辽宁弓长岭三星铁矿矿床地质特征及成因

弓长岭三星铁矿产于鞍山群茨沟组变质岩中,处于弓长岭背斜的北翼.区内主要有2层矿体,呈扁豆状,被F1断层切割成南北2个矿段,围岩主要为混合花岗岩.矿体矿石矿物主要为磁铁矿,矿石品级属需选贫矿石.根据区域铁矿资料,其成因类型为沉积变质型“鞍山式”贫铁矿.     

江苏成矿地质环境及区域成矿谱系研究

通过地质背景及重要矿产区域成矿特征分析、成矿地质环境研究,对江苏省（含上海市）共划分Ⅲ级成矿区带5个、Ⅳ级成矿亚带7个。划分出省内8个主要成矿系列并建立了成矿谱系,初步研究总结了全省重要矿产区域成矿规律。     

抽水试验确定矽卡岩型＋斑岩型硫钼矿床水文地质参数

抽水试验确定含水层水文地质参数是野外水文地质工作中最常用的方法之一。针对铁坑矿区这一岩性复杂的矽卡岩型＋斑岩型硫钼矿床,选择单孔稳定流抽水试验方法进行含水层求参。结果表明,此种方法方便快捷,基本能满足矽卡岩型＋斑岩型硫钼矿床详查要求。并且得出矽卡岩型＋斑岩型硫钼矿床潜水含水层的水文地质参数与岩石的RQD存在一定对应关系的结论。     

A simple lumped mass model to describe velocity of granular flows in a large flume

This paper presents a lumped mass model to describe the run-out and velocity of a series of large flume tests,which was carried out to investigate some propagation mechanisms involved in rapid,dry,dense granular flows and energy transformation when the flows encountered obstacles and reoriented their movement directions.Comparisons between predicted and measured results show that the trend of predicted velocities was basically matched with that of measured ones.Careful scrutiny of test videos reveals that subsequent particles with a higher velocity collided with slowed fronts to make them accelerate. However,this simple model cannot reflect collisions between particles because it treated released materials as a rigid block.Thus,the predicted velocity was somewhat lower than the measured velocity in most cases.When the flow changed its direction due to the variation in slope inclination,the model predicted a decrease in velocity.The predicted decrease in velocity was less than the measured one within a reasonable range of 10% or less.For some cases in which a convexity was introduced,the model also predicted the same trend of velocities as measured in the tests.The velocity increased greatly after the materials took a ballistic trajectory from the vertex of the convexity,and reduced dramatically when they finally made contact with the base of the lower slope.The difference between prediced and measured decrease in velocity was estimated to be about 5% due to the landing.Therefore,the simple lumped mass model based on the energy approach could roughly predict the run-out and velocity of granular flows,although it neglected internal deformation,intergranular collision and friction.     

大功率激电中梯在内蒙古黑山头多金属矿勘查中的应用

随着多金属矿产调查由浅部转向深部的发展,大功率激电中梯多金属找矿中得到广泛的应用。通过大功率激电中梯在内蒙古黑山头矿调中的应用,对激电中梯的工作原理、工作方法、野外数据采集和数据分析进行了研究。解译出了8处激电异常,并圈定了隐伏极化异常区的范围,为进一步地质勘探工作提供了地球物理依据。     

Sediment‐Hosted Gold Deposits in Southeast Asia

Sediment‐hosted gold (SHG) deposits are becoming more widely recognized in the Southeast Asian region. They are characterized by very fine‐grained gold, typically occurring in stratabound jasperoid replacement and structurally controlled orebodies in calcareous or carbonaceous sedimentary rocks, which are commonly distal to porphyry copper–gold deposits. Gold mineralization is associated with anomalous As‐Sb‐Hg‐Tl and is normally concentrated in the arsenic‐rich rims of pyrite and arsenopyrite grains (commonly refractory). The examples discussed in this paper are located in Southeast Asian countries, and all occur in island or continental arc terrains. SHG deposits have many features comparable to the Carlin deposits in Nevada; however, they differ in tectonic setting, their shallow level of emplacement, fluid composition, and probable metal source. As such, the Southeast Asian examples described in this compilation may be classified as “Carlin‐like” but not “Carlin‐type.” Furthermore, they appear to represent a subclass of low‐temperature epithermal deposits, with most occurrences showing late‐stage colloform quartz vein events. Indeed, they are better described as sediment‐hosted epithermal gold deposits. Several examples are multimillion ounce deposits, such as Sepon, Laos, with its endowment of more than 4 million ounces of gold. Mesel, Sulawesi, and Bau (Jugan and Tai Parit), Sarawak, also possessed multimillion ounce resources prior to mining. Two centuries of Chinese alluvial and eluvial mining at Buduk in northwest Kalimantan has produced a significant unrecorded amount of gold. Structurally controlled feeder zones frequently contain higher‐grade gold mineralization (e.g. Mesel), and constitute valid exploration targets. More recently discovered deposits, such as those in Myanmar (Gegalaw, Taungzaw, and Katsena) and the Philippines (Hijo and Las Cogon), remain to be thoroughly explored. Most of the deposits (Sepon, Mesel, Abong, Sihayo, Jugan, Tai Parit, Hijo, and Lascogon) can be directly linked spatially and genetically to gold–copper porphyry intrusive centers. It is postulated that localities with no obvious connection to known porphyry deposits (Buduk, Ban Bak, Kyaukpahto, Gegalaw, Taungzaw, and Katsena) may represent district‐scale exploration targets for porphyry copper–gold deposits. In terms of discovery techniques, of the 13 SHG deposits discussed here, several were sites of historical mining (Mesel, Bau, and Kyaukpahto). The majority, however, are virgin deposits discovered in the past 25 years by intuitive area selection followed by systematic regional geochemical exploration programs and routine geological inspections. At the project scale, electrical resistivity techniques, such as controlled‐source audio frequency magnetotellurics (CSAMT) and induced polarization (IP), have proven to be useful for mapping blind jasperoid bodies and associated feeder zones and silicified structures. Traditional field mapping and stream float sampling in tropical regions are also effective exploration tools. Deposits that have significant jasperoid development may have conspicuous positive topographic relief, depending on erosion level.     

基于大数据分析的铜坑锡铟多金属矿床Sn-Zn-Pb矿化规律及其地质意义

广西大厂矿田不但锡、锌、铅、锑等主要金属储量规模巨大,铟、锗、镉等稀散金属的经济价值也非常可观。本文系统收集整理了铜坑矿床资源勘查、开发过程中形成的1642个工程的编录资料,建立了三维空间数据库,对具有空间属性的Sn、Zn、Pb化学实验数据进行了统计分析。分析结果显示,相对92号矿体和细脉带矿体,91号矿体Sn、Zn品位高、富磁黄铁矿、主量金属相关性差,推测该矿体存在富含Sn、Zn的高温成矿流体叠加。岩浆期后热液型矿床随着远离含矿热液源头Zn/Pb值呈降低趋势,喷流沉积矿床随着距离喷口由近及远、沉积矿层由下往上,Zn/Pb值呈逐步增加趋势。铜坑矿床Zn/Pb空间分布规律是喷流沉积、岩浆热液叠加改造特征的复合,表明该矿床可能为喷流沉积-叠加改造复合成因。东岩墙(花岗斑岩脉)东西两侧随距离变远,Zn/Pb值呈近似对称性降低,推测东岩墙是成矿热液运移的通道。     

滇中楚雄盆地老街子铅-银矿床镜铁矿特征及地质意义

滇中老街子铅-银矿床位于楚雄盆地中部,金沙江-哀牢山富碱侵入岩带南段,是与富碱火山-岩浆热液密切相关的典型矿床。近年来,矿床深部(2073m中段)新揭露出铁氧化物,显微镜下呈亮白色、蓝灰色,针状、放射状、板状构造。通过X射线微区衍射及电子探针分析,确认其为镜铁矿,产出方式有两种:①呈密集星点状,平行岩脉具定向排列,充填于灰紫色黑云母正长斑岩脉长石溶蚀孔洞中;②呈斑点状,分布于岩脉东侧肉红色正长斑岩中,沿岩石裂隙矿化增强。岩脉两侧金属矿物组合差异(方铅矿+黄铁矿+铜氧化物→黄铁矿+铜氧化物+镜铁矿)及正长斑岩颜色差异(灰白→肉红色),与岩脉的侵位密切相关,是构造-岩浆(流体)-蚀变耦合作用的结果。与白马苴金(铜)矿床中镜铁矿对比研究,认为老街子矿床深部镜铁矿对金矿化具有找矿指示意义。相对于星点状、斑点状镜铁矿,呈脉状、网脉状及岩脉内镜铁矿的V2O5、Ti O2含量更高,指示老街子矿床2073m以深可能存在更具规模的脉状镜铁矿。镜铁矿出露位置Cu含量显著增高,局部超过工业品位,达2. 05%,并出现Mo异常(最高含量达0. 11%)、Au异常(最高含量达0. 585g/t),呈现出浅部Pb-Ag矿化和深部Cu-Mo-Au矿化的结构特征,指示深部有斑岩型铜、钼、金的找矿潜力。     

西藏班戈县江错铁矿正长斑岩锆石LA-MC-ICP-MS U-Pb定年及意义

在班戈县东偏北约100km的江错铁矿采集正长斑岩样品,进行系统的岩相学、地球化学及锆石LAMC-ICP-MS U-Pb定年。结果显示正长斑岩的SiO_2含量变化为59.55%～62.61%,平均值61.52%,Na_2O含量变化为9.31%～10.01%,平均值9.74%;K_2O含量变化为0.107%～0.12%,平均值0.113%,里特曼指数变化范围为5.16～5.36,属于钠质碱性岩系列,是班公湖-怒江缝合带中段班戈地区首次发现的碱性岩。锆石U-Pb年龄为170±2.4Ma,表明其为中侏罗世的产物。综合对比区域地质资料,认为这套正长斑岩应该是班公湖-怒江洋盆开始俯冲早期的不成熟岛弧阶段的产物。     

Comparison between Datangpo-type manganese ores and modern marine ferromanganese oxyhydroxide precipitates based on rare earth elements

Datangpo-type sedimentary manganese deposits, which are located in northeastern Guizhou province and its adjacent areas, are Mn carbonate-type deposits hosted in black carbonaceous shale that represent a series of medium to large deposits containing a huge tonnage of reserves. PAAS-normalized rare earth element distribution patterns of manganese ores record “hat-shaped” REY (REE + Y) plots characterized by pronounced middle rare earth element enrichment, evident positive Ce anomalies, weak to strong positive Eu anomalies and negligible negative Y anomalies. These REY geochemical characteristics are different from those of country rocks and record the processes and features of sedimentation and diagenesis. Manganese was precipitated as Mn-oxyhydroxide particles in oxidized water columns with the sorption of a certain amount of rare earth elements, subsequently transforming from Mn-oxyhydroxides to rhodochrosite and redistributing REY in reducing alkaline pore-water during early diagenesis. A number of similarities can be observed through a comparison of Datangpo-type manganese ores and modern marine ferromanganese oxyhydroxide precipitates based on their rare earth elements. The precipitation of Datangpo-type manganese ores is similar to that of hydrogenetic crusts and nodules based on their positive Ce anomalies and relatively higher total REY concentrations. However, several differences also exist. Compared to hydrogenetic crusts and nodules, Datangpo-type manganese ores record smaller positive Ce anomalies, lower total REY concentrations, unobvious fractionation between Y and Ho, and weak to strong positive Eu anomalies. These were caused by quicker sedimentary rates in the oxic water columns of the shallower basin, after which pore water became strongly reducing and alkaline due to the degradation of organic matter in the early diagenetic stage. In addition, compared to typical deposits in the world, Datangpo-type manganese ores are similar to hydrogenetic deposits and different than hydrothermal deposits. All of these characteristics of manganese ores indicate that Datangpo-type manganese ores, the principal metallogenic factors of which include oxidation conditions during deposition and reducing conditions during early diagenetic stages, represent hydrogenetic deposits.