大兴安岭太平沟钼矿床成矿年代学研究

太平沟钼矿床为大兴安岭地区新发现的斑岩型钼矿床.本文的同位素地质年代学研究获得获得含矿的蚀变二长花岗斑岩的钾长石~(40)Ar-~(39)Ar等时线年龄为127.5±4Ma,花岗斑岩锆石SHRIMP U-Pb年龄为131.5±1.1Ma,矿体辉钼矿Re-Os等时线年龄为129.4±3.9Ma,表明斑岩成矿系统形成于131.5～127.5Ma,与早白垩世区域性燕山期大规模构造-岩浆事件一致.     

豫西沙坡岭钼矿床辉钼矿Re-Os同位素年龄及其地质意义

河南省沙坡岭钼矿床是东秦岭钼矿带东段新发现的热液脉型钼矿床,通过对矿石中5件辉钼矿样品的Re-Os同位素定年,获得125.4 Ma~129.4 Ma的模式年龄,加权平均年龄为127.22 Ma±0.85 Ma,得到一个相关性较好的128.1 Ma±7.1 Ma的等时线年龄,表明沙坡岭钼矿床形成于燕山中晚期。沙坡岭钼矿床辉钼矿的w(Re)高达147.2×10-6~307.8×10-6,与陕西黄龙铺钼矿床中的Re质量分数接近,表明有幔源物质和/或流体参与了成矿过程,暗示沙坡岭钼矿床的形成与中国东部的大规模岩石圈减薄事件有关。沙坡岭钼矿床深部可能存在斑岩型钼矿化,具有较大的找矿潜力。     

赣南园岭寨大型钼矿岩石地球化学、成岩成矿年代学及其地质意义

江西省安远县园岭寨钼矿是南岭地区新发现的大型独立斑岩型钼矿床,矿体主要产出在园岭寨花岗斑岩与寻乌组变质岩的内外接触带中。通过对园岭寨钼矿系统的岩石学、地球化学和成岩成矿时代研究,结果表明,园岭寨花岗斑岩化学成分具有富K2O(6.52%～8.33%)、P2O5(0.17%～0.21%)、过铝质(A/CNK=1.33～1.59),高Mg#(53～68)、贫CaO(0.37%～2.99%)、Na2O(0.27%～1.01%)和K2O/Na2O>1的特征;微量元素以富含Rb,亏损Ba、Sr等大离子亲石元素(LILE)和富含U、Pb、Nd、Zr、Hf等,亏损Nb、Ta、La、Ce、P、Ti等高场强元素(HFSE)为主要特征,Eu负异常不明显(δEu=0.80～0.90),(La/Yb)N=9.27～13.18,轻重稀土分馏明显。结合成因类型判别图解和矿物学特征,园岭寨斑岩为典型的S型花岗岩,以壳源物质的重熔为主,并受一定程度的幔源物质影响。利用LA-MC-ICP-MS锆石U-Pb年龄,获得了花岗斑岩的成岩年龄为165.49±0.59Ma(MSWD=1.4,n=19);利用辉钼矿Re-Os同位素测年法,获得园岭寨钼矿床辉钼矿的结晶年龄为160±1～162.7±1.1Ma,属赣南燕山期第二次钼成矿作用(150～162Ma)。结合区域年代学资料和已知的矿床(点),指出本区进一步找矿工作应集中在中-晚侏罗世-早白垩世Mo、Pb、Zn等矿床的查找上。     

安徽省金寨县沙坪沟钼矿辉钼矿Re-Os年龄——兼论东秦岭-大别山中生代钼成矿作用期次划分

安徽省金寨县沙坪沟钼矿是新发现的超大型斑岩型钼矿床.文章介绍了该矿床的基本地质特征,并对其进行了精确的辉钼矿Re-Os同位素年代学测定.结果表明,沙坪沟钼矿辉钼矿模式年龄为(112.2±1.7)～(113.9±1.7) Ma,加权平均年龄为(113.18±0.54) Ma,MSWD - 0.39;等时线年龄为(113....     

内蒙古半拉山钼矿LA-ICP-MS锆石U-Pb与辉钼矿Re-Os年龄及其成矿动力学背景

内蒙古阿鲁科尔沁旗半拉山钼矿床位于大兴安岭南段,是新发现的中型爆破角砾岩型钼矿床.半拉山钼矿区内流纹岩围岩和花岗斑岩岩脉的LA-ICP-MS锆石U-Pb年龄分别是(157.5±3.3)Ma和(126.3±2.1)Ma,而辉钼矿样品的Re-Os同位素等时线年龄为(136.1±6.6)Ma(MSWD=0.42),表明成矿作...     

内蒙古兴和县曹四夭超大型斑岩钼铅锌金成矿系统年代学及其地质意义

曹四夭斑岩钼矿床位于内蒙古兴和县,是华北克拉通北缘最大的钼矿床。该矿床中部发育斑岩型钼矿体,外围和上部产出热液脉型铅锌金矿体。文章选取1件与斑岩钼矿化共生的绢云母样品进行了40Ar-39Ar定年,获得40Ar-39Ar坪年龄为(144.4±1.2)Ma,相应的39Ar/36Ar-40Ar/39Ar等时线年龄为(146.4±2.2)Ma(MSWD=0.31),将等时线年龄认作绢云母的Ar封闭年龄,表明曹四夭斑岩钼矿化发生在约146 Ma前。选取14件脉型铅锌矿石中的闪锌矿、黄铁矿和磁黄铁矿样品开展了Rb-Sr定年,获得4件闪锌矿的Rb-Sr等时线年龄为(145.1±3.0)Ma(MSWD=0.63);5件黄铁矿的Rb-Sr等时线年龄为(145.2±1.3)Ma(MSWD=0.53);4件闪锌矿、5件黄铁矿和1件磁黄铁矿的Rb-Sr等时线年龄为(145.3±1.0)Ma(MSWD=0.43)。硫化物Rb-Sr定年结果表明曹四夭矿床脉型铅锌矿化形成于约145 Ma前。本次绢云母40Ar-39Ar和硫化物Rb-Sr定年结果表明,曹四夭矿床斑岩型钼矿化和脉型铅锌金矿化为同期产物,两者均形成于晚侏罗世末期,属于同一个斑岩成矿系统。曹四夭矿床硫化物的w(Rb)和w(Sr)分别为0.1867×10~(-6)~1.305×10~(-6)和0.3175×10~(-6)~6.935×10~(-6),Sr同位素初始比值(87Sr/86Sr)i介于0.709 919~0.711 951之间,平均值0.710 952,结合前人获得的辉钼矿Re含量,认为曹四夭矿床的成矿物质主要来源于地壳。     

大别山南麓梨木岭钼矿床辉钼矿Re-Os同位素年龄及地质意义

梨木岭钼矿床是近年来新发现的钼矿,也是目前大别山构造带唯一具有工业意义的中型钼矿床。通过辉钼矿Re-Os同位素年代学测定,获得梨木岭钼矿Ⅰ矿脉5件样品辉钼矿的Re-Os模式年龄为(115.3±1.4)Ma~(118.1±1.5)Ma,加权平均年龄为(116.8±1.3)Ma;等时线年龄为(119.9±6.2)Ma(MSWD=1.6)。Ⅱ矿脉2件辉钼矿Re-Os模式年龄分别为(114.7±1.6)Ma和(117.0±1.4)Ma。两条矿脉中辉钼矿样品的Re-Os模式年龄在误差范围内一致,表明这两条矿脉为早白垩世同期热液产物。梨木岭钼矿床可能为与早白垩世中酸性岩浆活动有关的岩浆热液型矿床。早白垩世大别山钼成矿作用不仅仅局限在北大别的北淮阳构造带,在大别山南麓同样存在该阶段钼成矿作用。     

内蒙古卓资县大苏计钼矿辉钼矿铼-锇同位素定年及其地质意义

内蒙古卓资县大苏计钼矿是近年来华北陆块北缘中西部地区新发现的斑岩型钼矿床。通过对含辉钼矿石英斑岩中采集的辉钼矿样品进行铼-锇同位素年龄测定,获得铼-锇等时线年龄为(222.5±3.2)Ma,模式年龄变化于(222.1±3.2)Ma～(224.6±3.4)Ma,表明辉钼矿形成时代为晚三叠世。该铼-锇同位素年龄值指示华北陆块北缘存在着印支期成矿地质作用,对在该地区寻找印支期钼多金属矿床具有重要的指导意义。     

河北涞源大湾锌钼矿床锆石U-Pb和辉钼矿Re-Os年龄及其地质意义

大湾斑岩-矽卡岩型锌钼矿床地处太行山北段成矿带中,是该段重要的金属矿床之一.五台群板峪口组和长城系高于庄组为主要赋矿围岩,锌钼矿体主要赋存在流纹斑岩体内及斑岩与围岩接触部位.文章对大湾矿床内2件赋矿流纹斑岩进行LA-ICP-MS锆石U-Pb年代测定,获得206Pb/238U年龄加权平均值分别为(137.1±0.9)Ma(MSWD=0.56,n=24)和(136.8±1.2)Ma(MSWD=0.40,n=22);对矿区4件辉钼矿样品进行Re-Os定年,得到加权平均年龄为(136.5±1.0)Ma,等时线年龄为(136.1±2.3)Ma,在误差范围内成岩成矿时代一致,显示大湾锌钼矿床形成于早白垩世.大湾矿床中辉钼矿的w(Re)为5.816～16.484μg/g,反映了矿床成矿物质来源具有壳幔混合特征.区内流纹斑岩和蚀变体系为进一步找矿勘查的有利标志.     

陕西洛南县石家湾钼矿Re-Os同位素年龄及地质意义

陕西石家湾钼矿床位于东秦岭成矿带西段黄龙铺地区,钼矿化呈细脉-网脉状分布于花岗斑岩体及其围岩中,与矿化有关的围岩蚀变有钾长石化、硅化、绢云母化,属斑岩型矿床.在矿床中选取不同矿化类型的辉钼矿样品,进行了Re～Os同位素定年,获得模式年龄变化范围为143.1±2.1～145.1±2.2 Ma之间,其加权平均年龄(144.0±1.1 Ma,MSWD=0.91)、等时线年龄(145.4±2.1 Ma,MSWD=0.83)与石家湾斑岩体的成岩年龄(141.4±0.6Ma)相近,说明成岩成矿作用发生在晚侏罗世一早白垩世.综合辉钼矿中Re的含量、硫同位素以及相关岩体的源区特征等多方面证据认为,石家湾斑岩型钼矿的成矿物质主要来自于下地壳,并混有少量幔源成分.     

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.     

Late Wuchiapingian (Late Dzhulfian,early Late Permian) limestone olistolites within the Tertiary flysch of Glypia Unit (Mount Parnon,central–eastern Peloponnesus,Greece)

Some olistolites reworked in a Tertiary flysch of Mount Parnon (Peloponnesus, Greece) exhibit a Late Permian assemblage, dominated by Paradunbarula (Shindella) shindensis, Hemigordiopsis cf. luquensis and Colaniella aff. minima. This association corresponds to the Late Wuchiapingian (=Late Dzhulfian), a substage whose algae and foraminifera are generally little known. Contemporaneous limestones crop out in the middle part of the Episkopi Formation in Hydra, but they are rather commonly reworked in Mesozoic and Cainozoic sequences. The palaeobiogeographical affinities shared by the foraminiferal markers of Greece, southeastern Pamir, and southern China, are very strong (up to the specific level), and are congruent with the Pangea B reconstructions. To cite this article: E. Skourtsos et al., C. R. Geoscience 334 (2002) 925–931.     

PALEONTOLOGY

正20141596 Liu Yunhuan(School of Earth Sciences and Resources,Chang’an University,Xi’an 710054,China);Shao Tiequan Early Cambrian Quadrapyrgites Fossils of Xixiang Boita in Southern Shaanxi Province(Journal of Earth Sciences and Environment,ISSN1672-6561,CN61-1423/P,35(3),2013,p.39-43,3 illus.,20 refs.)     

GEOCHEMICAL EXPLORATION

正20141719 Chen Zhijun(State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Wuhan 430074,China);Chen Jianguo Automated Batch Mapping Solution for Serial Maps:A Case Study of Exploration Geochemistry Maps(Journal of Geology,ISSN1674-3636,CN32-1796/P,37(3),2013,p.456-464,2 illus.,2 tables,10 refs.)     

MICROPALAEONTOLOGY

正20140962 Chen Fenning(Xi’an Institute of Geology and Mineral Resources,Xi’an710054,China);Chen Ruiming Late Miocene-Early Pleistocene Ostracoda Fauna of Gyirong Basin,Southern Tibet(Acta Geologica Sinica,ISSN0001-5717,CN11-1951/P,87(6),2013,p.872-886,6illus.,56refs.)     

PETROLOGY

正1.IGNEOUS PETROLOGY20142008Cai Jinhui(Wuhan Center,China Geological Survey,Wuhan 430205,China);Liu Wei Zircon U-Pb Geochronology and Mineralization Significance of Granodiorites from Fuzichong Pb-Zn Deposit,Guangxi,South China(Geology and Mineral Resources of South China,ISSN1007-3701,CN42-1417/P,29(4),2013,p.271-281,7illus.,     

ENVIRONMENTAL GEOLOGY

正20141205Cheng Weiming(State Key Laboratory of Resources and Environmental Information System,Institute of Geographic Sciences and Natural Resources Research,CAS,Beijing 100101,China);Xia Yao Regional Hazard Assessment of Disaster Environment for Debris Flows:Taking Jundu Mountain,Beijing as an     

PROSPECTING EXPLORATION

正20141266Fan Chaoyan(Guangdong Provincial Key Laboratory of Mineral Resources and Geological Processes,Guangzhou 510275,China);Wang Zhenghai On Error Analysis and Correction Method of Measured Strata Section with Wire Projection Method(Journal of