热液改造成矿机制──四川底苏铅锌矿床成矿作用研究

四川底苏铅锌矿床是一个典型的沉积改造型矿床。改造热液中的铅锌来源于早阶段热水沉积矿石及地层岩石；矿化剂硫源自赋矿地层；介质水属于下渗大气降水。改造热液中的铅锌主要以氯、氟配合物形成迁移。在构造减压带中，铅锌配合物交代地层中的黄铁矿或被有机质还原而沉淀富集。     

银洞子似碧玉岩的海底热液沉积特征研究

陕西柞水银洞子银铅矿含矿层中发育一种似碧玉岩(硅质岩)。岩石同生沉积且速率较快,含钠长石晶屑、重晶石和镁电气石,未见生物作用痕迹。组成元素的分布、变化或关系与现代或古代海底热液沉积物/(岩)一致或相似。稀土配分式样相似于热液沉积硅质岩及现代海水。氧同位素组成与国外热液沉积的硅质岩相近,石英形成温度(80.8℃)高于正常海水温度。地质、岩石学及地球化学提供了较系统的信息证明似碧玉岩的海底热液沉积成因特征。     

广东长坑金银矿床硅质岩中的放射虫化石及生物化石残迹

在广东长坑金银矿床的主要含金岩石碳质硅质岩巾两次找到放射虫化石,其时代可能属于早石炭世。在这些碳质硅质岩中还发现一些生物化石残迹．如石英环、石英圈、石英单晶球、石英多晶球、生物残体和似生物结构。由此认为碳质硅质岩原来含有一定量的微体生物化石．形成于海盆环境,应属沉积成因,这是证明碳质硅质岩属于热水沉积成因而不属于热液蚀变交代成因的有力证据;也表明热水沉积过程有生物物质的加入,热水沉积和生物沉积可以混合发生,说明长坑金银矿床形成手张性、不补偿、水较深的盆地之中。对长坑盒银矿床的矿区含矿地层应泼归属的岩石地层单位提出了疑问。     

粤西长坑金银矿区硅质岩的地质地球化学特征及成因探讨

下石碳统梓门桥组硅质岩是粤西长坑金银矿床的直接容矿岩石。本区硅质岩内层纹状、多孔状、同生角砾状等沉积组构发育，岩石化学成分，微量元素及稀土元素等地球化学特征与加拿大沙利文热液沉积岩等世界著名的热水沉积硅质岩相似，属于热水沉积成因。     

西成铅锌矿化集中区热水沉积成矿作用的岩矿证据

热水沉积成矿与正常沉积矿床在矿质来源和成矿机制上有很大的差异 ,反映在岩矿石结构构造上也有明显的差异性。虽然都有特征的沉积韵律条带、纹层构造 ,但由于热水沉积成矿矿质浓度大而形成了稠密而富集的组构 ,二者可区分。通过对西成铅锌矿化集中区两类热水沉积矿床的岩矿石组构进行论证 ,认为他们不但以上述特征区别于正常沉积矿床 ,而且各自也有差异 ,厂坝式矿床在组构上保留了原始沉积富而大的特点 ,虽有矿物粒度在变质作用中重结晶加粗的富集过程 ,但没有完全破坏原始的热水沉积构造。毕家山式矿床也具有原始沉积特点 ,但在改造过程中有热液叠加交代充填的现象 ,而原始沉积特点则又可区别于热液矿床 ,硅质岩的结构构造就是明显的证据。     

桂西北高龙金矿床含矿硅质岩成因及沉积环境分析

高龙金矿床含矿硅质岩的野外宏观特征、镜下组构特征和稀土元素地球化学特征一致表明硅质岩的形成主要与热水沉积作用有关,而非前人认为的断裂破碎 -热液硅化交代岩。岩石化学、稀土元素和微量元素地球化学特征表明,硅质岩可能形成于大陆边缘 -远洋盆地过渡位置,但更靠近大陆边缘的半深海 -深海环境。     

辽东青城子地区喷流_沉积成矿作用与金银多金属矿化的关系

喷流-热水沉积硅质岩对于矿床研究具有重要意义。通过对青城子地区硅质岩系统的地质学、岩石学、矿物学的研究及对常量元素、微量元素及稀土元素等地球化学数据的分析,认为该地区硅质岩并不是来自陆源碎屑物质,也不是岩浆期后热液蚀变的产物,可能为来自海底喷流-沉积作用所形成的硅质与金、银、铅、锌硫化物一起聚集而成的一种产物,形成于浅海环境。结合区域地质构造演化特征,认为矿床早期存在热水喷流-沉积成岩成矿作用,在矿源岩阶段形成了金、银等金属元素的初步富集。硅质岩的时空分布规律为青城子地区进一步找矿工作开辟了新的思路。     

微细浸染型金矿床的一种新的亚类--硅质岩型金矿

根据广东和广西 3个金矿床 (长坑 ,高龙和果提 )的资料认为 ,微细浸染型金矿 (卡林型金矿 )中存在一种亚类 ,叫做硅质岩型金矿。它以碳质硅质岩为含矿主岩 ,该岩石宏观上呈层状 ,主要由细小的石英和碳质物组成 ,金呈微细浸染状存在。该类矿床具有一般微细浸染型金矿床的主要特征 ,但不属于后生热液蚀变交代成因 ,而是主要通过热水沉积作用形成 ,同时可以混入一定量的生物沉积和冷水沉积的物质。由此认为 ,微细浸染型金矿有多种成因 ,包括后生热液成因 ,热水沉积成因以及其他成因 ,应该从“热水沉积同生成矿”的角度考虑硅质岩型金矿的找矿思路。建议对一些金矿区的“硅化岩”重新研究 ,查明其真正属性。中国南方是寻找硅质岩型金矿床极有远景的区域     

粤中三水盆地长坑金矿赋金硅质岩特征及形成研究

粤中三水盆地长坑赋金硅质岩主要呈层状分布于下石炭统梓门桥组生物碎屑灰岩与上三叠统碳质泥岩（或下石炭统梓门桥组粉砂岩）之间,厚度1—50m,主要由层状、块状及角砾状硅质岩组成。金矿主要呈细脉浸染状产于角砾状硅质岩中。长坑赋金硅质岩层具纹层状构造特征,在其中发现放射虫、微体古生物化石,角砾长轴与硅质纹层平行分布,含有草莓状黄铁矿,这些特征以及长坑金矿床与富湾银矿床成矿时代等资料都表明长坑金矿赋金硅质岩不是简单热水沉积或热液蚀变作用形成的,而是多次硅化作用的产物,至少经历了热水沉积硅化、成岩硅化、金矿成矿热液蚀变硅化及银矿成矿热液蚀变硅化作用的叠加。热水沉积硅质岩形成富金矿源层,为成矿提供了物质基础。     

新疆伊宁县伊尔曼德热泉型金矿床地质特征及成因

伊尔曼德金矿床赋存于下石炭统大哈拉军山组第二岩性段硅化热液喷发角砾岩及其下伏上泥盆统吐呼拉苏组毒砂黄铁矿化凝灰质碎屑岩中,成矿作用可分为热液喷发沉积期和热液交代蚀变成矿期。由热液喷发作用形成的热液喷发角砾岩等热水沉积物,使金发生初步富集,循环的地下水热液与热液喷发角砾岩发生强烈的交代硅化蚀变作用,使金进一步富集而形成矿热泉型金矿床。含矿岩石富含Ａｕ、Ａｇ、Ａｓ、Ｓｂ、Ｈｇ、Ｂｉ,贫Ｃｕ、Ｐｂ、Ｚｎ     

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).     

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.)