南岭诸广山北体复式花岗岩锆石SHRIMP U-Pb年龄及多期岩浆活动

诸广山复式花岗岩基位于湘、赣、粤三省交界处,是南岭花岗岩的重要组成部分,由南体和北体组成,出露面积大于5000 km2,形成于加里东期、印支期、燕山期3个时代。通过对诸广山北体3期花岗岩锆石SHRIMP U-Pb定年,结果表明,加里东期花岗闪长岩锆石SHRIMP U-Pb年龄为(414.5±4.5)Ma(n=13,MSWD=0.52)、(417.3±4.8)Ma(n=12,MSWD=0.84),形成于晚志留世末。印支期黑云母二长花岗岩锆石SHRIMP U-Pb年龄(207.5±2.7)Ma(n=10,MSWD=1.6),形成于晚三叠世末。燕山期二云母二长花岗岩锆石SHRIMP U-Pb年龄(148.2±1.7)Ma(n=13,MSWD=0.93),形成于晚侏罗世。该成果为南岭地区构造-岩浆演化及成矿作用研究,提供了重要的花岗岩年代学依据。     

浙江安吉多金属矿区坞山关杂岩体锆石LA ICP MS U Pb年龄、地球化学特征及地质意义

安吉港口多金属矿床在成因上与坞山关杂岩体密切相关,该杂岩体包括黑云母二长花岗岩、钾长花岗岩、花岗闪长岩和细粒花岗岩。本文采用岩相学、CL和LA-ICP-MS等方法对前三套岩石单元中的锆石进行了成因矿物学、微区微量元素和U-Pb年代学特征等相关研究。年代学结果显示,杂岩体大致形成于晚侏罗世—早白垩世,按前述排列顺序,三岩石单元成岩年龄分别为141.0±1.4Ma(n=13,MSWD=1.3),138.1±1.0Ma(n=14,MSWD=0.92)和137.0±1.8Ma(n=13,MSWD=1.9)。研究过程中发现的年龄为518±9Ma和624±9Ma的继承锆石,暗示杂岩体成岩过程中有晋宁晚期和加里东早期古老地壳物质的熔融或同化混染。锆石Ti温度记显示,杂岩体中黑云母二长花岗岩、花岗闪长岩锆石结晶温度基本一致,均值分别为657℃和653℃,钾长花岗岩锆石结晶温度略高,均值为698℃。区域构造环境、岩体被动侵位、构造张性和张剪性特征表明,矿区在约141～137Ma前后已处于拉张—伸展构造背景之下,杂岩体及其相关成矿作用受该环境控制。本次研究及野外调研结果表明,杂岩体与矿区多金属矿床具有密切的时空关系。浙江淳安铜山锡矿、安吉多金属矿床成岩成矿数据表明,钦—杭成矿带东段在晚侏罗世—白垩世约148～134Ma还存在一期成岩成矿作用。     

赣西蒙山岩体地球化学、锆石U-Pb年龄、Hf同位素特征及地质意义北大核心CSCD

以赣西地区蒙山岩体为研究对象,通过对该岩体地球化学、锆石U-Pb年龄及Hf同位素的研究,探讨其岩浆物质来源及构造背景。该岩体经历了印支期、燕山期岩浆侵入活动,形成六种岩石类型,LA-ICP-MS锆石U-Pb年龄分别为224.0±2.10 Ma(n=19,MSWD=1.9)、223.0±2.20 Ma(n=21,MSWD=2.6)、222.0±2.80 Ma(n=21,MSWD=2.7)、220.0±1.90 Ma(n=16,MSWD=1.5)、217.0±3.70 Ma(n=8,MSWD=1.8)、142.0±0.98 Ma(n=21,MSWD=1.4),表明岩体经历了印支期、燕山期两期岩浆活动。印支期花岗质岩石地球化学具高硅富钾、准铝-过铝质特征;微量元素富集高场强元素Zr、Hf、Th、U和稀土元素La、Ce、Sm、Nd、Y,明显亏损Rb、Ba、Sr、Ti、P;稀土元素分馏程度不高,δEu介于0.03~0.15,具强Eu负异常,Ce异常不明显,稀土配分曲线呈“V”型;为同源岩浆演化的特点。CaO/Na_(2) O比值<0.3、Rb/Sr>5,岩石二阶段模式年龄T DM2主体介于868~1465 Ma,为中-新元古代,εHf(t)对应的T DM2值显示,岩体物源起源于成熟地壳,后期有大量新生地壳物质的加入,表明岩石来源于含水矿物(如白云母、绿帘石/黝帘石)的脱水反应导致成熟度高地壳物质的熔融而形成。在花岗岩构造环境判别图上,投于碰撞大地构造背景上的花岗岩和造山后花岗岩类(POG)区域,锆石U-Pb年龄表明成岩时段滞后于印支运动高峰期(258~243 Ma),为受印支运动造成华南地壳加厚滞后,地壳进入伸展阶段,减压熔融形成的花岗质岩浆。     

内蒙古赵井沟铌钽矿床燕山期成矿:来自LA-MC-ICP-MS独居石、锆石U-Pb和黑云母40Ar-39Ar年龄的证据

内蒙古武川县赵井沟铌钽矿是新近取得勘查突破的一例大型铌钽矿床.矿体赋存岩石为含天河石钠长花岗岩,其次为花岗细晶岩、云英岩及天河石花岗伟晶岩.运用LA-MC-ICP-MS法对矿区钠长花岗（细晶）岩脉、正长花岗岩中的独居石、锆石进行了U-Pb同位素年龄测定,同时对石英-黑云母脉中的黑云母进行了40Ar-39Ar定年.4件独居石的LA-MC-ICP-MS U-Pb年龄分别为124±2 Ma（MSWD=2.9,n=27）、124±3 Ma（MSWD=2.0,n=46）、121±1 Ma（MSWD=3.3,n=43）和124±2 Ma（MSWD=3.2,n=12）,1件锆石的LA-MC-ICP-MS U-Pb年龄为125±1 Ma（MSWD=1.6,n=18）;黑云母40Ar-39Ar坪年龄为133.84±0.79 Ma（MSWD=3.31）,40Ar/36Ar-39Ar/36Ar等时线年龄为134.55±0.79 Ma（MSWD=1.93）,反等时线年龄为134.58±0.80 Ma（MSWD=1.99）,这些年龄限定赵井沟铌钽矿形成于早白垩世.综合分析表明,燕山期是内蒙古地区重要的铌钽成矿期,赵井沟铌钽矿是燕山期伸展体制下构造岩浆活动的产物.      

青海石底泉地区宗务隆构造带花岗闪长岩LA-ICP-MS锆石U-Pb年龄及其地质意义

对德令哈市石底泉地区宗务隆构造带内花岗闪长岩进行了锆石U-Pb测年和岩石地球化学分析。岩石地球化学分析结果显示,其具有岛弧或活动大陆边缘花岗岩的属性,原岩可能为新元古代早期(870.0±4.5Ma左右)硅铝地壳或地壳物质熔融的产物,它们的形成与板块的俯冲作用有关LA-ICP-MS锆石U-Pb测年显示2组年龄,分别为870.0±4.5Ma和443.3±2.3Ma。其中870.0±4.5Ma代表源区继承锆石的年龄,反映了新元古代时期的构造岩浆事件;443.3±2.3Ma代表花岗闪长岩岩浆锆石的结晶年龄,即花岗闪长岩侵位于晚奥陶世。综合分析可以确定,宗务隆构造带内花岗闪长岩与柴达木盆地北缘加里东期的板块汇聚碰撞造山作用有关,证实了宗务隆构造带内岩体形成时代并非全部是海西期一印支期。     

西大别芳畈花岗岩锆石U-Pb年龄、地球化学特征及其构造意义

本文通过对西大别大悟芳畈地区黑云母花岗岩和石英正长岩花岗岩两种岩体的地球化学分析及U-Pb同位素测试,得到如下认识:黑云母花岗岩和石英正长岩花岗岩总体特征相似,主量元素表现为高SiO2(平均77.2%)、过铝质(A/CNK指数在1.03~1.13),碱度率在5.43~7.23,属碱性系列;ΣREE平均62.4×10-6,(Ce/Yb)N均值为0.67,(La/Yb)N均值为0.97,呈现平缓仅Eu亏损(δEu均值0.20)的"海鸥型";大离子亲石元素Rb、Th、U、K等相对富集,高场强元素Nb、Ta、Sr、Ti等呈明显的负异常,说明岩浆源岩以陆壳成分为主;Ga/Al均值为3.16,Zr+Nb+Ce+Y均值为578;锆石饱和温度为833~877℃,稀土元素饱和浓度温度为773~862℃,表明初始岩浆温度较高。上述特征说明,芳畈花岗岩为典型的A型花岗岩,形成于中上地壳的板内伸展背景。用LA-ICPMS测得的黑云母花岗岩中锆石的U-Pb年龄为773.0±1.6 Ma(MSWD=0.96,n=33),石英正长花岗岩形成的年龄为759.8±2.3 Ma(MSWD=1.6,n=28),表明其形成于新元古代洋陆俯冲的构造背景,是这一时期大陆边缘弧岩浆作用的产物。芳畈花岗岩体形成时代早于其外围地层,是经后期构造改造形成的混杂岩带,其岩浆作用与岩体外围的铜成矿作用无直接联系。     

福建省泰宁县何宝山金矿床长兴岩体锆石LA-ICP-MS U-Pb年龄及其地质意义

长兴钾长混合花岗岩体与何宝山金矿床的成矿作用关系密切。何宝山金矿床的成矿作用表现出多期次、多阶段的特点,加里东晚期长兴岩体的侵入活动促进了金矿床成矿物质早期的迁移和富集,印支晚期—燕山早期的构造-岩浆活动叠加成矿。文中对区内加里东期主要侵入岩体进行了锆石LA-ICP-MS U-Pb同位素定年研究,得出长兴岩体的成岩年龄为(437.1±1.3)Ma,黑云母石英闪长岩成岩年龄为(436.6±1.1)Ma,黑云母花岗闪长岩脉成岩年龄为(427.1±1.4)Ma,从而确定金矿床成矿期上限,为进一步成矿作用研究提供科学依据。     

滇西北休瓦促钨钼矿区复式岩体地质及其成矿特征——来自年代学、氧逸度和地球化学的约束

休瓦促钨钼矿床位于义敦岛弧南段的香格里拉北部,目前已达中-大型。该区发育由两期岩体(晚三叠世的黑云母花岗岩和晚白垩世的斑状二长花岗岩)叠加而成的复式岩体,而该矿区钨钼矿形成于82~86Ma。然而,两期岩体间关系,以及晚三叠世岩体对矿床的形成有怎样的贡献,目前未有报道。笔者通过对两期岩体形成时间及其地球化学特征的研究,从成岩年代学、岩浆氧逸度等方面探究上述问题,并揭示两期岩体的成矿特征,为找矿实践提供一定的参考依据。研究表明,黑云母花岗岩结晶年龄为211.7±2.6Ma,SiO_2偏高(69.48%~73.73%),属高钾的钾玄质系列,偏铝质,富集轻稀土元素和大离子亲石元素而亏损重稀土元素以及高场强元素Nb、Sr、Ti等,有微弱的负Eu异常,岩浆氧逸度相对较高(fO_2=-19.4~-9.1,平均-13.7);斑状二长花岗岩结晶年龄为76.8±3.8Ma,且有一颗锆石核部的年龄值为219±2.6Ma,该岩体与前者有相似的地球化学特征,SiO_2高(67.35%~75.65%),属偏铝质的钾玄质系列,ΣREE较高,高于黑云母花岗岩,铕负异常明显大于前者,岩浆氧逸度相对较低(fO_2=-30.4~-18.2,平均-23.4)。据此,结合休瓦促矿区断层发育情况,提出矿区内两期岩体以近南北向F_4为界呈断层接触关系,北西向走滑断层(F_1-F_3)为控矿构造。本文认为,晚期斑状二长花岗岩对早期黑云母花岗岩具有一定的继承性关系,黑云母花岗岩来源于晚三叠世甘孜-理塘洋向西俯冲环境下地壳的部分熔融,岩浆富水、氧逸度高,利于形成Cu-Au矿床,且在找矿实践中得到部分验证;斑状二长花岗岩来源于加厚下地壳的部分熔融,岩浆贫水、氧逸度低于黑云母花岗岩,与W-Mo矿床相关。即,晚白垩世岩浆热液沿矿区断裂-裂隙系统运移,继承和发展早期岩浆活动,形成脉状细晶岩和W-Mo矿床。     

闽西南虎岗地区晚中生代花岗岩LA-MC-ICP-MS锆石U-Pb年龄、地球化学特征及地质意义

选取福建虎岗地区灌洋和增坑二个岩体进行LA-MC-ICP-MS锆石U-Pb测年.增坑细粒二长花岗岩岩体单颗粒锆石U-Pb年龄为145.4±18.2～151.4±7.9 Ma,加权平均值为147.98±0.86 Ma(可信度95%,MSWD=0.62).灌洋中细粒黑云母二长花岗岩岩体单颗粒锆石年龄为141.2±4.1 ～ 145.5±1.9Ma,加权平均值为143.0±1.1Ma(可信度95%,MSWD=0.41).二岩体形成于挤压碰撞的构造环境,微量元素含量表明,岩浆分异作用较强,酸性程度较高,n(A12O3) ＞n(CaO) +n(Na2O) +n(K2O),且有较高的Rb/Sr和Rb/Nb比值,低含量的Ni、Cr含量和右倾型的稀土元素模式,表明岩体岩浆起源于大陆地壳中沉积的源岩,属于铝过饱和S型花岗岩.增坑和灌洋岩体形成年代都为晚侏罗世(燕山中晚期),且为铁铜多金属矿成矿提供了物质基础.     

内蒙古道伦达坝铜钨锡矿床LA-ICP-MS锆石和锡石U-Pb年龄及其地质意义

道伦达坝矿床位于大兴安岭南段,是一个铜钨锡矿床,其铜、钨、锡储量均达中型。矿体呈脉状,主要产于二叠系砂板岩中的断裂破碎带中,华力西期黑云母花岗岩中的断裂破碎带中亦赋存有矿体。文章选取2件石英-萤石-白云母-电气石-锡石-黑钨矿阶段的矿石样品对其中的进行了LA-ICP-MS U-Pb定年,获得2件样品的~(207)Pb/~(206)Pb-~(238)U/~(206)Pb谐和年龄分别为(134.7±6.6)Ma(MSWD=1.4)和(136.8±7.4)Ma(MSWD=1.7),~(206)Pb/~(207)Pb-~(238)U/~(207)Pb等时线年龄分别为(132±12)Ma(MSWD=0.76)和(135±13)Ma(MSWD=0.9)。锡石定年结果表明,道伦达坝矿床形成于早白垩世。对矿区外围张家营子岩体中的斑状细粒花岗岩进行了LA-ICP-MS锆石U-Pb测年,获得的~(206)Pb/~(238)U加权平均年龄为(135±1)Ma(MSWD=1.3),该岩体的形成年龄与道伦达坝矿床的成矿年龄在误差范围内一致。本次定年结果表明道伦达坝矿床形成于早白垩世,与同期的花岗质岩浆活动有密切的成因联系,该矿床属于与花岗岩有关的岩浆热液脉型矿床。     

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