金顶超大型铅锌矿床角砾岩及含角砾砂岩分类、特征及成因

兰坪盆地金顶超大型铅锌矿床广泛发育特征特殊的角砾岩和含角砾砂岩,前人对其成因有不同的认识。本文在矿区岩相构造填图的基础上,根据岩石角砾、杂基、胶结物成分和结构特点,划分出以下8类岩石:(1)层状含灰岩角砾砂岩,(2)方解石胶结灰岩砾角砾岩,(3)石膏/硬石膏胶结灰岩砾角砾岩,(4)铁泥质胶结灰岩砾角砾岩,(5)混杂状砂质胶结灰岩砾角砾岩(或称含灰岩角砾砂岩),(6)膏砂泥胶结复成分砾角砾岩,(7)砂质胶结复成分砾角砾岩,(8)含矿石砾角砾岩。其中,含矿石角砾岩形成于矿后,而其它角砾岩形成于矿前且可能近同期形成。角砾岩均处于下部"原地"和上部"外来"地层系统之间。研究认为含矿石砾角砾岩为矿后垮塌成因,其它角砾岩为(含砂)膏盐底辟成因,或含砂膏盐底辟破碎围岩、携带角砾流动的产物。目前角砾岩砂质杂基间的方解石胶结物和灰岩角砾间的方解石胶结物,可能为后期含有机质流体与先存的、作为胶结物的膏盐反应形成。这一过程同时产生H2S,对后期成矿具有重要意义。角砾岩的矿化与膏盐底辟体有关,具"单中心"分带、"多中心"叠加的特点。矿化主要为闪锌矿、方铅矿、黄铁矿等热液矿物交代角砾岩间或砂质杂基间的方解石胶结物,角砾本身弱/无矿化。比较而言,层状含灰岩角砾砂岩为含矿最普遍,次为方解石胶结灰岩砾角砾岩、铁泥质胶结灰岩砾角砾岩、含矿石砾角砾岩,混杂状砂质胶结灰岩砾角砾岩局部含矿。     

西秦岭地区大桥金矿床硅化角砾岩的特征及成因

大桥金矿床是西秦岭地区近年来新发现的一种金矿床类型。矿体赋存在三叠系与石炭系不整合面附近和三叠系内层间滑脱构造中,与硅化角砾岩的关系非常密切,矿化及角砾岩化自不整合面或层间滑脱构造向两侧围岩逐渐减弱。硅化角砾岩体由不同的角砾岩层构成,其产状总体轻微切层,沿走向延伸稳定;角砾主要为遭受不同程度硅化的板岩、灰岩和方解石等,杂基为原地的粉砂屑和断层泥,胶结物为细脉浸染状含金硫化物、微晶石英、玉髓和方解石等。野外观察和岩相学研究表明,大桥金矿区的硅化角砾岩是在早期构造角砾岩遭受强烈硅化的基础上进一步经过多期液压致裂作用形成的,多期次的硅化、液压致裂及自愈合作用导致角砾岩中大量含金硫化物的卸载沉淀。对西秦岭造山带的区域构造分析表明,在与碰撞造山逆冲推覆及随后的板内演化相关的区域变质变形过程中,大规模深部变质热液在压力和热梯度的驱使下沿区域深大断裂上升,多次脉冲式进入地层不整合面及层间滑脱构造中导致岩石发生强烈硅化,进而发生液压致裂作用而形成复杂的含金角砾岩。     

陕西双王钠长石岩特征及金矿床形成期次分析

双王含金钠长石岩带主要为层状 ,产于泥盆系星红铺组粉砂质板岩中。钠长石岩带主要由层状钠长石岩及钠长石岩角砾岩组成。角砾岩角砾主要为层状钠长石岩碎裂形成。层状钠长石岩及钠长石岩角砾韵律纹层构造及条带状构造发育 ,矿物组合和热水沉积钠长石岩相同。钠长石岩主元素及微量元素特征表明钠长石岩具热水沉积的一般特征。角砾岩角砾棱角明显 ,具可拼接破裂构造或典型角砾状构造 ;钠长石岩角砾和早期胶结物矿物组成基本相同。胶结充填物中晶洞构造发育 ,显示同生液压致裂角砾的一般特征。据钠长石岩沉积特征构造及角砾特征 ,认为钠长石岩及金矿床主要是热水沉积 -隐爆作用形成的 ,可分为 4个形成阶段 ,金矿矿化主要和第 3、4阶段有关。     

湖南水口山铅-锌多金属矿田硅化角砾岩体(带)地质特征与成矿关系

水口山铅-锌多金属矿田内的硅化角砾岩体（带）的展布明显地与矿田构造关系密切。根据硅化角砾岩体（带）所处位置的地质环境、构造特征及硅化角砾岩体的产状、成份、胶结物特征的分析,参考镜下鉴定和部分测试资料,将矿田内的硅化角砾岩体（带）分为层间破碎带型、断层破碎型和溢流硅帽泉华型三类,并论述各类硅化角砾岩体与铅锌多金属矿成矿关系的密切程度。     

液压成因含矿构造主要特征——以华南热液钨矿和铀矿为例

液压致裂是整个地壳-岩石圈范围内一种重要的变形破裂方式,也是一些热液矿床的重要含矿构造。通过分析液压致裂构造的形成机制和液压成因含矿构造的类型（液压致裂型和液压撑开型）,以华南地区典型热液钨、铀矿为例,基于野外精细调查,明确了包括石门寺钨矿、行洛坑钨矿和邹家山铀矿等的液压成因含矿构造的基本特征。新生性液压致裂含矿构造的主要特征表现为形态复杂（有弧形、分叉树枝形、放射状、菊花形和蟹腿状等）、规模较小、宏观力学性质以张性破裂为主、走向和倾向多变、方向性不明显、仅局部区域发育优势方位、常伴生有热液隐爆角砾岩;因此,可以从弧形分叉或不规则形态、总体较小规模、产状多向性、分布不均匀性和伴生热液隐爆角砾岩这5个标志来识别液压致裂含矿构造。对比分析液压致裂含矿构造与应力致裂含矿构造的差异认为,液压致裂含矿构造发育比较局限,而液压撑开型含矿构造相对普遍,热液蚀变分带与该含矿构造是液压致裂还是应力致裂无明显相关性;压性成因构造在成矿期表现出的张性力学性质有些是成矿流体超压作用的结果,而并非区域构造应力场的改变;液压致裂导致的断裂末端的扩展破裂与成矿流体的耦合作用为成矿末端效应的构造控制机制。     

山东七宝山角砾岩筒成矿流体构造动力学过程

山东七宝山角砾岩筒内外流体构造（岩）类型多样,具自身特有的时空结构。岩筒内角砾岩胶结胶体中的结晶矿物和矿体类型在空间分布上具规律性的结构特征,并与角砾岩体分布的结构相吻合。角砾岩筒结构,构造的构造动力学分析结果表明,角砾岩筒岩石的破裂形成于流体的双重致裂作用的脉动扩展,即：在流体的热应力和液压双重作用下形成性质不同的节理裂隙和上凸锥面状裂隙带,并脉动式往上扩展形成圆柱状压裂角砾岩体;锥面状裂隙带顶     

湘西合仁坪金矿床角砾岩的地质特征及形成机制

湘西合仁坪钠长石-石英脉型金矿中,角砾岩普遍发育,主要分布于矿脉中,与金成矿关系密切。在详细的野外观察和室内研究的基础上,文章对合仁坪金矿床中角砾岩的形态、大小及胶结物进行了较系统的研究,并结合角砾岩的矿物组合特征,探讨了该区角砾岩的形成机制。研究表明,合仁坪金矿床中的角砾岩大多数呈原地破裂特征,角砾分选差,成分简单,且角砾之间的拼合性较好,为钠长石、石英等热液矿物所胶结,角砾的长轴方向大致具有定向排列的特点,表现出明显的液压致裂特征,反映出成矿流体的特征。研究区的液压致裂作用具有脉动性,每期液压致裂作用大致可分为应力腐蚀、岩石破碎、裂隙愈合3个阶段。     

铜陵凤凰山铜矿床角砾岩的形成与矿床定位机制

角砾岩不仅记录了矿区构造的形成演化过程,同时也记录了矿床的形成定位过程,因此对角砾岩的产出、分布特征研究有利于进一步揭示矿床的形成与定位机制.凤凰山铜矿区不同类型角砾岩的分形研究结果表明,该区角砾状花岗闪长岩属于化学成因角砾岩,在形成过程中有物理作用的参与,而角砾状矿石和角砾状大理岩是水力致裂角砾岩,形成时能量达到中等,说明该区角砾岩的形成与成矿热液的演化密切相关.     

320矿床成因和找矿方向

320矿床的含矿土岩是一套强烈硅化(角)砾状和(角)砾质岩,是地洼初动期岩溶洞穴沉(堆)积岩——以钙屑岩为主的混杂陆源沉积岩,受硅化形成。硅化主要发育于岩溶沉积岩中,并波及它附近的地层。这一事件发生于地洼余动期初,形成于低温环境,硅来自沉积岩源,流体起源于大气降水。320矿床是一个硅化改造的古岩溶矿床,它与美国亚利桑那州的硅化溶解-塌陷角砾岩筒相同。这类矿床在华南碳酸盐岩地区找矿潜力很大。     

金顶超大型铅锌矿床角砾岩分形研究及地质意义

前人研究提出金顶超大型铅锌矿床发育出了多种角砾岩,其成因与盐底辟作用有关。文章对这些角砾岩进行了分形分析,确定了不同角砾岩的角砾形态分维值D_r和粒径大小分维值D_s,来进一步探讨角砾岩的形成过程。其中,D_r表征形态复杂性,可指示角砾迁移距离长短或后化学作用改造情况,D_s表征角砾破碎情况,指示形成角砾的能量大小。研究表明,金顶矿床中一部分角砾岩为蒸发盐或膏砂近原位底辟、破碎灰岩围岩形成,它们具有较小的D_r和D_s值。与这些角砾岩空间过渡的层状砂质胶结灰岩砾角砾岩(或称层状含灰岩角砾砂岩),为蒸发盐而非水流体携带灰岩角砾流出地表,并进入含水沉积系统后形成,角砾未经历水流体搬运、磨圆,具有较小的D_r和较大的D_s值。另外一部分角砾岩为蒸发盐和砂泥质底辟破碎围岩,并共同迁移了一定距离而形成,但总体未发生长距离的迁移,随后进入地表沉积系统中。上述部分角砾岩还经历了形成后的流体交代溶蚀作用,导致D_r值变大。本研究显示,在盐底辟有关铅锌矿床内,赋矿围岩包含多种由不同底辟过程形成的角砾岩。     

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