黔西南水银洞金矿床载金黄铁矿标型特征

水银洞金矿床为近年来在黔西南地区所发现的又一重要卡林型金矿床,黄铁矿为矿床的重要载金矿物。通过系统采样和光片鉴定,区分出具有不同标型特征的四种黄铁矿,即草莓状黄铁矿、生物碎屑状黄铁矿、粗粒自形黄铁矿和细粒自形黄铁矿。四种黄铁矿的含金性存在着显著差异,以生物碎屑状黄铁矿和细粒自形黄铁矿的含金性为优,而草莓状黄铁矿和粗粒自形黄铁矿的含金性较差。各种黄铁矿的主成分及微量组分也显示出一定的变化规律。本文初步分析了四种黄铁矿的形成条件及金的差异性富集机理。     

贵州水银洞金矿床黄铁矿标型特征

通过光学显微镜、SEMI、CP-MS等方法对水银洞金矿床黄铁矿的形貌学、地球化学等标型进行研究,发现黄铁矿具有草莓状、粗粒、细粒、生物碎屑状、胶状等5种类型,且热液型的细粒、生物碎屑状、胶状黄铁矿具有较好的含金性;黄铁矿成矿时矿物成分具有不均匀性,成矿环境动荡变化,导致热液型黄铁矿发育有多层性质各异的环带,进一步证实了黄铁矿具有"三层式"特征;各类型黄铁矿的微量元素具有一定差异。在结合前人研究工作的基础上,通过对黄铁矿的Co/Ni,S/Se和Au/Ag等成分标型数据进行分析,认为成矿热液与深源流体有关。     

藏南查拉普金矿床载金矿物特征与金的赋存状态

黄铁矿和毒砂是卡林型和造山型金矿床重要的载金矿物。文章通过电子探针(EPMA)分析研究了藏南查拉普金矿床不同类型黄铁矿和毒砂中Au、As、S、Fe等元素的含量变化和分布规律,发现不同阶段的黄铁矿具有不同的结构特征和元素组成特点。沉积成岩期黄铁矿(Py1)主要呈草莓状、胶状,常构成环带状黄铁矿的核心,其中金的含量最高,显示了金在沉积成岩期的大量富集。热液期早阶段黄铁矿(Py2)主要呈自形-半自形的立方体,与Py1元素(S、Fe、As)组成相近,显示了一定的继承演化关系。热液期主阶段黄铁矿(Py3)与毒砂共生,多呈自形-半自形的五角十二面体、立方体,常包裹早期的黄铁矿形成环带结构。Py3中As的含量明显升高,其增加量近似等于S的减少量,说明As主要进入黄铁矿晶格替代了S的位置。各个阶段的黄铁矿和毒砂中Au的分布在EPMA微束的分辨率下均显示是不均匀的,Au在Py1和大部分Py2中主要以纳米级自然金(Au0)的形式存在;而在Py3中主要以(Au+)的形式存在,少部分以纳米级自然金(Au0)形式存在。Py1的结构及元素组成与典型卡林型金矿和造山型金矿沉积成岩期黄铁矿的特点相似,而Py3的大量发育则符合卡林型金矿的特征。     

隐伏卡林型金矿区碳酸盐脉地球化学及其对深部矿体的指示作用

贵州水银洞卡林型金矿床位于灰家堡背斜Au-Hg-As-Tl矿田的东段,是该区发现较晚,品位较高(6～18g/t)的大型隐伏卡林型金矿床.矿体全都位于距地表200 m以下,呈似层状、层状赋存于二叠系龙潭组地层所夹的生物碎屑灰岩之中.原生矿石具有去碳酸盐岩化(Decar-bonation)、硅化、硫化物化(Sulfidation)等典型卡林型金矿的热液蚀变特征.     

有机质在卡林型金矿成矿过程中的作用

卡林型金矿,又称微细粒浸染型金矿,是产于沉积建造中浸染状的低温、浅成热液金矿床(Hofstra and Cline,2000)。该类型金矿于20世纪60年代在美国内华达州的卡林镇首次被发现。1978年在贵州黔西南地区册亨县发现了国内的第一个卡林型金矿——板其金矿,随后又相继在黔西南地区发现了丫他、戈塘、紫木凼、烂泥     

贵州贞丰水银洞金矿床成矿规律研究

贞丰水银洞金矿床是通过成矿预测发现的以层控型为主、断裂型为辅的复合型隐伏卡林型金矿床。是滇黔桂“金三角”金矿勘查区层控卡林型金矿的典型代表。在概括水银洞金矿床地质特征的基础上,对矿区内典型金矿点构造蚀变体作了初步的研究与分析,并结合前人研究资料,从成矿物质来源、成矿阶段2个方面对矿床成矿规律进行探讨,初步认为水银洞金矿床的成矿物质来源主要为深部的隐伏岩体;矿床可划分为沉积成岩期和构造-热液期2个成矿期。     

滇东南茶花寨金矿床载金黄铁矿LA-ICPMS原位微量元素组成与地质意义

右江盆地是世界上卡林型金矿床最集中的地区之一,盆地南缘的滇东南地区是其重要组成部分。茶花寨金矿床为滇东南地区产于印支运动不整合面附近的代表性金矿床,黄铁矿为主要的载金矿物,其环带特征明显,为认识该区卡林型金矿成矿作用提供了理想的实例。本文在野外考察及镜下观察的基础上,通过LA-ICPMS分析技术,对茶花寨金矿床中不同期次黄铁矿开展了原位微量元素组成分析,以总结不同成矿阶段金的富集特征与关键控制因素。研究结果表明,该矿床黄铁矿存在3个期次：沉积成因的Py1,包括草莓状黄铁矿Py1a和环带状黄铁矿核部Py1b,交代成因的中间环带Py2,热液成因最外侧环带Py3。其中,Py1b富集Sb、Pb、Zn等元素,Py2富集As、Co、Ni,Py3则具有较高的Au、As、Cu、Sb含量和稍高的Se、Hg、Tl含量。三者对比显示,Py2中As含量最高,Py1b和Py2除As以外的其他微量元素含量接近或Py2中含量稍低,二者Co/Ni比值均在0.1附近,表明Py2为Py1b受热液交代改造形成;而Py3中微量元素组成与Py1b和Py2差异明显,指示其热液成因,且Py3中Co、Ni含量相较Py1b和Py2更低...     

硅化蚀变在黔西南卡林型金矿成矿过程中的作用初探

<正>在热液矿床的成矿作用中,围岩蚀变是极为重要的一环。黔西南地区"卡林型"金矿床以广泛发育较强烈的中、低温热液蚀变作用为特征。而与水银洞金矿床成矿关系密切的热液蚀变有:黄铁矿化、硅化及去碳酸盐化。纵观整个右江盆地或其周缘的"卡林型"金矿床不难发现,以上三种类型的蚀变在成矿过程中占据主导地位,而硅化蚀变,更是与金矿的形成有着密不可分的关系。多数研究者在相关文献中对硅化蚀变进行过描述,不过都仅仅是停留在表面。Cline等(2005)通过对内达华州多个卡林型金矿床的比较后发现     

贵州泥堡卡林型金矿热液蚀变矿物学研究及其地质意义

贵州泥堡卡林型金矿床是黔西南碳酸盐岩台地相区新发现的大型矿床,主要赋矿围岩为上二叠统峨眉山玄武岩组含钙质的玄武质沉火山角砾凝灰岩。因此,泥堡金矿一方面具有一般卡林型金矿的低温矿物组合和载金矿物特点,另一方面由于赋矿围岩的特殊性,还出现一些特征性的热液蚀变矿物。泥堡金矿主要载金矿物为环带状含砷黄铁矿和毒砂,其中黄铁矿可以分为6种类型:草莓状黄铁矿(Py0)为沉积成因,环带状黄铁矿核部的暗色麻点状黄铁矿(PyⅠ)为被热液改造的沉积成因,二者均以低w(As)为特点;环带状黄铁矿的内环(PyⅡ)为热液早期形成的黄铁矿,中间环带(PyⅢ)或者外环(PyⅣ)是热液活动高峰时期形成的含砷黄铁矿,具有典型的高As低S、Fe特点,是主要的含金部位。成矿晚阶段形成的黄铁矿(PyⅤ)与辉锑矿、闪锌矿共生。成矿过程中强烈的水岩交代作用下,峨眉山玄武岩组火山岩中的Ti、P、Cu等元素析出,在矿体中形成较多的锐钛矿、磷灰石、黄铜矿、黝铜矿等特征蚀变矿物。激光拉曼测试表明在低温成矿条件下形成的Ti O2矿物是锐钛矿而不是金红石,因此前人获得的金红石年龄能否代表金的成矿年龄值得商榷。相反,磷灰石、绢云母是主成矿阶段形成的新生热液矿物,其原位测年数据可大致代表金的成矿年龄,因此二者是较为合适的测年对象。成矿晚阶段出现重晶石和石膏等硫酸盐矿物,说明成矿环境更为氧化,同时由于同位素分馏,导致了与硫酸盐共生的硫化物如辉锑矿、雌黄和雄黄的δ34S值相比主成矿阶段的黄铁矿和毒砂更低。热液蚀变矿物学是探讨成矿作用过程的重要基础,在卡林型金矿研究中尤为重要。     

云南者桑金矿床载金矿物标型特征研究

者桑金矿床处在滇黔桂"金三角"构造带中,该矿床的形成经历了沉积成岩期、热液成矿期及表生氧化期,黄铁矿及毒砂为矿床的重要载金矿物。通过岩相学特征、标型矿物研究,发现热液成矿Ⅰ阶段中主要载金矿物为毒砂,热液成矿Ⅱ阶段为金矿化最主要阶段,主要载金矿物为黄铁矿。黄铁矿呈胶状、细粒状、破碎状;毒砂呈粗粒板柱状,维氏硬度偏低为其载金标型。晶胞参数测试表明,黄铁矿a值在5.4300~5.4325之间,成矿Ⅰ阶段至成矿Ⅱ阶段a值逐渐变大。载金毒砂明显富S、Co亏As,导致b、c、β均低于理论值。各成矿阶段的黄铁矿及毒砂中主量、微量元素及硫同位素组成呈现一定变化规律,成矿物质主要来自于富含有机质的围岩。者桑金矿床为中低温热液矿床。     

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.     

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).     

NONMETALS DEPOSITS

正20141520 Bo Ying(Key Laboratory of Metallogeny and Mineral Assessment,MLR,Beijing 100037,China);Liu Chenglin Saline Spring Hydrochemical Characteristics and Indicators for Potassium Exploration in Southwestern and Northern Tarim Basin,Xinjiang(Acta Geoscientica Sinica,ISSN1006-3021,CN11-3474/P,34(5),2013,p.594-602,5 illus.,3 tables,28 refs.)     

MATHEMATICAL GEOLOGY

正20141243Chen Ge(Hangzhou Research Institute of Petroleum Geology,PetroChina,Hangzhou 310023,China);Si Chunsong Study on Sedimentary Numerical Simulation Method of Fan Delta Sand Body(Journal of Geology,     

PROSPECTING EXPLORATION

正20142599Chen Sanming(Guangxi Key Laboratory of Concealed Deposits Exploration,Guilin University of Technology,Guilin541004,China);He Yuzhou Block Model and Reserves Estimation of Panzhihua Iron Deposit Based on 3D Geological Modeling(Journal of Guilin University of Technology,ISSN1674-9057,CN45-1375/N,33(4),2013,p.610-615,9illus.,1table,15refs.)     

STRUCTURAL GEOLOGY

正20140594 Bai Daoyuan(Hunan Institute of Geology Survey,Changsha 410016,China);Zhong Xiang Faults in the Jingzhou Basin and Their Tectonic Settings(Geotectonica et Metallogenia,ISSN1001-1552,CN44-1595/P,37(2),2013,p.173-183,6illus.,59refs.)Key words:basin evolution,tectonic setting,South China In the Upper Paleozoic and Jurassic se-     

STRUCTURAL GEOLOGY

正20141912Cao Hui(State Key Laboratory for Continental Tectonics and Dynamics,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China)Gravitational Collapse and Folding during Orogenesis:A Comparative Study of FIA Trends and Fold Axial Plane Traces(Geology in China,ISSN1000-3657,CN11-1167/P,40(6),2013,p.1818-1828,9illus.,35refs.,with