蚀变矿物及蚀变分带在角砾岩型金矿找矿中的意义

豫西某角砾岩型金矿床,金矿化富集带、金矿体主要赋存于角砾岩体内的上中部。金矿化与热液蚀变有紧密时空关系。蚀变类型主要有硅化-石英化、正长石化、黑云母化以及绿帘石、绿泥石化和方解石化,并有强烈发育的钠长石化和绿钙(钠)闪石化。研究表明,成矿过程可明确划分为先锋蚀变成矿期、主体蚀变成矿期和晚期蚀变成矿期,构成了比较显著     

鹿儿坝金矿床地质特征与找矿标志

鹿儿坝金矿床产于西秦岭中三叠统浊积岩建造的浅变质岩中的ＮＷＷ向断裂破碎带及两侧硅化蚀变带内。矿石的金矿物由自然金和银金矿组成,以粒间金为主,次为裂隙金和包裹金,矿石分为破碎角砾岩型和碎裂岩型。金矿与围岩硅化、黄铁矿化蚀变关系密切,具有消长关系。微量元素显示Ａｕ－Ａｓ－Ｓｂ－Ｈｇ－Ｂｉ低温矿物元素组合。表明鹿儿坝金矿为低温热液型金矿床。同时指出了沉积相、构造破碎带、硅化黄铁矿化蚀变等找矿标志。     

赣北主要内生金矿床的形成条件

赣北地区的金矿床,可分为含金韧性剪切带型、硅化破碎带型、隐爆角砾岩型和微细粒浸染型等4个类型,其原始成矿物质来源于上地幔,通过火山喷发—沉积作用,形成含金沉积建造和含金火山岩建造.钠、钾质两个系列的花岗质岩石都可以形成金矿床.矿化富集主要通过韧、脆性变形和岩浆隐蔽爆破,产生多次破碎,多期蚀变矿化.在中—低温热液阶段,含矿热液体系的HS~-、Cl~-离子减少,还原介质增加的条件下沉淀富集,形成不同类型的金矿床.     

紫金山铜金矿床地质地球化学特征

紫金山铜金矿床具有“上金下铜”的垂直分带特征，近矿围岩存在一套中低温热液蚀变，金矿与强硅化关系密切，铜矿与硅化一明矾石化关系密切，下部伴生金的铜矿床属岩浆期后中低温高硫热液型矿床，上部金矿床属岩浆期后中低温－低温高硫热液－氧化次生富集叠加型矿床。     

四川锦屏山地区金矿床的成矿机理和成因探讨

在对研究区典型金矿床的矿化地质特征、围岩蚀变特征分析的基础上,讨论了四川锦屏山地区金矿床的成矿机理和矿床成因。锦屏山地区金矿床的含矿围岩以浅变质的三叠系粉砂质片岩为主,金矿床围岩中广泛发育碳酸岩化（早期）和硅化（后期）,前者以铁白云石化为特征,后者以黄铁绢英岩化、绿泥石化和石英脉发育为特征。碳酸岩化主要发生在碳酸岩脉与泥质粉砂岩的接触带上的粉砂岩一侧,由碳酸岩脉侵入时的热液交代岩石中的泥质矿物而形成。金矿体的走向与碳酸岩化带的产状基本一致,金主要富集于硅化强烈、黄铁绢英岩化发育地段。碳酸岩化地层中具有较高的含金背景,指示成矿物质金来源于地幔,而矿化主要发生在黄铁绢英岩化和硅化带及石英硫化物脉中。结合矿床的同位素地球化学特征,认为研究区金矿的成矿作用主要是后期热液的改造作用中金元素发生再次富集的结果。金矿的形成经历了碳酸岩脉侵入、地层发生铁白云石化并初步富集形成矿源层（岩）阶段和以硫化物石英脉为代表的热液期的大规模富集成矿两个阶段,矿床的成因类型因属于改造型金矿床。     

鹿儿坝金矿床成质特征与找矿标志

鹿儿坝金矿床产行西秦岭中三叠统浊积岩建造的浅变质岩中的ＮＷＷ向断裂破碎带及两侧硅化蚀变带内,矿石的金矿物由自然金和银金矿组成,以粒间金为主,次为裂隙金和包裹金,矿石分为破碎角砾岩型和碎屑岩型。金矿与围岩硅化,黄铁矿化蚀变关系密切,具有消长关系,微量元素显示Ａｕ－Ａｓ－Ｓｂ－Ｈｇ－Ｂｉ低温矿物元素组合,表明鹿儿坝金矿为 温热液型金矿床,同时指出了沉积相,构造破碎带,硅化黄铁矿化蚀变等找矿标志。     

豫西南蒲塘金矿床地质特征及成因探讨

蒲塘金矿床属爆破角砾岩型，主成矿期温度２３６～３１８℃，主矿体受爆破角砾岩筒控制，含矿围岩蚀变及矿体变化规律明显，黄铁矿及黄铜矿是金的主要载体矿物。矿石中Ａｕ－Ｃｕ含量呈正消长关系，成矿物质主要来源于花岗岩，从花岗岩的侵入到矿床的形成，大体上经过了晚燕山期浅成初始岩浆侵入－爆破，超浅成强烈爆破及热液成矿三个阶段。     

下坂金矿床地质特征及找矿预测

下坂金矿床位于闽中金矿带,是产于侏罗系火山岩展布区,与次火山岩有关的浅成低温热液型金矿床。金矿体主要产于流纹斑岩的边缘条带相及与之毗邻的隐爆角砾岩中。矿石的矿物组成简单,属少硫化物型矿石,黄铁矿为主要载金矿物,与金矿化有关的热液蚀变作用是硅化、绢云母化和黄铁矿化。矿化富集与流纹斑岩的边缘条带相隐爆角砾岩、硅帽及裂隙发育程度关系密切。     

四川金鸡台金矿床地质地球化学研究

金鸡台金矿床产于碳酸盐岩中，受层间构造破碎蚀变带一格控制。金矿床矿物特征元素组合为Ａｕ－Ａｓ－Ｃｕ－Ｓｂ－Ｂｉ－Ｎｉ－Ａｇ，蚀变类型有硅化和绢云母化；通过稀土元素、同位素地球化学的研究，表明矿质主要来自地层，经由地层卤水和大气降水构成的混合水循环富集，沿断裂充填、交代，形成工业金矿床。     

陕西太白双王金矿床地质特征及稳定同位素地球化学研究

提要：陕西双王金矿床位于西秦岭凤太矿集区东部,为一大型含金钠长角砾岩型金矿床。矿床赋存于上泥盆统星红铺组,为一套由钙质粉砂岩、粉砂质绢云板岩和灰岩组成的类复理石沉积建造。金矿体明显受角砾岩体控制,呈断续带状分布,矿石硫化物主要为黄铁矿,主要围岩蚀变类型为钠长石化。矿床稳定同位素地球化学特征研究表明：早阶段和主阶段成矿流体以岩浆热液和建造水的混合热液为主,晚阶段由岩浆热液向大气降水热液演化;碳主要来源于深部,并混有碳酸盐岩地层溶解形成的碳;硫具有地壳硫和岩浆硫混合来源的特征;铅的来源以上地壳为主,并混有少量地幔铅。结合区域地质构造背景,认为双王金矿床成矿作用与始于印支晚期的陆内碰撞造山作用有关,成矿过程经历了隐爆前的热液交代成矿期和隐爆后的热液充填成矿期,其中隐爆后的热液充填交代阶段是金矿床的主要成矿阶段,双王金矿床成因类型为隐爆角砾岩型金矿床。     

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.     

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.)     

GEOCHEMISTRY

正20142002 Wei Hualing(Institute of Geophysical and Geochemical Exploration,Chinese Academy of Geological Sciences,Langfang065000,China);Zhou Guohua Element Content and Mineral Compositions in Different Sizes of Soil in Tongling Area,Anhui Province(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,32(11),2013,p.1861