南岭科学钻探一孔中岩浆岩的矿物特征及其对成岩、成矿作用的指示意义

南岭科学钻探一孔(SP-NLSD-1)位于南岭成矿带与武夷山成矿带的交汇部位——赣南银坑矿田,该钻孔总进尺2967.83 m,钻遇了流纹岩、花岗闪长斑岩、花岗斑岩、辉长闪长玢岩等4种岩浆岩。各岩浆岩矿物组成简单,主要为石英、斜长石、钾长石、黑云母、角闪石及副矿物磷灰石、榍石等,岩石多发生绿泥石化、碳酸盐化、白云母化等蚀变。钾长石均以正长石为主。花岗闪长斑岩中的斜长石以中长石为主,少数为钠长石、更长石、拉长石;花岗斑岩中的斜长石以钠长石为主,少数为更长石。黑云母为富镁黑云母和镁铁黑云母。白云母均由黑云母蚀变而来,花岗闪长斑岩中的白云母具有低的AlVI、Fe/(Fe+Mg)值,花岗斑岩中的白云母具有高的AlVI、Fe/(Fe+Mg)值。磷灰石普遍含F、Cl,且F含量显著高于Cl含量。石榴石属钙铝榴石。绿泥石主要为蠕绿泥石(铁绿泥石)-密绿泥石。黑云母矿物化学特征指示花岗闪长斑岩为壳幔混源花岗岩,具有较高的氧逸度,在演化过程中发生了岩浆混合作用。根据锆石饱和温度计计算出花岗闪长斑岩、花岗斑岩、辉长闪长玢岩的结晶温度分别为810~922℃、764~819℃、742~747℃,成岩后岩浆岩经历了中高温—中低温热液蚀变作用。岩浆岩成岩时代、岩石学和岩相学所反映的岩浆演化过程、成岩物理化学条件、矿物化学特征等方面的综合信息显示,南岭科学钻探一孔中钻遇的花岗闪长斑岩与南岭地区成Cu(-Mo)-Pb-Zn-Au-Ag矿的花岗岩十分相似,应为钻孔中揭露的银金铅锌铜矿化以及牛形坝—柳木坑银金铅锌铜矿的成矿岩浆岩,而钨铋铀矿化与岩浆岩的关系还有待于进一步研究。     

滇西北春都斑岩铜矿床侵入岩岩石地球化学

春都斑岩铜矿床的侵入岩主要为闪长玢岩和花岗闪长斑岩,文章对其进行了岩石学、地球化学研究.研究表明春都斑岩铜矿床侵入岩属于钙碱性系列,产出于俯冲构造环境.闪长玢岩、花岗闪长斑岩富集大离子亲石元素Sr、K、Rb、Ba、Th,相对亏损高场强元素Ta、Nb、P、Hf、Ti.稀土元素球粒陨石标准化曲线显示轻稀土富集,分配曲线右倾...     

宁芜火山岩盆地凹山铁矿床侵入岩锆石微量元素特征及其地质意义

凹山铁矿床是玢岩铁矿床的典型代表之一,矿床中发育有辉石闪长玢岩和花岗闪长斑岩两类侵入岩。锆石微量元素分析结果显示,两类岩浆岩中锆石的稀土元素配分模型相似,花岗闪长斑岩中的锆石较辉石闪长玢岩中锆石具有较高的U含量,较高的U/Yb比值以及相似的Yb、Hf和Y含量,结合前人的研究认为,两者的源区具有一致性,均源于富集地幔,并在其上涌就位过程中混染了壳源物质,其中花岗闪长斑岩混染了更多的壳源物质。花岗闪长斑岩中锆石的Ce(Ⅳ)/Ce(Ⅲ)比值集中于0～100,远低于斑岩铜矿成矿岩体Ce(Ⅳ)/Ce(Ⅲ)>300的特征,具有较弱的形成斑岩型铜金矿的特征,但在宁芜地区发育的这类花岗闪长斑岩是否具有形成铜金矿化的潜力仍需进一步的研究和勘查。     

吉林延吉杜荒岭浅成热液金矿床岩体锆石微量元素地球化学特征及其地质意义

杜荒岭金矿床是中国东北部吉林省延吉地区典型的浅成热液高硫化型金矿床之一,矿区内发育大量早白垩世火成岩。为了更深入地认识杜荒岭金矿床的岩浆作用、岩浆起源及成矿条件,本文在已有研究基础上对矿区内含矿的石英闪长岩、花岗闪长岩和花岗闪长斑岩中的锆石进行了微量元素测试。结果显示,绝大多数锆石Th/U值>0.1,锆石的球粒陨石标准化REE配分曲线呈左倾配分型式,强烈富集重稀土元素、亏损轻稀土元素,并存在不同程度的Ce正异常与Eu负异常;研究对象为典型岩浆锆石,结晶温度主要介于700～900℃之间。研究认为含矿岩石起源于下地壳部分熔融,形成于板块俯冲的弧构造环境。此外,成矿岩体花岗闪长斑岩锆石相比成矿前岩石具有较高的Ce⁴⁺/Ce³⁺值和较低的结晶温度,指示花岗闪长斑岩岩浆具有高氧逸度和含水量,即高成矿潜力。而岩浆氧逸度和含水量的差异可能是石英闪长岩和花岗闪长岩未成矿的原因。     

西藏多不杂斑岩铜矿斑岩锆石U-Pb年龄、岩石地球化学特征及其成矿意义

西藏多不杂斑岩铜矿位于西藏北部,是青藏高原中部发现的第一个斑岩铜矿。多不杂斑岩铜矿内有两期花岗闪长斑岩和最晚期的闪长玢岩侵位,其中第二期侵位的花岗闪长斑岩是多不杂矿床的主要成矿斑岩。本文开展了多不杂矿床三期斑岩的锆石U-Pb年龄、全岩岩石地球化学和Sr-Nd-Hf同位素组成分析。锆石U-Pb测年结果显示,斑岩在120Ma集中侵位。较早侵位的两期花岗闪长斑岩均富集轻稀土、大离子亲石元素,亏损重稀土、高场强元素,Eu异常不明显,显示出岛弧岩浆岩的特征,均具有高Sr低Y的特征,(87 Sr/86 Sr)i值0.7057~0.7062和0.7059~0.7064,εNd(t)值为较小的负值(-2.5~-1.7和-6.2~-4.0),第二期花岗闪长斑岩的εHf(t)值为3.7~7.5,显示两期花岗闪长斑岩均属于类埃达克质岩石,可能起源于新生下地壳角闪岩相,有幔源物质混入。最晚侵位的闪长玢岩与两期花岗闪长斑岩岩石化学特征类似,但具有富钠特征,其MgO、Y、Yb等含量相对较高,可能表明闪长玢岩与花岗闪长斑岩源区相同,有更多幔源物质混入。多不杂斑岩铜矿可能形成于班公湖-怒江洋向北俯冲末期,可能产出于陆缘弧环境。     

湖南界牌岭锡多金属矿地球化学、年代学特征及成矿区带归属

湖南界牌岭锡多金属矿位于南岭中部,主要矿化为大规模缓倾斜顺层分布的含矿云母黄玉蚀变岩和云母萤石蚀变岩型锡矿、铍矿以及萤石矿化。成矿地质体为碱长花岗斑岩,具有高硅、低钙、过铝特征,钠长石An值平均为0.11;∑REE平均值高达698.19×10-6,稀土元素配分曲线呈Eu轻度亏损的右倾型,同时富含成矿元素及挥发性元素,其中含F可达0.12%。锆石的SHRIMP U-Pb年龄为92±1Ma(MSWD=1.5)。综合对比南岭成矿带、右江成矿带主要矿床与界牌岭锡多金属矿床的地质地球化学特征,认为界牌岭的成矿地质体和成矿地质特征明显不同于南岭燕山早期相关的钨矿床,而与右江成矿带燕山晚期锡多金属成矿作用更为密切,是右江燕山晚期锡多金属成矿带的东延。     

湖南宝山-大坊矿区成矿花岗闪长斑岩的锆石U-Pb年龄、Hf同位素及微量元素组成对区域成矿作用的指示

钦-杭成矿带是华南地区新近识别出的一条重要的中生代斑岩-矽卡岩型铜多金属成矿带。宝山矿床处于铜山岭-宝山-水口山矿区的中部,是湘南地区最大的铜多金属矿床,而大坊金矿床与宝山Cu-Mo-Pb-Zn矿相邻,在空间上亦与花岗闪长斑岩密切相关。矿区内岩浆活动复杂,矿化类型齐全,成矿元素多样。我们对宝山成矿花岗闪长斑岩、花岗闪长质隐爆角砾岩和大坊成矿花岗闪长斑岩进行了LA-MC-ICP-MS锆石U-Pb测年,结果表明宝山花岗闪长斑岩、花岗闪长质隐爆角砾岩和大坊花岗闪长斑岩的侵位年龄分别为156. 3±0. 9Ma、157. 1±1. 8Ma和154. 5±1. 0Ma,三者在误差范围内一致,均为晚侏罗世岩浆活动的产物;锆石Hf同位素研究表明,宝山和大坊矿床的成矿岩体均主要为古元古代地壳物质部分熔融的产物,并有幔源组分的加入;锆石微量元素分析结果显示,上述三类岩石的锆石具有相似的稀土元素配分模式,显示它们可能是同一期岩浆作用的产物。宝山矿区花岗闪长斑岩中锆石的Ce~(4+)/Ce~(3+)比值平均为355,与全球典型的含铜斑岩的Ce~(4+)/Ce~(3+)比值( 300)相似。而大坊矿区花岗闪长斑岩中锆石的δEu平均为0. 48,与宝山岩体δEu平均值(0. 42)相近,指示二者具有相对较高的氧逸度,均为与铜金多金属矿化有关的斑岩体。锆石U-Pb年龄、Hf同位素及微量元素特征表明,大坊金矿和宝山铜多金属矿床均与矿区花岗闪长斑岩具有时空及成因联系,共同构成钦杭成矿带中段一套与花岗闪长斑岩有关的Cu(Mo)-Pb-Zn-Au-Ag成矿系统。     

俄罗斯远东岗仁地体金铜矿床地质、地球化学特征及其LA-ICP-MS锆石U-Pb年龄

岗仁地体位于额尔古纳超地体北部边缘,蒙古—鄂霍茨克构造带南部,该区分布着大量的大型、超大型金矿床,这些矿床在成因上与中酸性侵入岩和浅成次火山岩关系密切。岩石地球化学研究表明,花岗闪长岩-闪长岩组合明显富集大离子亲石元素、不相容元素和轻稀土元素,亏损高场强元素和重稀土元素。球粒陨石标准化稀土配分模式为轻稀土元素富集、重稀土元素亏损的右倾型,具有微弱的负Eu异常或基本无Eu异常,无Ce异常,元素地球化学性质反映出花岗闪长岩-闪长岩组岩浆具有壳幔混合的特征,且形成于大陆边缘的火山弧环境。LA-ICP-MS锆石U-Pb测年结果揭示,皮奥涅尔金银矿床含矿闪长玢岩的206Pb/238U年龄加权平均值为113.8±2.0Ma,博尔古利坎铜金钼矿床赋矿二长闪长斑岩的206Pb/238U年龄加权平均值为112.7±2.8Ma,与皮奥涅尔金银矿床和博尔古利坎铜金钼矿床成矿有关的奥列佳花岗闪长岩体的年龄分别为117.2±1.3Ma和117.0±3.6Ma。由此可知,皮奥涅尔金银矿床和博尔古利坎铜金钼矿床形成于燕山早期,与中国黑龙江地区三道湾子金矿、东安金矿等金矿床形成时代一致。     

宁芜北段与梅山铁多金属矿床有关的辉长闪长玢岩的LA-MC-ICP-MS锆石U-Pb定年：对岩浆热液成矿系统时限的约束

梅山铁多金属矿床是宁芜盆地内代表性矿床之一,其Fe-Cu-Au-Mo矿化与辉长闪长玢岩密切相关。本文对含矿辉长闪长玢岩及矿体下部的新鲜辉长闪长玢岩进行LA-MC-ICP-MS锆石U-Pb定年,获得年龄分别为(137.8±1.7)Ma、(141.2±1.0)Ma。因此辉长闪长玢岩形成时间应在138~141 Ma,伴随的Fe-Cu-Au-Mo矿化稍晚,都属于早白垩世,受区域岩石圈伸展和减薄作用制约。根据年代学和地质事实证据,初步认为宁芜盆地早白垩世火山活动从北段开始,火山活动持续时间至少为7~10 Ma。辉长闪长玢岩中古老锆石年龄变化于1898~1903 Ma、1163 Ma和292~296 Ma,时代分别为古元古代、新元古代和早二叠纪,暗示着岩浆上侵过程中基底岩石对岩浆可能有混染作用,表明长江中下游成矿带存在早元古代结晶基底和中—晚元古代褶皱基底的"双层结构"。     

西藏尼木县厅宫、白容铜矿区矿床地质的几个问题

近期钻孔资料揭示,西藏尼木县厅宫铜矿区主要为二长花岗(斑)岩、花岗闪长斑岩、钾长花岗(斑)岩和石英闪长玢岩构成的复式斑岩体,白容铜矿区的容矿岩石为花岗闪长斑岩、闪长玢岩,以及正长斑岩、安山玢岩脉;铜(钼)矿化呈面型分布,含矿斑岩体几乎全岩矿化,与围岩接触带附近矿化强度增强;矿化垂向厚度达数百米,强弱不均,自上而下可分为氧化带、过渡带、原生带;硅化、绢云母化、高岭土化、黄铁矿化等蚀变广泛而强烈.     

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