金沙江中段含锰铁矿化点的发现及其找矿前景

西金乌兰-金沙江缝合带东侧原雄松群为一套变基性火山-碎屑岩系,是否属于前寒武系一直存在争议。野外调研期间发现铁矿化线索,初步认为铁矿化与原雄松群变基性火山作用关系密切,并受到印支期二长花岗岩的改造叠加,具有较大成矿潜力。矿石多呈块状、蜂窝状、角砾状,少数呈气泡状、瘤状、绳状。矿石矿物主要为含锰磁铁矿,少量赤铁矿、褐铁矿、孔雀石及氧化残留黄铁矿。捡块样分析, TFe多在50%以上,属于含锰富铁矿。通过LA-ICP-MS锆石微区原位U-Pb同位素测年,赋矿变玄武岩的岩浆喷发时代为(228.3±2.1)Ma,表明该地段雄松群的时代为中三叠世,成矿时代也为中三叠世。含矿变基性火山岩为具E-MORB地球化学特征的拉斑玄武岩系列,指示成矿构造环境可能为小洋盆。铁矿化点与地面高磁异常基本吻合。在金沙江中段甚至更大的范围内,与中三叠世变基性火山岩系(原划雄松群)配套的高磁异常区,是寻找火山岩型含锰磁铁矿的重要方向,可能伴生铜-多金属矿化。     

山东大张矽卡岩型铁矿床中铁的富集机制 ——来自流体包裹体和氢、氧同位素的证据

大张铁矿是鲁西地区近年来新发现的一个重要的矽卡岩型矿床.矿体主要赋存于石英二长闪长岩与奥陶系马家沟组灰岩接触带及其附近.根据脉体穿插关系和交代蚀变特征,将大张矽卡岩型铁矿床成矿过程划分为矽卡岩阶段、氧化物阶段、硫化物阶段和碳酸盐阶段.通过对透辉石、绿帘石、石英和方解石等透明矿物显微观察发现,大张铁矿中流体包裹体类型主要...     

航磁梯度数据解释新方法在迁安铁矿勘探中的应用

为更加清晰和准确地利用磁梯度数据获得地质体的分布特征,笔者采用解析信号总水平导数法和梯度欧拉反褶积技术组合实现磁梯度数据的解释,解析信号总水平导数的极值可有效地圈定出矿体的分布范围,梯度欧拉反褶积法可有效地避免背景异常的干扰,从而准确地给出磁性体的位置和深度信息。理论模型证明解析信号水平导数法和梯度欧拉反褶积法的组合可准确地获得磁性体的水平范围和深度。应用于河北迁安地区磁梯度数据的解释,圈定出5个呈条带状分布的较大型铁矿藏,埋深在200~450 m。     

Iron porphyrins in the Permian Kupferschiefer of the lower Rhine Basin, N.W. Germany

Immature samples of the Permian Kupferschiefer from the Lower Rhine Basin in N.W. Germany were analysed for tetrapyrrole pigment type and abundance. The sediment, thought to have been deposited in a marine regime with enhanced salinity, was found to contain high concentrations of metalloporphyrins. The porphyrins are complexed to nickel (Ni) and oxovanadium (V=0), but high abundances of iron (Fe) porphyrins were also detected using UV/visible spectroscopy and mass spectrometry. The presence in the latter of series of aetioporphyrins, cycloalkanoporphyrins, di-cycloalkanoporphyrins and benz-cycloalkanoporphyrins was confirmed by accurate mass measurements; HPLC co-injection of deoxophylloerythroetioporphyrin (C₃₂ DPEP) with the demetallated iron porphyrins indicated its presence in the sediment as an iron complex. The study provides the first evidence for the occurrence of Fe porphyrins in geological samples other than coals and lignites, and reports the highest concentrations in sedimentary organic matter to date.     

Adsorption of Pentachlorophenol onto Oxide and Clay Minerals： Surface Reaction Model and Environmental Implications

The adsorption of pentachlorophenol （PCP） onto quartz, kaolinite, illite, montmorillonite and iron oxides has been investigated by batch equilibrium techniques. The pH-dependent isotherms are curves with peak values, the position of which is at about pH = 5-6 depending on the mineral species. Based on distribution of both speciation of surface hydroxyls on minerals and PCP in solution a surface reaction model involving surface complexation and surface electrostatic attraction is presented to fit the pH-dependent isotherms, and both reaction constants are calculated. The results show that on quartz and phyllosilicate minerals the predominant adsorption reaction is surface complexation, meanwhile both of surface electrostatic attraction and surface complexation are involved on the iron oxide minerals. The reaction constants of surface electrostatic adsorption are usually one to three orders in magnitude, larger than that of surface complexation. The concentration-dependent isotherms can be well fitted by Langmnir equation with the correlation coefficient R〉0.93 for kaolinite and iron oxides. The maximum adsorption is found in the order： hematite 〉 lepidocrocite 〉 goethite 〉 kaolinite 〉 quartz 〉 montmorillonite ≈ illite, which can be interpreted by consideration of both reaction mechanism and surface hydroxyl density. The significant adsorption of PCP onto mineral surfaces suggests that clay and iron oxide minerals will play an important role as HIOCs are adsorbed in laterite or latertoid soil, which is widespread in South China.     

沂水县杏山官庄铁矿地质特征

在汞丹山凸起中分布的基性一超基性岩体,其磁铁矿含量高者可构成矿体。利用高精度磁测、钻探等方法开展了沂水县杏山官庄铁矿的普查工作,大致查明了该矿体的规模、形态和产状,认为该矿床具有低品位、工程地质条件简单的特点,综合分析矿床成因属岩浆分异型磁铁矿矿床。     

济宁岩群大量变质碎屑岩和碳质岩的发现及地层划分

在详细研究济宁市颜店铁矿区报告和以往资料的基础上,对济宁颜店铁矿部分钻孔济宁岩群的岩矿心进行了编录和系统取样工作,发现济宁岩群存在大量变碎屑岩和首次在钻孔中辨别出碳质岩,这对济宁岩群地层的研究和铁矿成矿作用的研究都提供了重要最新资料。对于铁矿的成因研究和原岩及沉积环境的恢复都有重大的意义。依据岩石组合特征和含矿性,济宁岩群自下而上可划分为翟村组、颜店组和洪福寺组。     

微生物参与前寒武纪条带状铁建造沉积的研究进展

地球演化早期太古代和早元古代大规模的条带状铁建造(BIF)是目前世界上最重要的铁矿资源。已有的稳定同位素组成、分子化石以及岩石磁学性质等证据支持早期微生物广泛参与了BIF的形成。本文评述了微生物参与BIF形成过程中铁搬运和沉淀及其同位素分馏、生物标志物和岩石磁学证据。深入地研究BIF成矿中的微生物矿化贡献,有助于解释BIF形成机制,反演前寒武纪大气—海洋环境演化,以及理解地球早期生命的过程。     

鄂西宁乡式铁矿分布层位岩相特征与成因探讨

鄂西宁乡式铁矿分布广、规模大,尤以普遍发育赤铁矿鲕粒而独具特色。并且它一般赋存于加里东运动后第一个海浸沉积序列中由碎屑岩向碳酸盐岩过渡的层位,岩相古地理环境有明显的控制作用。本文铁矿层中赤铁矿鲕粒类型之繁多,结构之复杂,安全可与碳酸盐鲕粒相提并论,其成因亦非常相似,均为强烈搅动环境中机械沉积的产物。经波浪和潮汐水流的再次搬运富集。最后定们于中等一弱动荡环境或相地低凹摈滨相上部。     

冰川底部富铁溶液氧化沉淀:塔里木北缘新元古界库鲁克赛铁矿床的成因

新元古代沉积变质铁矿床是继大氧化事件(GOE)后,沉积间断10亿年(~1800 Ma至~750 Ma)之后,再次大规模出现的一种沉积铁建造类型。这类铁建造与新元古代冰碛岩密切伴生,是新元古代雪球地球事件的重要证据。文章选择与新元古代雪球地球事件有关的沉积变质赤铁矿床—库鲁克赛铁矿进行研究,通过锆石U-Pb定年和区域地层对比工作限定其形成时代为新元古代青白口纪末期—南华纪早期。锆石年龄谱值对比和岩相学研究表明,铁矿床中的碎屑物质主要来自于青白口系下部独断山组石英砂岩地层。主、微量元素研究表明,库鲁克赛铁矿形成于相对富氧或者从贫氧向富氧变化的环境,其成矿元素应主要与陆源物质风化有关,可能有少量成矿元素来自于低温海底热液或海水。笔者认为,库鲁克赛铁矿的形成与成冰纪冰水沉积作用有关,来自冰下水体、从冰下通道中流出的富铁缺氧水溶液与富氧的表层海水混合时,成矿元素快速氧化沉淀,胶结冰水中的近源砾石,进而形成了此种富铁砾岩型铁矿。