Principles of Probabilistic Regional Mineral Resource Estimation

Five principal sources of uncertainty in quantitative mineral resource estimation are listed and illustrated by means of a simple example (mosaic model) and a case history study for large copper deposits in the Abitibi area of the Canadian Shield. Abitibi copper potential originally was estimated on the basis of 1968 estimates of production and reserves totalling 3.12 Mt Cu. This prognostication now could be evaluated on the basis of 2008 copper production and reserves totalling 9.50 Mt Cu. An earlier hindsight study performed on the basis of 1977 data (totalling 5.23 Mt Cu) showed seven new discoveries occurring either in the immediate vicinities of known deposits or on broad regional copper anomalies predicted from the 1968 inputs. By 1977, the global geographic distribution pattern of large copper deposits in the Abitibi area had stabilized. During the next 30 years, new copper was essentially found close to existing deposits, much of it deeper down in the Earth's crust. In this paper, uncertainties associated with copper ore tonnage are analyzed by comparison of 2008 data with 1968 data using (a) log-log plots of size versus rank, and (b) lognormal QQ-plots. Straight lines fitted by least squares on these plots show that 1968 slopes provide good estimates of 2008 slopes but 1968 intercepts are much less than 2008 intercepts. In each linear log-weight versus log-rank plot, the slope is related to fractal dimension of a Pareto frequency distribution, and in a lognormal QQ-plot it is determined by logarithmic variance. The difference between 2008 and 1968 intercepts represents the increase in copper ore production and reserves from 1968 to 2008. The Pareto model fits actual copper and massive sulphides increase over the past 40 years better than the lognormal frequency distribution model for 10 km×10 km cells on favorable environments in the Abitibi area.      

Geology and mineralization of the Tiegelongnan supergiant porphyry-epithermal Cu (Au,Ag) deposit (10 Mt) in western Tibet,China: A review

The Tiegelongnan Cu(Au,Ag)deposit in central Tibet contains more than 10 Mt of copper ranking 29 th in the world.It is characterized by typical porphyry-epithermal alteration and mineralization.In order to improve the understanding of porphyry-epithermal copper deposit in Tibet,new zircon U-Pb age and sulfur isotope data along with published data in the Tiegelongnan are presented to investigate the formation and preservation mechanism.Ore-related intrusive rocks in the Tiegelongnan including Early Cretaceous(about 120 Ma)granodiorite porphyry and diorite porphyry are closely related to the northward subduction of Bangongco-Nujiang ocean.Sulfur mainly comes from deep magma,and ore-forming fluid is affected by both magmatic and meteoric water.The metallogenic setting of Tiegelongnan is consistent with those of Andean porphyry copper deposits in South America.The cover of the Meiriqiecuo Formation volcanic rocks,Lhasa-Qiangtang collision and India-Eurasian collision have significance in the preservation and uplift of the deposit.The formation,preservation and discovery of Tiegelongnan play an important role in exploration of ancient porphyry-epithermal deposits in Tibet.     

Carbon cycle variability in tropical Atlantic across two Early Eocene hyperthermals

Early Eocene hyperthermals are geologically short-lived global warming events and represent fundamental perturbations to the global carbon cycle and the Earth’s ecosystem due to massive additions of isotopically light carbon to the ocean-atmosphere system.They serve as ancient analogs for understanding how the oceanic carbonate system and surface-ocean ecosystem would respond to ongoing and future climate change.Here,we present a continuous carbonate record across the Eocene Thermal Maximum 2(ETM2 or H1,ca.54.1 Ma)and H2(ca.54 Ma)events from an expanded section at Ocean Drilling Program Site 1258 in tropical Atlantic.The abundant calcareous nannofossils and moderate carbonate content throughout the studied interval suggest this record was deposited above the calcite compensation depth(CCD),but below the lysocline and under the influence of terrestrial dilution.An Earth system model cGENIE is used to simulate the carbon cycle dynamics across the ETM2 and H2 to offer insights on the mechanism of the rapid warming and subsequent recovery in climate and ecosystem.The model suggests moderate changes in ocean pH(0.1–0.2 unit)for the two scenarios,biogenic methane from a rechargeable methane capacitor and organic matter oxidation from thawing of the permafrost.These pH changes are consistent with a recent independent pH estimate across the ETM2 using boron isotopes.The carbon emission flux during the ETM2 is at least an order of magnitude smaller than that during the Paleocene–Eocene Thermal Maximum(PETM)(0.015–0.05 Pg C yr^-1vs.0.3–1.7 Pg C yr^-1).The comparable pre-and post-event carbonate contents suggest the lysocline did not over deepen following the ETM2 at this tropical Atlantic site,indicating spatial heterogeneity in the carbonate system due to strong dilution influence from terrestrial weathering and riverine discharge at Site 1258.     

Geochronological and geochemical constraints on the petrogenesis of late Mesoproterozoic mafic and granitic rocks in the southwestern Yangtze Block

Late Mesoproterozoic igneous rocks in the SW Yangtze Block are important for understanding the role of it in reconstruction of the Rodinia supercontinent.In the present study,we report new geochronological,geochemical,and Nd-Hf isotopic data for the Cuoke plagioclase amphibolites and granites in the SW Yangtze Block.Geochronological results show that the plagioclase amphibolites and granites have similar late Mesoproterozoic zircon U-Pb ages of 1168-1162 Ma,constituting a bimodal igneous assemblage.The plagioclase amphibolites have high and variable TiO2 contents(1.15-4.30 wt.%)and Mg#(34-66)values,similar to the tholeiitic series.They are characterized by enrichment in LREEs and LILEs,and have OIB-like affinities with positive Nb and Ta anomalies.The plagioclase amphibolites have positive whole-rockεNd(t)(+3.2 to+4.3)and zirconεHf(t)(+4.3 to+10.7)values,indicating that they were derived from an OIB-like asthenospheric mantle source.The granites belong to the reduced peralkaline A-type series and have negativeεNd(t)value of-6.0 andεHf(t)values of-5.8 to-13.8,indicating a derivation from the partial melting of ancient mafic lower crust.In combination with the~1.05-1.02 Ga bimodal igneous assemblage in the SW Yangtze Block,we propose that the Cuoke 1168-1162 Ma igneous rocks were likely formed in a continental rift basin and argue against the existance of Grenvillian Orogen in the SW Yangtze Block during the late Mesoproterozoic.     

Analysis of prospecting polymetallic metallogenic belts by comprehensive geophysical method

This paper is based on the analysis and research on the silver-lead-zinc polymetallic ore in New Ballyhoo Banner in southern Manzhouli of Inner Mongolia.Because metal mineralization brings rock formations,the geophysical features such as low resistivity,high polarization rate and uneven distribution of magnetization,the comprehensive geophysical methods are adopted including high-precision magnetic measurement,high-power induced polarization,IP field middle gradient and controlled source audio-frequency magnetotellurics.In the survey work of multi-metal ore deposits,from surface sweeping to single point measurement,and from single point to section going deeper layer by layer,the resolution of measurement is continuously improved,and various geophysical methods support and complement each other,so explorers can successfully predict the direction,scale and volume of the metallogenic belts in conjunction with geochemical exploration,geological survey and drilling.It has provided a strong basis for completing the exploration task of predicting the reserve volume of ore bodies.The research conclusions of this exploration case have thus a high reference value in the same type of exploration work.     

利用Grapher绘制彩色渐变剖面平面图

在物探扫面工作中,有大量的剖面数据需要绘制成剖面平面图,要求寻找一个高效快速的制图方法.通过对Grapher 自动化功能的分析和实践,编制程序实现了快速绘制彩色渐变剖面平面图的需求,说明利用自动化脚本能够在获得精美图件的同时,可以极大地提高作图效率.     

冷生风化作用对边坡稳定性影响

The experiment shows that considerable influence on density rock properties are subjected by nival weathering conditions. The main parameter defining the rock suitability for solution various engineering and geological problems is its firmness limit on single axis pressing. The firmness properties of sandstone being in absolutely dry condition for Kabakta suite at the beginning of investigation was 64.7 MPa, for Nerungri suite sandstones it was 48. 7 MPa. The investigations showed how much the nival conditions of cryohypergenesis of rock sandstones in Kabakta and Nerungri suites have destructive influence in comparison with aquale and more over aerale conditions. In the aerale conditions sedimentary rock firmness of Kabakta suite decreased to 23.2 MPa, in aquale conditions to 16.5, and in the nivale conditions to 8.9 MPa. In Nerungri suite sandstones are according to 17.7 MPa, 11.1 MPa, and 6 MPa after 300 freezing and thawing cycles. The common sandstone firmness decrease of Kabakta suite was 25 %,of Nerungri suite it was 23.8%. Marlstone samples after 400 FTC decrease to 62% in the nivale conditions and to 33 % in the aerale conditions. After 3～5 years of exploitation marlstone will destruct due to structural and textural inhomogenesis up to gruss, i.e. it will not meet the requirements of durability.Judging by the results of carried out experiment it should be concluded that by cryogenic weathering the sedimentary rocks (sandstones) and rocks with schistose lithogenic texture (marlstone) are subjected to disintegration. The primary rock samples firmness considerably influences on the disintegration rate.     

Cenozoic Sea‐land Transition and its Petroleum Geological Significance in the Northern South China Sea

The process of Cenozoic sea-land changes in the northern South China Sea(SCS)controlled the sedimentary filling pattern and played an important role in the petroleum geological characteristics of the northern marginal sedimentary basins.Under the control of the opening process of the SCS,the northern SCS Cenozoic transgression generally showed the characteristics of early in the east and late in the west,and early in the south and late in the north.The initial transgression occurred in the Eocene in the Taixinan Basin(TXNB)of the eastern SCS,while the transgression occurred until the Pliocene in the Yinggehai Basin(YGHB)of the western SCS.International Ocean Discovery Program(IODP)expeditions(Expeditions 367/368)revealed that the initial transgression of the SCS basin occurred at approximately 34 Ma,which was the initial opening time of the SCS.The period of drastic changes in the sedimentary environment caused by large-scale transgression corresponded to the opening time of the southwestern subbasin(approximately 23 Ma),which also represented the peak of the spreading of the SCS.The sea-land transition process controls the distribution of alternating continent-marine facies,marine facies source rocks and reservoirs in the basins.The marine facies source rocks of the basins in the northern SCS have a trend of gradually becoming younger from east to west,which is consistent with the regional process of gradual transgression from east to west.Regional sea-level changes were comprehensively influenced by SCS opening and global sea-level changes.These processes led to the early development in the east and south and late development in the west and north for the carbonate platform in the SCS.Carbonate platforms form another type of"selfgenerating and self-accumulating"oil-gas reservoir in the northern SCS.The sea-land transition controlled the depositional filling patterns of different basins and laid the foundation of marine deposits for oil and gas resources.The source-reservoircap assemblage in the northern SCS was controlled horizontally by provenance supply and sedimentary environmental changes caused by sea-land transition and vertically by the tectonic evolution of the SCS and regional sea-level changes.     

Geochemical Characterizations of Source and Depositional Environment of Hydrocarbons in the Lake Albert Rift Basin

Despite the upsurge in hydrocarbon exploration in the Lake Albert Rift Basin(LARB)over the past three decades,systematic characterization of hydrocarbon compositions remains lacking,leading to uncertainties in source rock and oil generation determination.We characterized crude oil compositions and oil sand samples in the northern and southern subbasins of LARB.The relative abundance of normal and branched linear alkanes,hopanes,steranes,and aromatic hydrocarbon suggest that northern and southern hydrocarbons were deposited in anoxic to suboxic lacustrine environments and share similar biological source compositions(i.e.,a mixture of plants and aquatic algae and bacteria).Relative to southern samples,northern samples show more negative δ¹³C values for oils,saturates and aromatics,indicating longer migration paths,and exhibit higher MPI-1,DNR-1 and 4-/1-MDBT ratios,indicating higher maturity.Between the two possible sets of source rocks(upper Miocene and Jurassic strata),the positive δ¹³C values of saturated hydrocarbons(average=-20.5‰)suggest that the upper Miocene lacustrine shale is the most likely candidate.Oleanane index(<5% in our samples)does not exclude either source rock possibility,and C₂₈/C₂₉ regular sterane(average=0.63)may be biased by high terrestrial inputs in a lacustrine setting.Together,our data show that northern and southern oils originate from the same source rocks but different oil kitchens.Given the similar geochemical characteristics of southern and northern oils,previous exploration successes in the northern subbasin likely suggest similar potential in the southern sector,while other elements influencing exploration success must be also evaluated.     

《同一个地质计划》的进展与对策

《同一个地质计划（OneGeology）》最初由英国地质调查局于2006年2月提出,已得到全球地学组织的支持。到2007年底,国际地球科学联合会等10个全球学术团体与国际地学组织、2个跨国公司、2位知名人士和67个国家的地质调查局参加了该计划。《同一个地质计划》是各个国家的地质调查局贡献给国际行星地球年的、约1：100万比例尺的、可在网络上很容易取得最好世界地质图数据的计划。该计划的目标是：使可用的地质图数据能被更多的人使用,使需要的人受益,促进互操作能力的增强。《同一个地质计划》的实施,可以提升全球、大陆、行星、海洋地球科学图的编制和出版的合作能力。深化对一些地区地质问题的研究,并可作为国际地球行星年一个切实可用的成果,提升国家地质调查局的形象;运用管理地学知识的领导能力和经验,通过教育、科学、文化和交流。能够处理全球污染对社会、经济和环境的影响问题。促进全球环境保护公约的执行,减缓自然灾害,使全球经济可持续发展,人们的居住环境更安全、更繁荣。精神生活更丰富、更快乐。因此,实施该计划不仅有现实意义,更有重要而深远的政治意义。     

发展我国海底取样技术的几点设想

论述了进行海底取样的意义和目的，介绍了国外研制的各种海底取样器工作原理及应用特点，提出了发展我国海底取样技术的几点设想。     

冲绳海槽中段西陆坡下缘天然气水合物存在的可能性分析

海洋中的天然气水合物主要发育在有机质供应充分、沉积速率快、热流值较高、水深大于300m的大陆斜坡和活动边缘的增生楔发育区;沉积物类型主要以泥质砂岩、砂质泥岩和浊积岩为主。似海底反射层(BSR)和极性反转是识别天然气水合物层的关键标志。冲绳海槽中段西陆坡下缘水深大于1000m;沉积物类型主要为粉砂质泥和泥质粉砂,在部分层位见浊积层。与东海陆架相比,西陆坡下缘的有机质含量、沉积速率的热流值都较高,其范围分别为0.75%～1.25%、10～40cm/ka和70～437mw/m2;单道地震剖面具有明显的似海底反射层(BSR)和极性反转特征,因此,推断冲绳海槽中段西陆坡下缘可能存在天然气水合物层。     

冲绳海槽岩浆活动研究进展及思考

冲绳海槽以其特有的构造地质环境吸引着众多地质学者的关注。针对冲绳海槽地区岩浆作用过程的研究是其中的核心内容之一。本文综述了近年来冲绳海槽岩浆源区物质特征、岩浆形成演化过程及其控制机制等方面研究取得的主要成果,并在此基础上指出了目前冲绳海槽岩浆活动研究工作中存在的科学问题,提出利用铀系不平衡方法研究冲绳海槽岩浆活动的新思路,同时探讨了今后一段时间内的研究方向应该集中在以下四个方面: ①菲律宾板块俯冲的脱水过程对冲绳海槽岩浆活动的作用;②俯冲过程中深海沉积物对冲绳海槽岩浆的贡献;③冲绳海槽岩浆熔融的控制因素;④冲绳海槽火山活动和海底热液活动的成因关系。     

破裂角的确定及其对土压力计算的适用性分析

在使用朗肯或库伦理论设计挡土墙土压力计算时,都涉及到一个非常重要的因素,即土体破裂角的确定,破裂角的确定对挡土墙土压力分析和计算具有十分重要的意义。依据在长期地质灾害治理工程设计中总结的经验,结合常用挡土墙设计中遇到的几种不同情况,以实例剖析解释了破裂角的概念,分析和探论了破裂角的确定及其对挡土墙土压力设计的适用性,提出了在挡土墙设计中,根据不同场景条件确定防护土体破裂角的方法。     

大西洋洋中脊TAG热液区中块状硫化物的Os同位素研究

新测得TAG热液区中5件海底块状硫化物样品的锇含量及其同位素组成,187Os/186Os比值在2.305～7.879之间,均值为5.986,介于现代海水和上部洋壳岩石的锇同位素组成之间,表明该区海底块状硫化物中锇是海水和上部洋壳来源锇混合的产物.在海底热液循环过程中,海水的混入对该区热液流体的Os浓度及其同位素组成产生了明显的影响。     

地形环境对海底热液硫化物矿体内部流体循环的影响

在三层结构热液硫化物矿体模型的基础上, 分别构建了具有不同地形环境的海底热液硫化物矿体模型, 利用数值模拟方法, 模拟了具有倾斜海底面和起伏地形特征的硫化物矿体模型内部温度场和流场分布, 并据此探讨了地形环境在大型海底热液硫化物矿体形成过程中的控制作用.模拟结果表明: (1) 倾斜的洋壳层顶面对于矿体内温度场和流场分布的影响程度有限; (2) 矿体地形起伏是控制矿体内流体运移和热场分布的重要因素; (3) 在热液流体喷出区附近硫化物的堆积速度较快, 易于形成矿体的高地形区; 但随着地形的不断升高, 矿体内部的温度场和流场的分布模式会逐渐发生改变, 导致该区域热液喷口逐渐消亡或者改道.      

智慧地质建设的初步探讨

智慧地质是充分运用新一代信息技术,发现和总结地质演化的时空规律,判断和预测未来发展趋势,集海量专家认知于一体,认识水平可最大程度的符合或逼近地质自然规律,从而使地质成果以智慧的方式服务于人、造福于人。其意义在于以人为本、服务于人,具体内涵表现为实现地质调查监测工作流程的信息化、地质信息资源互联互通的统一化、地质数据分析应用的智能化、地质成果产品服务的精准化。北京市通过不断创新城市地质工作发展理念、搭建由感知到服务的全流程信息化基础,已经基本具备智慧地质的雏形。智慧地质的建设是一个循序渐进的过程,科学谋划、做好顶层设计、夯实地质理论基础、做好信息平台基础搭建是智慧地质当前发展的首要任务。     

Seafloor magnetic lineation off the Otway/West Tasmania Basins: ridge jumps and the subsidence history of the southeast Australian margins

The seafloor off the Otway/West Tasmanian Basins has an east‐west magnetic lineation attributable to seafloor spreading and notionally identified with the set of seafloor spreading anomalies A8‐A20. Anomaly A20 (45 Ma) lies immediately south of a magnetic quiet zone that extends northward past the continent‐ocean boundary (COB). The Southeast Indian Ocean has a constant angular width between the formerly conjugate margins of Australia and Antarctica, consistent with spreading that started along the entire margin about 96 Ma.The proximity of A20 to the Australian COB in some spreading ridge segments is therefore postulated as due to jumps of the spreading ridge to Australia with concomitant transfer of the older oceanic part of the Australian Plate to the Antarctic Plate. Accordingly, the age of the oldest seafloor at the COB in seven original ridge segments is estimated to step from about 96 to 82, 79, and 75 Ma. Break‐up marks a change in the subsidence of the margin from rapid, during rifting by continental extension, to slow during thermal subsidence of the seafloor. Subsequent ridge jumps to the COB are expected to cause uplift or at least still‐stand of the adjacent continental margin. The subsidence history of the Otway/West Tasmanian margin, as indicated by oil exploration wells, is sympathetic with the timing of the postulated ridge jumps in the adjacent seafloor, as is that of the Great Australian Bight Basin with adjacent seafloor to the west, and of the Bass and Gippsland Basins with the Tasman Sea adjacent to the east. The growth of structure at 80 Ma in the outer Gippsland Basin corresponds with a jump to Australia of the Tasman Sea ridge at 82 and 75 Ma, and at 65 Ma in the Great Australian Bight and Otway Basins to a ridge jump to Australia of the adjacent seafloor. The growth of structure at 60 Ma in the Bass Basin and at 55 Ma in the Gippsland Basin corresponds with the abandonment of the Tasman Sea ridge at A24 (55 Ma) during a re‐organization of spreading in the southwest Pacific.     

超低频电磁波遥感探测技术在煤田勘探中的应用

在介绍超低频电磁波探测基本原理、解释方法的基础上,使用由北京大学研制的超低频电磁波地下遥感探测仪,在安徽许疃煤矿、河南平顶山十三矿进行了实际探测,结合文中给出的解释方法对照探测结果对其进行了分析与改进。     

冲绳海槽Jade热液活动区块状硫化物的铅同位素组成及其地质意义

新测行Ｊａｄｅ热液活动区中５件块状硫化物样品的铅同位素组成,具有较小的变化范围,表现出较均一的铅同位素组成特征。在Ｐｂ－Ｐｂ图解上,块状硫化物的铅同位素数据构成线形排列,与该区沉积物和蚀变火山岩的铅同位素组成一致,而与该区新鲜火山岩相比具较高的放射成因铅,证实了该区海底块状硫化物中的铅是由沉积物长英质火山岩来源铅共同构成的混合铅。不同热液活动区铅同位素组成对比研究表明,地质－构造环境的不同是导致各