地温梯度为35~45℃/km。矿床地质特征及成矿流体性质表明,姐纳各普金矿床为与岩浆或岩浆热液活动有关的造山型金矿床,成矿与中新世印度—欧亚大陆碰撞挤压向伸展作用的转换有关。     

新疆阿希与塔吾尔别克金矿床的成因联系：来自流体包裹体、S- Pb同位素和黄铁矿热电性的证据

新疆西天山吐拉苏盆地中的阿希和塔吾尔别克金矿床空间上毗邻,但矿化特征差异明显。矿相学和扫描电镜- 能谱成分分析表明,阿希金矿床矿石中金属矿物主要为黄铁矿、毒砂和白铁矿,塔吾尔别克金矿床矿石中金属矿物除黄铁矿外,还普遍发育黄铜矿、斑铜矿、黝铜矿、砷黝铜矿、闪锌矿和砷锑镍矿。两个矿床的流体包裹体均为盐水包裹体,具有低温、低盐度的特征。阿希金矿床浅地表黄铁矿的电子导型主要为P型,形成温度为 160~240℃(平均195℃);塔吾尔别克金矿床浅地表黄铁矿以N+P混合型为主,N型和P型黄铁矿的形成温度分别为300~380℃(平均352℃)和80~240℃(平均137℃)。矿石中矿物组合和组构、流体包裹体和黄铁矿热电性特征显示,塔吾尔别克金矿床的成矿温度明显大于阿希金矿床。阿希和塔吾尔别克金矿床矿石中黄铁矿单矿物 δ 34 S值范围分别为-4. 0‰~5. 3‰(平均0. 7‰)和0. 6‰~4. 7‰(平均2. 5‰),载金黄铁矿原位 δ 34 S值范围分别为-2. 6 ~5. 6‰(平均2. 4‰)和1. 9‰~3. 8‰(平均2. 9‰),表明两个矿床具有一致的单一硫源,即岩浆硫。两个矿床矿石中黄铁矿的Pb同位素组成相似,并与赋矿大哈拉军山组火山岩和花岗斑岩大致相同,表明成矿物质来源于赋矿岩浆岩。流体包裹体、特征性矿物和矿石组构特征表明,流体沸腾作用导致了阿希金矿床金的沉淀。矿体形态产状、矿物组合、矿石组构、围岩蚀变、成矿物质来源等特征表明,阿希属于典型的低硫型浅成低温热液金矿床,塔吾尔别克可能属于斑岩与浅成低温热液之间过渡型的次浅成低温热液矿化。综合黄铁矿电子导型、矿体剥蚀率、矿物组合、矿石组构和岩体/地层出露情况等特征,推测塔吾尔别克金矿的剥蚀程度明显强于阿希金矿床,其深部可能存在隐伏的斑岩型Cu- Au矿化。     

胶东辽上金矿床的流体包裹体、氢-氧-碳-硫-铅同位素特征及矿床成因

辽上金矿床位于胶莱盆地东北缘, 是胶东东部唯一的超大型金矿床。通过流体包裹体和氢-氧-碳-硫-铅同位素地球化学特征研究, 探讨辽上金矿的成因。主成矿阶段流体包裹体完全均一温度变化范围为125~345℃, 主成矿温度集中于260~320℃, 盐度为2.22%~13.87%NaCleqv, 流体密度为0.68~1.02 g/cm3, 成矿流体属于中—低温度、中—低盐度、低密度, 为富含CO2的还原性质热液体系。氢、氧同位素(δD=-82.6‰~-68.9‰, δ18OW-SMOW=-0.24‰~+3.33‰)和流体包裹体成分指示, 成矿流体为地幔初生水热液及岩浆热液+大气降水的混合流体。碳、氧同位素组成(δ13CPDB=-2.9‰~-4.7‰, δ18OSMOW=6.9‰~9.6‰, )指示成矿流体中碳来源于花岗岩源区。矿石δ34S介于7.6‰~12.6‰之间, 206Pb/204Pb值为17.202~17.955, 207Pb/204Pb值为15.457~15.577, 208Pb/204Pb值为37.729~38.341, 指示铅源主要来自下地壳的早前寒武纪变质岩系, 可能有少量幔源铅的贡献。研究认为, 辽上金矿床是与早白垩世伟德山型花岗岩有关的岩浆热液金矿, 与壳幔混合花岗岩浆活动有关的岩浆热液、地幔流体在热隆-伸展构造作用下与大气降水混合产生流体不混溶而成矿。     

吉林延边百草沟金矿成矿流体特征和矿床成因

百草沟金矿位于著名的五凤—小西南岔浅成低温热液型金--多金属成矿带,该矿床容矿围岩主要为花岗闪长岩,矿体严格受NW向韧性剪切带控制。含矿石英中流体包裹体发育气液两相包裹体,主要成分为水,气液比15%~30%,大小为2~12μm。均一温度为154.3℃~345.2℃,盐度w(Na Cl)2.73~19.71 wt%Na Cl,密度0.63~1.00 g/cm3,表现出低温、中低盐度、中低密度、盐度变化范围大的特征。通过估算,成矿压力为14.70~47.16 MPa,成矿深度为1.47~5.46 km。百草沟金矿床δ13CCO2变化不是很大,介于-6.7‰~-4.6‰之间,显示有幔源的可能;硫化物中34S值为-1.9‰~1.9‰,说明成矿硫具有深源性。成矿早阶段流体为中低盐度的中温流体,主成矿阶段由于大气降水的混入,导致温度与盐度快速下降,逐渐演变为低温、低密度的盐水溶液。围岩蚀变以冰长石化、碳酸盐化等低温蚀变矿物为主。百草沟金矿属于低硫化型浅成低温热液型金矿床,形成于太平洋板块向欧亚板块俯冲后的伸展构造背景。     

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