2.3 Ga Magmatism and 1.94 Ga Metamorphism in the Xiatang Area,Southern Margin of the North China Craton——Evidence from Whole-rock Geochemistry and Zircon Geochronology and Hf Isotope

本文报道了华北克拉通南缘豫西鲁山下汤地区古元古代片麻状花岗岩和黑云角闪斜长片麻岩的全岩地球化学和锆石SHRIMP U-Pb年龄和Hf同位素组成.岩石呈包体形式存在于中元古代花岗岩中.片麻状花岗岩具深熔特征,岩浆锆石年龄为2.30 Ga;岩石高SiO2和K2O,低∑FeO、MgO和CaO,具稀土总量较高(∑REE=165.8×10-6)、轻重稀土分离较强[(La/Yb)n=37.8]及弱负铕异常(Eu/Eu(*)=0.76)的稀土模式;εNd(t)(t=2.30 Ga)=-0.75; tDM(Nd) =2.66 Ga.黑云角闪斜长片麻岩变质原岩为辉长闪长岩,捕获锆石年龄为2.25 Ga;岩石低SiO2 和MgO,高Al2O3和P2O5,具稀土总量高(∑REE=373.4×10-6)、轻重稀土分离不强[ (La/Yb)n=9.4]及较强负铕异常( Eu/Eu*=0.44)的稀土模式;εNd(t)(t=2.25 Ga)=-1.21;tDM(Nd) =2.75 Ga.片麻状花岗岩和黑云角闪斜长片麻岩都记录了1.94 Ga变质锆石年龄.片麻状花岗岩的岩浆锆石组成域的εHf(t)(t=2.30 Ga)=-6.71～0.38,tDMI(Hf) =2627 ～2910 Ma,tDM2(CC)(Hf)=2823 ～ 3255 Ma.黑云角闪斜长片麻岩的捕获锆石组成域的εHf(t)(t=2.25 Ga)=-19.58～ -1.73,tDM1 (Hf) =2664～3360 Ma,tDM2(CC)(Hf)=2968 ～4011 Ma.结合前人资料,得出如下结论:华北克拉通南缘豫陕晋结合部地区存在—规模较大的约2.3 Ga地质体分布区;华北克拉通南缘很可能存在规模巨大的＞2.7 Ga基底;中部造山带与孔兹岩带具有类似的古元古代晚期构造热事件演化历史.     

华北克拉通南缘豫西下汤地区2.3 Ga岩浆作用和1.94 Ga变质作用

本文报道了华北克拉通南缘豫西鲁山下汤地区古元古代片麻状花岗岩和黑云角闪斜长片麻岩的全岩地球化学和锆石SHRIMP U-Pb年龄和Hf同位素组成。岩石呈包体形式存在于中元古代花岗岩中。片麻状花岗岩具深熔特征,岩浆锆石年龄为2.30Ga;岩石高SiO2和K2O,低ΣFeO、MgO和CaO,具稀土总量较高(ΣREE=165.8×10-6)、轻重稀土分离较强[(La/Yb)n=37.8]及弱负铕异常(Eu/Eu*=0.76)的稀土模式;εNd(t)(t=2.30Ga)=-0.75;tDM(Nd)=2.66Ga。黑云角闪斜长片麻岩变质原岩为辉长闪长岩,捕获锆石年龄为2.25Ga;岩石低SiO2和MgO,高Al2O3和P2O5,具稀土总量高(ΣREE=373.4×10-6)、轻重稀土分离不强[(La/Yb)n=9.4]及较强负铕异常(Eu/Eu*=0.44)的稀土模式;εNd(t)(t=2.25Ga)=-1.21;tDM(Nd)=2.75Ga。片麻状花岗岩和黑云角闪斜长片麻岩都记录了1.94Ga变质锆石年龄。片麻状花岗岩的岩浆锆石组成域的εHf(t)(t=2.30Ga)=-6.71～0.38,tDM1(Hf)=2627～2910Ma,tDM2(CC)(Hf)=2823～3255Ma。黑云角闪斜长片麻岩的捕获锆石组成域的εHf(t)(t=2.25Ga)=-19.58～-1.73,tDM1(Hf)=2664～3360Ma,tDM2(CC)(Hf)=2968～4011Ma。结合前人资料,得出如下结论:华北克拉通南缘豫陕晋结合部地区存在一规模较大的约2.3Ga地质体分布区;华北克拉通南缘很可能存在规模巨大的>2.7Ga基底;中部造山带与孔兹岩带具有类似的古元古代晚期构造热事件演化历史。     

湘东邓阜仙二云母花岗岩锆石U-Pb年代学及地球化学研究

邓阜仙花岗岩体位于湖南茶陵县东北部,是一个由黑云母花岗岩、二云母花岗岩和白云母花岗岩组成的复式岩体。其中,二云母花岗岩与钨成矿关系最为密切。锆石LA-ICP-MS U-Pb同位素定年测得二云母花岗岩的加权平均年龄为154.4±2.2 Ma(MSWD=5.6,n=20),为燕山早期侵位。岩石地球化学研究表明,邓阜仙二云母花岗岩具有高硅、富碱、贫镁铁、强过铝质和高分异的特点。花岗岩相对富集大离子亲石元素Cs、Rb、K和高场强元素Th、U、Pb,亏损Ba、Sr和Ti等,稀土总量偏低(ΣREE平均值为90.59×10-6),轻稀土相对富集(LREE/HREE比值平均为9.97),铕负异常显著(δEu平均值为0.34),稀土元素配分模式呈右倾型。根据区域地质和花岗岩地球化学特征,确定岩石为S型花岗岩,形成于造山后伸展构造环境。     

再论A型花岗岩：对一种残余源模式的评价

0 绪言“A型”花岗岩这一术语是由Loiselle和Wones(1979)引入,用于描述沿大陆裂谷带产生(非造山)而具有弱碱性地球化学特点的花岗岩。一般将它解释为结晶于低水逸度条件下。与其它类型花岗岩相比,A型花岗岩具有高Fe/Mg、(Kq+Na)/Al、K/Na比值和高F、Zr、Nb、Ga及稀土元素(REE)和Y及Zn;具低Mg、Ca、Al、Cr、和Ni值(见Collins等,1982和Whalen等,1987)。因而A型花岗岩富集亲石元素而亏损那些I型、M型和S型花岗岩(解释为源于火成地壳、地幔和沉积源)有亲缘关系的耐熔(refractory)元素。Clemens等(1986)发现A     

个旧花岗岩的微量元素和稀土元素地球化学演化特征

个旧花岗岩，从斑状黑云母二长花岗岩→中粗粒黑云母钾长花岗岩→二云母碱长花岗岩构成了较完整的同源多阶段演化系列，岩浆是以分离结晶方式演化的。不同类型花岗岩的lg(Rb/Sr)-lgSn,lg(Rb/Ba)-lgSn,lgLa-lgSr,lgCe-lgSr,lgEu-lgSr等具有很好的线性关系，REE分布模式的演化也反映了岩浆分异特征。晚期二云母碱长花岗岩是强烈分异的锡多金属矿化花岗岩，其以高Rb／Sr，Rb/Ba比值和低K／Rb、∑Ce/∑Y比值以及Eu强烈亏损为特征。     

赣东南富城杂岩体的地球化学和年代学研究

富城杂岩体出露于赣东南,与闽西南的红山岩体共同构成富城-红山花岗质杂岩。富城杂岩主要由富城黑云母巨斑粗粒二长花岗岩、粗石坝中粒二云母花岗岩和珠长洞含红柱石细粒花岗岩三个单元组成。富城花岗岩含较低的 SiO_2、Rb、Nb 和较高的 Al_2O_3、Ba、Sr、Zr、REE 含量,岩石的 ACNK>1.10,K_2O/Na_2O>1.60。粗石坝花岗岩以高 SiO_2、K_2O,低 CaO、P_2O_5和富 Al(ACNK=1.13～1.20)为特征;岩石含较高的 Rb、Nb 和低的 Ba、Sr、Zr、REE 含量,并具有相对低的 K/Rb 和δ(Eu)比值。珠长洞含红柱石花岗岩的地球化学特征相似于富城花岗岩,除了更高的 ACNK 值(1.22～1.36)和 Rb、Nb 含量以及稍低的 Sr、Ba、Zr、REE 含量。富城单元的~(84)Sr/~(86)Sr 初始比值是0.7135～0.7196,ε_(Nd)(t)是-9.4～-10.2,Nd 模式年龄是1.78Ga 到1.84Ga,其中的锆石 Hf 模式年龄是1.70～1.89Ga,与 Nd 同位素一致;粗石坝单元具有与之相似的 Nd-Hf 同位素组成;珠长洞单元的~(87)Sr/~(86)Sr 初始比值更高(0.7214),ε_(Nd)(t)更低(-16.9),而 Nd 模式年龄达2.37Ga。这些地球化学特征表明富城杂岩体的源岩都是由古老物质组成的沉积岩,其中富城和粗石坝单元起源于具晚古元古代模式年龄的基底,而珠长洞单元的源区物质具有早古元古代平均地壳存留年龄。富城杂岩体的各单元之间没有显示一致的变化规律,表明它们不是单一岩浆演化的结果,它们成分的差异主要受源区成分影响。LA-ICPMS 的锆石 U-Pb 定年显示富城黑云母花岗岩形成较早(239±17Ma),而粗石坝和珠长洞花岗岩形成稍晚(231±16 Ma 和229±6.8 Ma)。它们的形成时代与华南印支期早期构造-岩浆活动的峰期一致。结合地球化学和岩石组合特征,可以认为富城-红山杂岩形成于同构造背景。     

川西洛莫地区燕山早期花岗岩对稀有金属成矿的制约

川西是我国重要的稀有金属产地之一,主要由甲基卡、可尔因、扎乌龙、九龙矿集区组成。甲基卡、可尔因矿集区已发现李家沟、党坝、甲基卡等超大型—大型锂铍矿床,而九龙地区仅发现打枪沟中型锂铍矿床。本文通过对九龙洛莫地区花岗岩开展岩石学、地球化学、锆石及独居石U-Pb年代学研究,以确定桥棚子及其周缘花岗岩的成因、构造背景和伟晶岩的时空联系,为九龙河流域及其周缘的稀有金属找矿勘探工作提供依据。结果显示,桥棚子及其周缘花岗岩具高的SiO₂(69.98%～76.80%)、Al₂O₃(13.72%～15.29%)、K₂O+Na₂O(6.71%～7.24%),为过铝质、钙碱性—高钾钙碱性系列,具低REE、Sr、δEu(0.35～1.02)和HFSE含量,高LREE/HREE、Yb和LILE含量及高分异指数(79.67～91.73),且花岗岩具有较高的Ga/Al比值(10000×Ga/Al=2.45～3.11)。锆石和独居石LA-ICP-MS U-Pb年龄显示,桥棚子岩体成岩年龄为(168.2±0.9...     

松潘造山带金川地区观音桥晚三叠世二云母花岗岩的成因及其地质意义

松潘造山带内发育大量印支期花岗岩,这些花岗岩类对于该地区岩浆活动、基底性质和构造演化的研究有着重要的意义。金川地区观音桥二云母花岗岩位于松潘造山带东部,属于晚三叠世花岗岩。岩石具有高硅(SiO_2=72.08%~73.95%)、富碱(K_2O=4.44%~5.84%、Na_2O=3.29%~3.93%)的特征,其A/CNK值为1.08~1.22,属于过铝质高钾钙碱性S型花岗岩类。岩石富集大离子亲石元素,亏损部分高场强元素,具有明显的Eu负异常(δEu=0.26~0.38)。观音桥二云母花岗岩的ε_(Nd)(t)=-7.9~-10.1(平均为-8.9)不高,Nd同位素二阶段模式年龄T_(2DM)值为1.42~1.57 Ga,显示源岩应该为中元古代地壳岩石。岩石高的Rb/Sr值和低的CaO/Na_2O值、较低的Al_2O_3/TiO_2值和低的Rb/Ba值,表明其起源于泥质源岩的部分熔融。综合地球化学、同位素特征和区域地质资料,笔者等认为金川地区观音桥二云母花岗岩是在松潘造山带挤压背景下,由中—上地壳泥质源岩发生部分熔融而形成。     

湘北华容地区桃花山花岗岩体年代学及地球化学特征

分布于湖南北部华容隆起中的桃花山岩体侵位于中元古代冷家溪群中,由早期细粒少斑状角闪石黑云母花岗闪长岩、细中粒斑状黑云母二长花岗岩、中细粒少斑状二云母二长花岗岩至末期细粒黑(二)云母二长花岗岩等四期侵入体组成.对该岩体中部的中粒斑状黑云母二长花岗岩进行锆石SHRIMP U-Pb测年,获得203Pb/238U加权平均年龄为(140.3±3.8)Ma(2σ)(n=7,MSWD=2.3),代表岩体侵位年龄,表明其成岩时代为晚侏罗世.岩石地球化学特征SiO2＝71.10%～73.00%,K2O＝Na2O=1.09～1.66,属过铝质高钾钙碱性系列;岩石明显富集大离子亲石元素,亏损高场强元素,Rb/Sr＝0.23～1.95;∑REE较高(175.1～259.9),Eu为弱负异常(δ Eu=0.55～0.82),(La/Yb)N=13.52～43.71;低εNd(-8.1～-10.1),高T2DM(1.59～1.75 Ga).综合研究表明,桃花山花岗岩,属壳源含白云母过铝花岗岩类(MPG),为华南前寒武纪基底重熔而成;其形成的构造背景应为碰撞造山作用晚期或结不束时期,陆内碰撞造山作用增温减压体制下的产物,同时也标志着湘北地区在140 Ma后全面转入陆内伸展阶段.     

湘南癞子岭花岗岩体分异演化和成岩成矿

湘南癞子岭花岗岩岩株侵位于燕山早期,其锆石U-Pb年龄为154～155Ma,以富含Li,Rb,Sn,W,Nb,Ta等稀有金属元素,Pb,Zn等贱金属元素以及H2O,F等挥发份为主要特征,具有明显的垂直分带。自下而上,在450～500m的垂直距离范围内,从黑鳞云母花岗岩带,经浅色花岗岩(二云母花岗岩和锂白云母花岗岩)带、钠长石花岗岩带、云英岩带、到块状石英和黄玉伟晶岩带,各带岩石的常量元素和微量元素组成都发生有规律的变化。高度发育的岩浆分异和热液演化,是稀有金属和贱金属元素及挥发份逐步富集并成矿的关键机制。虽然大多数癞子岭花岗岩的样品都具有过铝的特征,但由于该岩体特别是其较深部位的黑鳞云母花岗岩中Zr,REE,Y,Nb,Th,U等高场强元素含量高,锆石的εHf值偏高(在-5.9和-1.9之间,平均-4.2),Hf模式年龄tDM值偏低(在1.32Ga～1.58Ga之间,平均1.47Ga),都显示有地幔物质的明显参与,推测癞子岭花岗岩的原始岩浆,可能来源于深部铝质A型骑田岭花岗岩基,或者是与骑田岭岩基相类似的铝质A型花岗质岩浆体的分离结晶作用。     

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