相山铀矿田杏树下地区科学深钻岩心物性特征分析

相山铀矿田为我国主要铀矿资源基地之一,随着多种地球物理工作在该地区的开展,对岩矿石物性的研究,特别是对接近自然赋存状态下的岩石物性的研究就显得极其重要。文章以相山铀矿田杏树下地区科学深钻为研究对象,通过对其岩心密度、磁化率、电阻率、极化率等物性参数进行统计分析,得到了该区主要岩性的上述物性参数值,结果表明,杏树下科学深钻中碎斑流纹岩表现出低密度、高磁化率、高电阻率、中极化率的特点;流纹英安岩表现出中密度、中高磁化率、中低电阻率值、高极化率的特点;凝灰岩则表现出密度范围大、低磁、低电阻率、低极化率的特点;泥岩、粉砂岩是高密度、低磁化率、低阻、低极化率的特点;板岩是高密度、低磁化率、高电阻率、中极化率的特征。上述物性参数结果为后续在该地区开展电磁、磁法及重力勘探提供了物性基础。     

辽宁抚顺地区铁矿地球物理模型——以毛公堡铁矿为例

辽宁抚顺地区铁矿十分丰富.它们与著名的鞍本铁矿同属辽东吉南成矿带.成矿地层均为鞍山群，属沉积变质型铁矿，受变质岩系层状控制明显.鞍山-本溪地区为鞍山群的茨沟岩组、樱桃园岩组；抚顺-清源地区为鞍山群的石棚岩组、通什村组.它们具有相似的岩性组分和物性特征.通过开展“深部盲矿体勘查技术研究”科研项目，以抚顺毛公堡铁矿为例，总结分析抚顺地区铁矿的重磁电物性特征，建立了地球物理模型.研究认为，应当打破传统的以磁测为唯一手段的磁铁矿勘查工作模式，开展重、磁、电联合勘查是可取的、有效的.在水平定位技术方面，重力方法有其独特的优势；在垂向定位技术方面可以开展电(磁)测深工作.磁铁矿的极化作用是明显的，应符合低阻高极化.铁矿重磁电特性是高磁、高密度、高极化、低电阻，呈“三高一低”的物性特征，而且品位越高极化率越高.电阻率应不高于2 000Ωm，极化率应不低于6%，磁化率不低于100 000×10^-6 SI，密度高于3.00×10³ kg/m³.     

川西凹陷钙芒硝矿地球物理特征分析

川西凹陷白垩系灌口组复式沉积多层品位高的钙芒硝矿,为更好地识别钙芒硝矿赋存层位,通过开展视电阻率、自然伽马测井,以及高密度电阻率法勘探,建立起含钙芒硝矿的地球物理特征。含钙芒硝矿电阻率相对于非含矿地层表现为明显的高电阻率,低自然伽马,高密度电阻率剖面表现为明显的高阻特征。因此分析川西凹陷钙芒硝矿地球物理特征,有助于提高对该区钙芒硝矿勘查、采空区调查的认识。     

基于不同装置的高密度电法对低阻填充溶洞探测的对比

高密度电法勘探中,不同条件下的溶洞起反演电阻率特征有差异,溶洞为空洞时反演电阻率表现为高阻,充满低阻物质时表现为低阻,而当低阻物质含量不同时各个装置的探测效果会有不同。为了比较高密度电法不同装置对低阻填充溶洞的探测效果,构建低阻物质含量不同的低阻溶洞,正演计算了不同装置下的视电阻率,利用最小二乘法对模型的地电断面进行反演。     

基于不同装置的高密度电法对低阻填充溶洞探测的对比

高密度电法勘探中,不同条件下的溶洞起反演电阻率特征有差异,溶洞为空洞时反演电阻率表现为高阻,充满低阻物质时表现为低阻,而当低阻物质含量不同时各个装置的探测效果会有不同。为了比较高密度电法不同装置对低阻填充溶洞的探测效果,构建低阻物质含量不同的低阻溶洞,正演计算了不同装置下的视电阻率,利用最小二乘法对模型的地电断面进行反演。     

基于不同装置的高密度电法对低阻填充溶洞探测的对比

高密度电法勘探中,不同条件下的溶洞起反演电阻率特征有差异,溶洞为空洞时反演电阻率表现为高阻,充满低阻物质时表现为低阻,而当低阻物质含量不同时各个装置的探测效果会有不同。为了比较高密度电法不同装置对低阻填充溶洞的探测效果,构建低阻物质含量不同的低阻溶洞,正演计算了不同装置下的视电阻率,利用最小二乘法对模型的地电断面进行反演。     

基于cole-cole复电阻率模型的线源可控源有限元数值模拟

受激发极化效应的影响,大地中岩(矿)石电阻率是一个与频率、电化学性质等因素有关的复电阻率。接收到的电磁场信号中,包含了电磁感应效应以及激发极化效应双重因素的影响。将cole-cole复电阻率模型引入二维线源可控源正演理论,加载伪delta函数,实现了含激发极化效应的线源可控源有限元数值模拟。计算了不同极化参数的二维地质体线源可控源的影响特征。结果表明:线源可控源响应对IP效应反映明显,视电阻率出现增高的特征;低阻高极化相对于高阻高极化模型受IP效应影响更大,从低阻中提取IP效应更加乐观。该研究为实现从复杂地质条件下CSAMT信号提取IP效应奠定了基础。     

四川攀枝花晶质石墨矿电性特征及找矿评价

[研究目的]石墨具有高的电子导电性,电性呈现形式为低阻(<10-5Ω·m)高极化(>40％)特征,正是由于石墨的超低阻特性,在石墨矿地球物理勘查中经常遇到"低阻屏蔽"作用,因此,优选有效的电法勘探组合在石墨矿勘查中非常重要.[研究方法]本文选择四川攀枝花中坝晶质石墨矿开展正演模拟,同时对典型矿床开展自然电位法和宽频电磁...     

大兴安岭南段锡多金属矿找矿勘查综合模型

维拉斯托矿田是大兴安岭南段一个典型的热液脉型锡多金属矿田。成矿地质特征显示，深部隐伏碱长花岗岩为其成矿地质体，两者之间存在显著的空间依存关系，呈现明显的矿化蚀变分带，成矿中心钨锡- 锂铷矿化，多伴生有云英岩化、硅化，两侧均有铜铅锌银(萤石)矿化，常出现较强的褐铁矿化和萤石化，构成一套较完整的岩浆- 热液锡多金属成矿系统。地球化学特征显示，其分带清晰，W、Sn、Mo、Bi位于异常中心部位，Cu、Zn、Pb、Ag、As、Sb等元素位于异常外侧。自然重砂特征显示，重砂矿物也呈现较为明显的分带，矿田中心以锡石重砂颗粒相对较多，矿物组合为锡石+闪锌矿+黄铁矿，外侧硫化物矿化区锡石变少，重砂矿物组合为黄铜矿+闪锌矿+方铅矿+黄铁矿。地球物理特征表现为，成矿中心的锡钨多金属矿对应物探测量的低重力、中低极化率、中高阻率与低磁特征，局部出现略高激电异常。边部的铅锌银多金属矿所对应物探测量的高重力、高极化率、低电阻率和高磁特征。综合分析维拉斯托矿田地物化等方面信息，建立了锡多金属矿床的找矿勘查综合模型。     

榆林地区浅埋煤层采空区电法综合勘探技术

为探明榆林地区浅埋煤层不明采空区,分析了其浅埋煤岩层垂向、横向正常电性特征以及存在采空区时的异常电性差异特征,从而确定榆林地区具备使用瞬变电磁法和高密度电法探测采空区的电性基础。然后开展了瞬变电磁法和高密度电阻率法探测的施工参数试验,建立相应的施工技术体系,实现了榆林地区浅埋煤层采空区的有效综合勘探。结果表明:(1)榆林地区正常地层垂向电性呈稳定的"低阻-高阻-低阻"趋势特征,而当煤层中存在地质异常体时,横向差异明显,出现不连续的高阻或低阻特征;(2)瞬变电磁法采用240 m×240 m发射线框、14 A发射电流、25 Hz发射频率、2048次叠加次数,高密度电阻率法采用20 m接收极距,这些施工参数可以满足榆林地区浅埋煤层采空区的电磁法探测要求;(3)瞬变电磁法、高密度电阻率法探测的异常区范围基本一致,在两种方法重合异常区打钻揭露采空区,说明两种方法可互相补充、验证,为应用于榆林地区煤层采空区综合物探的合理手段。     

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