从成矿和变形时代的不耦合现象探讨康古尔金矿的成因

位于塔里木盆地北缘的康古尔金矿出露于秋格明塔什-黄山巨型韧性剪切带中部,长期以来被当作剪切带型金矿加以研究.通过初步的同位素年代学研究却发现了成矿和变形时代的不耦合现象:康古尔金矿成矿时代在290 Ma左右,而秋格明塔什-黄山韧性剪切带剪切变形时代在225~236 Ma.如果认定康古尔金矿成矿作用发生在海西期,则发生于印支中-晚期的韧性剪切变形作用不仅不是康古尔金矿成矿作用的主因,而且对金矿的改造作用也是有限的.因此,康古尔金矿不能被称为剪切带型金矿.     

Metallogeny of the Baiyangping Lead‐Zinc Polymetallic Ore Concentration Area,Northern Lanping Basin of Yunnan Province,China

The Lanping Basin in the Nujiang‐Lancangjiang‐Jinshajiang (the Sanjiang) area of northeastern margin of the Tibetan Plateau is an important part of eastern Tethyan metallogenic domain. This basin hosts a number of large unique sediment‐hosted Pb‐Zn polymetallic deposits or ore districts, such as the Baiyangping ore concentration area which is one of the representative ore district. The Baiyangping ore concentration area can be divided into the east and west ore belts, which were formed in a folded tectogene of the India‐Asia continental collisional setting and was controlled by a large reverse fault. Field observations reveal that the Mesozoic and Cenozoic sedimentary strata were outcropped in the mining area, and that the orebodies are obviously controlled by faults and hosted in sandstone and carbonate rocks. However, the ore‐forming elements in the east ore belt are mainly Pb‐Zn‐Sr‐Ag, while Pb‐Zn‐Ag‐Cu‐Co elements are dominant in the west ore belt. Comparative analysis of the C‐O‐Sr‐S‐Pb isotopic compositions suggest that both ore belts had a homogeneous carbon source, and the carbon in hydrothermal calcite is derived from the dissolution of carbonate rock strata; the ore‐forming fluids were originated from formation water and precipitate water, which belonged to basin brine fluid system; sulfur was from organic thermal chemical sulfate reduction and biological sulfate reduction; the metal mineralization material was from sedimentary strata and basement, but the difference of the material source of the basement and the strata and the superimposed mineralization of the west ore belt resulted in the difference of metallogenic elements between the eastern and western metallogenic belts. The Pb‐Zn mineralization age of both ore belts was contemporary and formed in the same metallogenetic event. Both thrust formed at the same time and occurred at the Early Oligocene, which is consistent with the age constrained by field geological relationship.     

胶东昆嵛山花岗岩的特征、成因及其与金矿的关系

昆嵛山花岗岩是牟平—乳山金矿成矿带的围岩，在其成因和定位时代上长期存在争议。本文对岩体地质和地球化学特征进行了系统研究，并就岩体成因及其与金矿的关系进行了讨论。作者认为，昆嵛山花岗岩是在中生代由岩浆缓慢冷凝结晶形成的大型复式岩基，并非交代成因。它由垛崮顶片麻状花岗闪长岩（１４７Ｍａ）、八门邹家斑状花岗闪长岩（１３５Ｍａ）、瓦善—水道弱片麻状二长花岗岩及五爪山片麻状含榴二长花岗岩（１２０Ｍａ）组成，成分具贫铝富碱的特点。岩浆来源于中下地壳中酸性变质火山岩系部分熔融形成的岩浆，其形成温度为６５０—７５０℃。岩体经历了韧性和脆性变形作用，不同方向的片麻状构造是岩浆结晶期韧性变形作用的结果。脆性变形形成的断裂和破碎带是本区主要的导矿和容矿构造。花岗岩定位、韧和脆性变形作用与金矿成矿作用有十分密切的关系     

铁镍离子组合对褐煤发酵产甲烷的影响

为研究外源最佳铁镍离子组合对煤发酵产气过程的影响机理,以陕北大柳塔褐煤为例,对不同含量的铁镍离子分别进行煤发酵实验,优选出单一离子的最佳含量,进一步通过二元二次旋转组合设计法确定铁镍离子的最优组合,利用气相色谱、X射线衍射仪、傅里叶红外线光谱分析仪等手段对添加最优组合质量浓度的实验组和空白组（不添加两种离子）产气过程的发酵液及反应前后的煤样进行对比分析。结果表明：Fe²⁺、Ni²⁺的最佳质量浓度分别为15 mg/L、0.005 mg/L,Ni²⁺的添加存在明显的低促高抑现象;添加最优Fe²⁺和Ni²⁺组合的产气量相较于添加单一Fe²⁺、Ni²⁺分别增加了13.64%和20.69%;实验组的pH值、挥发性脂肪酸含量VFA及OD₆₀₀相较于空白组的变化均提前3 d达到峰值,且煤的大分子结构得到更加充分的降解。最后分析了铁镍离子组合对产甲烷过程的影响,阐明了两种微量元素对于促进煤发酵产甲烷的内在机理,研究成果为提高次生生物成因气的产量及产气效率打下了理论基础。     

电气石的偏振拉曼光谱研究

电气石达到宝石级称碧玺。通过电气石偏振拉曼光谱的实验研究,表明随电气石含铁量增高电气石中Ｓｉ－Ｏ伸缩振动峰发生分裂,峰形变大。不同成因的电气石晶体中（ＯＨ）－离子占位不同,变质岩型、矽卡岩型电气石中（ＯＨ）－只有一个有序占位,而伟晶岩型和热液型矿床中电气石（ＯＨ）－离子则有两个无序占位     

安徽池州地区下蜀组沉积环境及成因探讨

采用磁化率、黏土矿物测试及粒度分析等手段,结合区域第四纪地质特征,从气候演变和岩相古地理等角度探讨了安徽池州地区下蜀组的沉积环境及成因.该区下蜀组磁化率曲线呈波峰、波谷旋回特征;黏土矿物以伊利石为主,个别层位以蒙脱石、高岭石、绿泥石为主;粒度以粉砂为主,个别层位以粉砂及中粗砂为主.下蜀组沉积期间存在多次寒冷干燥到温暖潮湿的气候转换,整体为寒冷干燥气候的风成沉积,受古地理位置影响,沿江局部地区夹温暖潮湿气候条件下的长江水系冲积沉积.     

新疆北山小常山铁矿矿物电子探针分析及矿床成因探讨

小常山铁矿位于新疆北山裂谷带西段,矿体赋存于辉长岩、辉长岩和大理岩接触带中,部分赋存于花岗闪长岩和大理岩接触带。前人研究辉长岩年龄为276±1.2Ma,与坡北铜镍硫化物岩浆矿床形成年龄一致,同属早二叠世。小常山铁矿中可见有明显的岩浆贯入现象。矿体主要呈透镜状、块状、脉状、薄层状。金属矿物主要为磁铁矿,含极少量的褐铁矿和黄铁矿;近矿围岩蚀变较弱,主要有石榴子石化、绿帘石化、大理岩化。电子探针研究表明,磁铁矿FeOT含量范围较大,主要分布在85%范围以上,Al_2O_3含量相对较高,TiO_2-Al_2O_3-(MgO+MnO)图解、TiO_2-Al_2O_3-MgO图解均显示热液接触交代成因特点,表明小常山铁矿的形成和岩浆热液的交代作用有关。石榴子石属于钙铝榴石-钙铁榴石系列,与典型矽卡岩矿床的石榴子石端员组分组成有一定差别。结合小常山铁矿体地质特征以及电子探针分析测试等研究,认为小常山铁矿是多成因的复合型矿床,具有岩浆成因和热液成因特征,但后者是主要成因。     

中国煤型气区的构造环境、典型气藏及勘探方向Ⅰ——上古生界煤型气

主要论述以上古生界为烃源岩的典型煤型气藏的地球化学特征、形成时的构造环境与气藏类型及找气前景。华北聚煤区为最有利地区,并总结出煤型气藏形成的２种构造环境和４种成藏类型：裂谷活动构造环境中的古潜山自生自储型（苏桥型）、古生新储型（文留型）和克拉通稳定构造环境中的复合型（鄂尔多斯型）及自生自储型。前述４种气藏类型应为今后该区煤型气勘探的主要类型。此外,还对上述两种构造环境中的煤层气问题进行了扼要讨论。     

国内外前寒武纪条带状铁建造研究现状

条带状铁建造(BIFs)主要发育于早前寒武纪时期(3.8~1.8Ga),记录了早期地球演化的重要信息且蕴含丰富的铁矿石资源。本文梳理总结了国内外BIF相关领域的研究认识及存在问题:1统计对比显示,BIF沉积事件与地幔柱、地壳增生等重大地质事件相关;2稀土元素及Nd同位素示踪表明,Fe来源于海水与海底高温热液的混合溶液,其中高温热液与海水比例为1:1000;3 BIFs缺乏负Ce异常且富集重Fe同位素,暗示沉积时古海洋整体处于缺氧环境以避免Fe~(2+)发生氧化;4一些重要科学问题尚未解决,例如Si的主要来源、沉淀机制及条带成因等;5华北克拉通BIFs多形成于约2.54Ga,BIF类型、形成时代与富矿成因等问题有待深入研究。本文认为,加强国内外典型BIFs的对比研究并适当应用现代先进测试技术,有利于探索BIF沉积的精细过程及古老克拉通的早期演化。     

Concentration–discharge relationships in the coal mined region of the New River basin and Indian Fork sub‐basin,Tennessee, USA

For many basins, identifying changes to water quality over time and understanding current hydrologic processes are hindered by fragmented and discontinuous water‐quality and hydrology data. In the coal mined region of the New River basin and Indian Fork sub‐basin, muted and pronounced changes, respectively, to concentration–discharge (C–Q) relationships were identified using linear regression on log‐transformed historical (1970s–1980s) and recent (2000s) water‐quality and streamflow data. Changes to C–Q relationships were related to coal mining histories and shifts in land use. Hysteresis plots of individual storms from 2007 (New River) and the fall of 2009 (Indian Fork) were used to understand current hydrologic processes in the basins. In the New River, storm magnitude was found to be closely related to the reversal of loop rotation in hysteresis plots; a peak‐flow threshold of 25 cubic meters per second (m³/s) segregates hysteresis patterns into clockwise and counterclockwise rotational groups. Small storms with peak flow less than 25 m³/s often resulted in dilution of constituent concentrations in headwater tributaries like Indian Fork and concentration of constituents downstream in the mainstem of the New River. Conceptual two or three component mixing models for the basins were used to infer the influence of water derived from spoil material on water quality. Copyright © 2012 John Wiley & Sons, Ltd.