460矿床关键控矿要素重磁异常特征及深部结构研究

通过在460矿床开展重、磁勘探工作,研究了控矿要素的重、磁异常特征,分析了主要断裂构造、火山机构、主要岩体的分布情况;利用重磁联合二维正反演、密度界面反演推断了研究区基底界面深度;利用地表地质条件作为约束三维密度反演推断了研究区3大地层的空间分布。研究表明,重磁勘探在火山岩地区确定盆地范围、识别断裂构造效果明显,矿床位置一般位于重磁高场向低场的过渡区域,重磁梯度带是寻找铀矿的重要标志。     

江西相山打鼓顶期流纹英安岩火山通道研究

江西省相山火山盆地是世界第三大火山岩型铀矿区,并且深部伴有Pb-Zn-Ag矿化。该矿区赋矿围岩主要是早白垩世流纹英安岩、碎斑熔岩、花岗斑岩及变质岩。随着对该地区研究的深入,矿田地质勘查取得了令人瞩目的进展,一批新矿床与矿化点在疑似火山颈的深部被发现,然而目前对相山火山盆地古火山通道的研究几乎是一片空白,如:打鼓顶期与鹅湖岭期火山通道是否有继承关系?通过测量及分析相山火山盆地流纹英安岩岩石磁化率各向异性的相关数据,结合野外流面及线理产状,试图探讨这个问题,并初步得到如下认识:(1)铁磁性矿物是流纹英安岩磁化率的主要载体;(2)虽然相山火山盆地后期脆性断裂活动发育,然而从野外岩石露头来看流纹英安岩并没有发生强变形,且磁化率各向异性度P_j小于1.1,指示脆性破裂对磁组构数据影响甚小;(3)研究区内流纹英安岩的磁面理总体上表现出较低的倾角,湖溪镇东部的流纹英安岩大多数表现出低角度或者近水平NNW-SSE方向的磁线理,湖溪镇西部的流纹英安岩则表现出NNE-SSW方向的磁线理,结合盆地内部钻孔及MT资料,指示相山火山盆地流纹英安岩火山通道应位于盆地西侧书塘附近,与碎斑熔岩火山通道可能没有直接的继承关系。     

江西相山火山岩型铀矿田邹家山与牛头岭矿区地球物理特征对比研究

江西相山火山盆地是我国火山岩型铀矿的重要产地,其地形复杂,切割强烈,矿藏分布不均,各矿区具有不同的地球物理特征。利用相山地区重力资料,结合磁法、MT数据以及相关地质资料,运用地球物理反演,比较了邹家山与牛头岭矿床,并用钻孔、遥感以及地质资料做了验证。推测相山矿田存在东、西双岩浆活动中心,邹家山与牛头岭之间存在大型断裂带,两边各有次生断裂,两地矿床在成矿地质环境、物质来源以及成矿深度上存在差异。     

相山火山盆地西部铀矿床分布特征

相山铀矿田目前已发现的矿床主要分布于火山盆地西部和北部。笔者通过对盆地西部铀矿床分布特征、断裂构造及火山岩组间界面控矿特点的研究,认为铀矿区域上受断裂构造控制;火山岩组间界面为铀矿富集空间,西部铀矿床主要富集于火山岩组间界面附近。     

相山火山盆地组间界面、基底界面特征及其对铀矿的控制作用

通过对相山铀矿田钻孔资料、地球物理资料的综合研究,笔者编制了相山火山盆地火山岩组间界面、基底界面等高线图,初步查明了组间界面、基底界面形态特征和埋藏深度,认为火山岩组间界面变异部位为上部铀矿的重要赋矿空间（第1成矿空间）;基底界面控制着晚期花岗斑岩,也控制着下部铀矿的空间定位（第2成矿空间）.组间界面（变异部位）、基底界面与断裂构造复合处,为铀矿最有利的赋存部位.     

江西相山铀矿田古火山口探讨

江西相山火山盆地发育我国第一大、世界第三大火山岩型铀矿田,盆地盖层主要为早白垩世流纹英安岩和碎斑熔岩,这两套火山岩亦是研究区内主要的赋矿岩石,与铀多金属矿化有关的垂向蚀变幅度达千米。近年来,相山铀矿田地质勘查取得了令人瞩目的进展,然而对于矿床的成因及产状等方面仍存在争论,部分原因在于,对流纹英安岩和碎斑熔岩的火山机构研究不够深入。通过对相山矿田的遥感地质解译、碎斑熔岩流动构造测量、磁化率各向异性(AMS)及大地电磁测量(MT)等研究,获得火山通道位置。相山火山盆地流动构造不发育,根据火山集块岩、熔岩中出露的变质岩捕掳体及其长轴统计,结合AMS数据,指示鹅湖岭期碎斑熔岩主火山口位于相山顶,河元背、严坑、柏昌和如意亭为4个次级火山口,而书塘地区可能是打鼓顶期流纹英安岩的火山通道所在。这些推测的火山口在遥感影像上得到环形、放射状构造的印证。相山火山盆地19条MT剖面显示:盆地基底变质岩系与上覆火山岩盖层之间呈连续的水平低阻异常带,不整合界面清晰;打鼓顶组火山岩呈似层状产出,主要分布于盆地西部,并在河元背-船坑-杏树下一带识别出近东西走向的厚层流纹英安岩凹槽;鹅湖岭组火山岩总体呈蘑菇状,中心位置(相山主峰)发育自下而上贯通式的低阻异常,推测为鹅湖岭组碎斑熔岩喷发的通道相(火山颈相)。综合研究表明,相山地区打鼓顶期主要火山通道位于相山顶或其西侧书塘地区,可能存在河元背次级岩浆通道;鹅湖岭期火山活动主岩浆通道位于相山顶,次岩浆通道位于河元背、阳家山、严坑和柏昌,岩浆通道具有继承性和发展性。     

相山铀矿田与斯特列利措夫铀矿田特征对比

相山铀矿田和斯特列利措夫铀矿田均产于破火山口中,相山火山盆地的基底为震旦系变质岩,斯特列利措夫盆地的基底为多期活化的片麻状花岗岩。两盆地的破火山口盖层均为陆相火山岩系,相山破火山口火山岩系为酸性和中酸性岩,斯特列利措夫破火山口火山岩系则为酸性和基性火山岩呈互层产出。破火山口内的构造和蚀变作用发育程度存在明显差异,这是两个铀矿田成矿远景不同的主要原因。     

相山深部铅锌多金属矿化S同位素特征及其地质意义

正相山铀矿田位于江西省乐安县的相山火山塌陷盆地之中,处于扬子板块和华南板块两个构造单元的交接部位(余心起等,2006)。该区地质发展历史复杂,构造运动和岩浆活动频繁,晚侏罗世—早白垩世大规模的火山活动,形成了赣杭火山岩带。白垩纪火山活动减弱并向东迁移,发生了高强度、大规模的铀成矿作用(李子颖等,2014),形成了以相山火山盆地铀矿床为代表的数十个铀矿床(邵飞等,2012)。最近深部钻探工程揭示在相山西部地     

相山等火山盆地主体岩石包裹体研究

闽、浙、赣三省境内广泛发育一种特殊的中新生代中酸性火山岩,具熔岩、火山碎屑岩和次火山岩的特征。对该岩石的认识,看法不一,如江西相山主体岩石曾先后被定名为黑云母微花岗斑岩、自碎次花岗斑岩、凝灰熔岩和酸性碎屑熔岩等,1980年北京铀矿地质研究所又定名为碎斑流纹岩,并将赣杭构造带西南端玉华山等其它六个火山盆地的该岩石统一定名为碎斑流纹岩。正确认识这种岩石的岩性特征和成因机制,不仅对火山岩岩石学和区域地质研究具有重要的意义,而且该岩石与铀矿有一定的成生联系,     

相山火山盆地磁性结构分布特征

以相山地区大比例尺重磁测量结果为基础,建立正演计算模型,采用模拟退火算法,反演计算了相山盆地不同深度下的物性结构分布特征,对该盆地地下岩层结构及界面变化趋势进行了半定量和定性分析;盆地深部构造岩浆活动发育,局部地段次火山岩体具向下延深和扩大的趋势;西北面磁性界面变化较复杂,磁性岩体的埋深均小于800 m;东南面磁性界面变化相对较平缓,磁性岩体的埋深均大于800 m;盆地中有多个岩浆通道,后期构造岩浆活动主要发生在盆地西南侧、南侧以及东侧,这可能是导致北西侧铀富集成矿好于这些部位的主要原因,受构造影响,盆地中部及西北部,磁性基底呈块状分布.这对指导相山的攻深找盲工作有重要意义.     

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.)