小秦岭金（钼）矿床辉钼矿铼_锇定年及其地质意义

最近在河南灵宝小秦岭地区大湖金矿及其附近的泉家峪含金石英脉中发现了具有工业价值的钼矿化。为了研究小秦岭金矿集中区钼矿的成矿时代,笔者选取大湖金(钼)矿床及泉家峪石英脉型金钼矿体中的辉钼矿进行了Re-Os法同位素定年,在大湖钼金矿石中获得3个辉钼矿样品的Re-Os模式年龄,分别为(223.0±2.8)Ma、(223.7±2.6)Ma和(232.9±2.7)Ma;泉家峪钼金矿石中2个辉钼矿样品的Re-Os模式年龄分别为(129.1±1.6)Ma和(130.8±1.5)Ma。这些年龄数据表明,该区的成矿作用不仅发生于燕山期,而且还发生在印支期。与金堆城、黄龙铺等典型钼矿床不同,大湖和泉家峪矿床中辉钼矿含铼很低,可能表明它们的成矿物质来自壳源。     

江西广昌新安钼矿床地质特征及其铼-锇同位素测年

广昌新安钼矿是武夷山西坡中段新发现的斑岩型钼矿床。文章概要地介绍了该矿床的地质特征,并利用Re-Os同位素定年方法对新安钼矿体中的辉钼矿进行了成矿年代的测定,获得辉钼矿同位素的模式年龄为(166.7±2.3)Ma～(169.5±2.4)Ma,计算出等时线年龄为(168.3±1.7)Ma,表明其钼矿成矿作用发生于燕山早期,属于华南中生代大规模成矿作用第一阶段的产物。矿床成矿时代的精确厘定,说明该区在燕山期大规模钨锡成矿作用之前(165～150 Ma),可能存在一期独立的钼成矿作用。区域钼矿床年龄数据统计表明,本区至少存在三期独立的钼成矿作用,分别集中在130～140 Ma、150～160 Ma和165～170 Ma,意味着本区钼成矿作用经历了漫长的演化过程,这对区域岩浆岩活动及其成矿作用研究和找矿工作具有指导意义。     

河南商城县汤家坪钼矿辉钼矿铼_锇同位素年龄及地质意义

为查明商城县汤家坪大型钼矿床形成的时代,建立钼多金属矿成矿模式,利用电感耦合等离子体质谱仪对汤家坪等3个钼矿床的7件辉钼矿样品进行了Re-Os同位素年龄测定,获得汤家坪钼矿床辉钼矿Re-Os等时线年龄为(113.1±7.9)Ma,准确厘定其成矿时代为早白垩世;测得天目沟钼矿床辉钼矿Re-Os同位素模式年龄为(121.6±2.1)Ma,大银尖钼矿床辉钼矿Re-Os同位素模式年龄为(122.1±2.4)Ma,初步确定大别山钼成矿带的成矿年龄大约在(122.1±2.4)～(113.1±7.9)Ma之间。结合前人研究成果,认为大别山北麓钼成矿作用的地球动力学背景为燕山晚期大别造山带在伸展机制下岩石圈减薄,中国中东部区域构造-动力体制由近EW向构造为主向近SN向构造为主的大转换时期。     

内蒙古红花尔基钨钼矿云英岩化白云母Ar-Ar定年及其地质意义

红花尔基钨多金属矿是近年在大兴安岭中北部地区发现的一处大型钨多金属矿床,主要矿化蚀变为云英岩化、绢英岩化,主要有用金属矿物为白钨矿和辉钼矿,岩体内辉钼矿与白钨矿有上钼下钨的带状分布特点,地质特征显示该矿床为一高温热液型钨(钼)矿床。为准确限定成矿热液活动时间,本文对矿区典型蚀变矿物——云英岩化蚀变带白云母进行Ar-Ar同位素定年,获得Ar-Ar坪年龄为174.4±1.2 Ma,等时线年龄为173.2±4.3 Ma。根据矿区云英岩化带与钨钼矿化带空间上重合和密切共生的关系,可知白云母的形成是与白钨矿、辉钼矿形成同源、同时,且辉钼矿Re-Os年龄(176.8±2.2 Ma)与Ar-Ar年龄在误差范围内具有一致性,该年龄代表了钨钼矿热液成矿时代。结合野外地质特征及锆石U-Pb、辉钼矿Re-Os年龄,进一步限定该矿床成矿时代为早中侏罗世,属燕山期构造岩浆活动的产物。     

浙江省桐村钼矿床Re-Os同位素年龄及地质意义

浙江桐村斑岩型钼矿床位于钦杭成矿带东段,紧邻赣东北成矿带,矿床的形成与燕山早期侵入的同熔型花岗岩有关,含矿岩体的成岩年龄165 ～168Ma.辉钼矿矿石呈浸染状产于岩体内部或岩体与围岩的接触带.本文首次对矿床中3件辉钼矿样品进行了Re-Os同位素年代学研究,测得辉钼矿的等时线年龄为162.2Ma±1.3 (MSWD =0.006),代表了成矿年龄.成矿成岩年龄具有一致性,矿床成因类型为斑岩-矽卡岩型钼(铜)矿床.     

黑龙江鹿鸣斑岩型钼矿床Re-Os同位素定年及其地质意义

黑龙江鹿鸣钼矿床是近年来新发现的特大型钼矿床,矿体呈浸染状赋存于燕山早期的二长花岗岩中,属典型的斑岩型钼矿床。笔者对鹿鸣钼矿床的辉钼矿进行了Re-Os同位素测试分析,结果显示:辉钼矿中Re含量为11.896～15.714μg/g,矿床的成矿物质来源为壳幔混合源,以壳源为主;Re-Os模式年龄为(180.2～185.9)Ma,加权平均年龄为(183.4±2.2)Ma。结合最新的赋矿围岩成岩年龄,显示成矿与成岩同时或稍晚于成岩,即鹿鸣钼矿床形成于早侏罗世,为小兴安岭—张广才岭成矿带燕山早期大规模构造-岩浆-成矿事件的产物,成矿与古太平洋板块的俯冲有关。     

秦岭造山带秋树湾铜钼矿床辉钼矿Re-Os定年及其地质意义

秋树湾铜钼矿床是秦岭造山带东段最大的斑岩-夕卡岩型铜钼矿床,通过对矿石中6个辉钼矿样品的 Re-Os 同位素分析,得到了145.57±1.80～147.98±2.21Ma 的模式年龄(平均为146.42±1.77Ma)及一个相关性很好的等时线年龄147±4Ma,表明秋树湾铜钼矿床形成于晚侏罗世,与其以北的华北克拉通南缘的主要斑岩型钼矿床及位于扬子克拉通北缘的长江中下游铁铜矿床的大规模成矿时间一致,是中国东部中生代第2期大规模成矿作用的产物。秋树湾铜钼矿床辉钼矿的含铼量平均达151.8×10~(-6),明显高于华北克拉通南缘钼矿带同期形成的钼矿床(16.13×10~(-6)～28.09×10~(-6)),认为主要是由于两者成矿元素 Cu/Mo 比值的不同造成的;结合矿石硫同位素特征,认为矿床的物质主要来源于下地壳。     

东秦岭南泥湖钼（钨）矿田Re—Os同位素年龄及其地质意义

位于华北克拉通南缘东秦岭钼矿带的南泥湖为一超大型夕卡岩斑岩型钼(钨)矿田,本研究采用电感耦合等离子体质谱仪法对南泥湖钼矿田三个矿床6件辉钼矿进行了Re-Os同位素年龄测定,获得南泥湖矿床的辉钼矿Re-Os模式年龄为141.8±2.1 Ma;三道庄矿床的辉钼矿Re-Os模式年龄为144.5±2.2～145.0±2.2Ma,平均为145.0±2.2 Ma;上房沟矿床的辉钼矿Re-Os模式年龄为143.8士2.1～145.8±2.1 Ma,平均为144.8±2.1 Ma;6件样品的等时线年龄为141.5±7.8 Ma(2σ),准确厘定了成矿时间.Re-Os同位素还表明:南泥湖钼矿的成矿物质来源以下地壳成分为主,但混有少量地幔组分.南泥湖钼矿是在中国东部中生代构造体制大转换中形成,属于中国东部中生代大规模成矿作用的一部分.     

河南汝阳地区竹园沟钼矿地质特征、成矿时代及地质意义

位于东秦岭钼成矿带内的河南汝阳钼铅锌多金属矿田是国内近几年发现的大型矿床集中区,区内发育东沟超大型斑岩钼矿床、竹园沟大型钼矿床和老代仗沟、西灶沟、王坪西沟等大型铅锌矿床。介绍了竹园沟大型钼矿床的地质特征,并利用Re-Os同位素定年方法对竹园沟钼矿体中的辉钼矿进行了成矿年代的测定,获得辉钼矿同位素的模式年龄为(122.2±2.3～119.6±2.2)Ma,平均为120.9Ma±2.3Ma。该成矿年龄显示竹园沟钼矿的成矿时代与汝阳南部其他钼铅锌等多金属矿床的形成时代相近,表明汝阳南部钼铅锌多金属成矿带成岩成矿年龄(120～110Ma)的一致性,均形成于统一的地球动力学背景,即中生代晚期中国东部岩石圈大规模伸展时期的板内拉张环境。     

赣南雷公嶂钼矿床辉钼矿Re-Os年龄及其地质意义

雷公嶂钼矿床是赣南地区新发现的一座具中型钼矿找矿前景的独立钼矿床,成矿特征明显区别于赣南已发现的与钨多金属共(伴)生的钼矿床。为确定矿床成矿时代,文章利用高精度ICP-MS辉钼矿Re-Os同位素测年技术,首次获得了雷公嶂钼矿床的辉钼矿Re-Os同位素加权平均模式年龄,为(156.3±1.0)Ma,等时线年龄为(156.9±3.6)Ma,证实了矿床成岩与成矿作用同时发生,形成于南岭地区燕山早期中晚侏罗世(165～150 Ma)。矿床中辉钼矿的w(Re)为6.104×10^-6～13.974×10^-6,平均为8.507×10^-6,结合矿床地质特征和成矿岩体主量元素及Hf同位素等证据,文章认为成矿物质来自地壳,没有地幔物质加入。结合赣南地区成岩与成矿年代学资料,文章认为区内钨钼多金属矿床形成于华南中生代岩石圈大规模伸展-减薄的地球动力学背景。     

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.     

Définition d'une limite multicritère ; stratigraphie du passage Campanien–Maastrichtien du site géologique de Tercis (Landes,SW France)Definition of a multi-criteria boundary; stratigraphy of the Campanian–Maastrichtian interval of the geological site at Tercis (Landes,SW France)

Lithostratigraphy, physicochemical stratigraphy, biostratigraphy, and geochronology of the 77–70 Ma old series bracketing the Campanian–Maastrichtian boundary have been investigated by 70 experts. For the first time, direct relationships between macro- and microfossils have been established, as well as direct and indirect relationships between chemo-physical and biostratigraphical tools. A combination of criteria for selecting the boundary level, duration estimates, uncertainties on durations and on the location of biohorizons have been considered; new chronostratigraphic units are proposed. The geological site at Tercis is accepted by the Commission on Stratigraphy as the international reference for the stratigraphy of the studied interval. To cite this article: G.S. Odin, C. R. Geoscience 334 (2002) 409–414.     

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.)