山东张家洼矽卡岩型铁矿矿物学特征及其对成矿环境的指示意义

张家洼矽卡岩型铁矿位于华北克拉通东南部,赋存在石炭系本溪组与奥陶系马家沟组之间的假整合面处及闪长岩体与奥陶系马家沟组大理岩的接触带附近,富铁矿石资源量已达大型规模。研究发现矽卡岩矿物种类在内外接触带分布有一定区别,内带为石榴石等钙质矽卡岩矿物,而外带为阳起石、金云母等镁质矽卡岩矿物,整体构成钙镁质矽卡岩。对矽卡岩矿物系统的研究表明,透辉石及石榴石发育有环带,其氧化物含量随矿物环带的形成比例不断变化,暗示酸碱度及氧逸度随着成矿流体的演化而发生相应的变化,即由早期矽卡岩阶段的相对还原的酸性环境演化为退化蚀变阶段相对氧化的碱性环境从而导致铁质逐渐萃取多次富集、沉淀,后期随着磁铁矿的沉淀又逐渐在硫化物阶段转化为还原环境生成金属硫化物。     

鄂东南地区鸡笼山矽卡岩金矿床的矽卡岩矿物学特征及其意义

鸡笼山金矿是长江中下游鄂东南地区典型的矽卡岩金矿床,其矽卡岩矿物学特征研究较少。围岩为三叠纪大冶组灰岩和白云质灰岩,决定了该矿床发育丰富的矽卡岩矿物组合,主要包括石榴石、透辉石、硅灰石、绿帘石、金云母等。本文详细研究了不同阶段矽卡岩的矿物学特征,并对其进行了电子探针分析（EMPA）。结果表明石榴石属于钙铝-钙铁系列,辉石为透辉石,以钙铁榴石-透辉石共生的富金矽卡岩组合是在较高氧逸度和较低酸度条件下形成的,具有铜金矿的成矿专属性。伴随着流体的演化,矽卡岩与矿体在时空和成因上都具有密切的联系。结合矿区内发育有斑岩型矿体,暗示鸡笼山金矿床可能具有统一的斑岩-矽卡岩型成矿系统,深部具有很大的找矿潜力。     

白山市三道阳岔铁矿床磁铁矿工艺矿物学研究

磁铁矿工艺学研究主要为白山磁铁矿在后期详查,开采,选矿方面,提供科学依据,对其进行了工艺学研究,研究结果表明:矿石中可供回收的主要金属矿物为磁铁矿,其他均达不到综合利用指标。     

西北某喷流沉积型铁铜矿工艺矿物学研究

西北某铁铜多金属矿床规模大,具有铁、铜、金、铅锌等多金属矿化,属于海底喷流沉积型矿床。笔者采用工艺矿物学研究方法,查明了矿石工艺矿物学特性。研究结果表明,矿石的组成矿物种类较为复杂,铁矿物主要是磁铁矿、半假象―假象赤铁矿和菱铁矿,其次为赤铁矿,铜矿物主要包括黄铜矿和斑铜矿。矿石中铁矿物和铜矿物均具不均匀细粒―微细粒嵌布特征;通过选矿可获得铜精矿和铁精矿。     

Mineralogy of metal contaminated estuarine sediments,Derwent estuary,Hobart, Australia: implications for metal mobility

The mobility, bioaccessibility and transfer pathways of metals and metalloids in estuarine sediments have been the focus of much detailed research. However, to date, few studies have examined the mineralogical siting of metals and metalloids in such sediments. This is despite the fact the mineralogy of sediments is an important factor that controls which and how much of a particular metal is released to pore waters and overlying water columns. This study reports on the mineralogical siting of metals in contaminated estuarine sediments, Hobart, Australia, and aims to evaluate the mobility of metals in the contaminated substrates. Mineralogical, mineral chemical and bulk chemical analyses demonstrate that the sediments contain very high levels of several metals and metalloids. The contaminated sediments have concentrations of zinc (Zn), lead (Pb), copper (Cu) and cadmium (Cd) ranging from 0.55 to 4.23 wt%, 0.16 to 0.70 wt%, 415 to 951 mg/kg and 23 to 300 mg/kg, respectively. Franklinite and lesser sphalerite are the main repositories of Zn, whereas much of the Pb and Cu is hosted by sulfides, organic matter and undetermined iron (Fe) oxides. While the release of contaminant loads from franklinite through dissolution is likely to be insignificant, even small releases of metals from the highly contaminated sediments can still cause the deterioration of local water quality. The contaminated sediments represent long-term sources of metal pollutants, particularly Zn, to local waters. This study demonstrates that mineralogical analyses are a vital tool to recognise the potential mobility of trace metals in estuarine environments.     

Diagenetic and low-grade metamorphic terranes of Gaspé Peninsula related to the geological structure of the Taconian and Acadian orogenic belts, Quebec Appalachians

Abstract Illite crystallinity (IC) measurements, determination of the proportion of 2M mica-polytypes and organic-matter reflectance measurements establish regional diagenetic/low-grade metamorphic trends for the Taconian and Acadian belts of Gaspé Peninsula. IC varies as a function of many factors besides maximum burial temperature and heating time. Correlation between IC and %2M illite polytypes for the Fortin Group and Temiscouata Formation suggests (i) that the amount of high-grade detrital mica in the samples is low, and (ii) that IC can be used with some confidence as an estimator of regional thermal maturation levels. Correlation of these parameters with available organic reflectance values further supports this assumption. The illites of the Temiscouata and western Fortin groups are mostly phengitic in composition, whereas in the eastern outcrop belt they are more Mg- and Fe-rich (celadonitic), but generally also of lower grade and lower 2M content. The d(060) values for illites measured on the unorientated <2-μm fraction of samples fall between 1.502 and 1.503 Å (range: 1.500–1.504 Å), indicating relatively low octahedral occupancy by Mg and Fe (between one-fifth and one-third of the available spaces). Pyrophyllite and paragonite were not detected. Chlorites are Fe-rich and ripidolitic. The IC map for the Acadian belt of the peninsula displays general congruence between IC contours (2200 sample points) and structural trends for the 27,000-km² area. The highest grades (anchimetamorphic) are associated with the oldest rocks (Honorat and Matapedia groups) exposed in the cores of major anticlines. Anchimetamorphic grades associated with the western outcrop belt of the Lower Devonian Fortin Group require 7–8 km of subsidence to accommodate sufficient thickness of overlying younger rocks (on top of 4–5 km of Fortin Group deep-water clastics) to explain the grades in terms of burial metamorphism assuming a geothermal gradient of 30° C km^?1. The lowest-grade diagenetic rocks occupy a large area in the northeastern part of the peninsula, smaller areas in the northwestern part of the Acadian belt, in the centre of Chaleurs Bay synclinorium, and in the Ordovician Mictaw Group. The contact between the Taconian and Acadian belt is marked by a distinct maturation discontinuity. The Grand Pabos fault juxtaposes rocks of contrasting maturation levels (Matapedia Group against Fortin Group) in the west, but shows no maturation offset further east in the Honorat Group. The fault zone limiting the Fortin Group in the north is also associated with a major IC jump.     

广西金牙金矿床石英的标型特征及其意义

本文通过对金牙金矿床石英的化学成分、包裹体、物理性质及稳定同位素等万面的矿物学特征研究,取得了有价值的成因信息和找矿标志。认为该矿床属浅成中低温地下热(卤)水渗滤型金矿床,成矿物质来源于地层围岩。还指出石英颗粒极细小,多为隐晶至微晶,自形程度低,呈白色或无色、透明;比重低,晶胞棱长a_o大而Co小、单位晶胞体积增大(与标准石英比);红外光谱有1个宽峰、4个吸收峰和2个强的特征峰的波段,具单峰或双峰发热光曲线(在50～350℃范围内);具结构铝,含Ca、Fe、Mn、Au、Ag、Co、Ni、Se、Te与∑REE等杂质元素,其中Au与Al成正相关,而Au与∑REE呈负相关;包裹体呈无色透明、个体细小且少,以液相为主.气液比低,且出现沸腾包体群,其含盐度低,无子矿物,Na、Ca较高,为富含CO_2,CH_4的Ca~(-2)-Na_a-HCO_3~1-Cl型地下热(卤-水(温度305～190℃、压力25669～16945kpa.深度小于1km);δ~(18)O、δ~(18)O_(H_2O)、δD值具大气降水特征,δ~(13)C值类似油田碳等特征,是找“金牙型”金矿的重要找矿标志。     

利用X射线粉晶衍射和电感耦合等离子体质谱法研究江西西华山钨矿床中黑钨矿的矿物学特征及指示意义

目前针对江西大型黑钨矿石英脉型钨矿床西华山的黑钨矿矿物学特征及指示意义研究较少。本文利用X射线粉晶衍射分析和电感耦合等离子体质谱分析技术对黑钨矿晶体结构、化学成分特征及空间变化规律开展研究。获得黑钨矿晶胞参数为a0=0.477 nm,b0=0.573 nm,c0=0.498 nm,β=90°21',属于锰钨铁矿,与前人得出的黑钨矿晶胞参数略有不同,代表不同元素对铁锰的类质同象替代。主要化学成分WO3、Fe O、Mn O的含量在空间上具有一定的变化规律,反映了成矿物质的运移特征。微量元素Sc、Y、Nb、Ta在垂向含量变化大,说明矿液运移具有复杂性。稀土总量ΣREEs较高(397.16×10-6~1071.11×10-6),具有强烈的Eu负异常,具重稀土富集左倾的"躺椅式"球粒陨石标准化配分模式。将西华山、盘古山、淘锡坑、大吉山4个典型矿床的黑钨矿稀土元素特征进行对比,反映产在花岗岩内接触带的黑钨矿的稀土总量(ΣREEs)相对最高,分馏最明显;产在花岗岩内及其外接触带的黑钨矿的稀土总量(ΣREEs)相对较低,分馏程度最不明显;而产在花岗岩外接触带的黑钨矿的稀土总量(ΣREEs)有高有低,分馏程度有强有弱。因此,黑钨矿的化学成分变化特征,可以有效地指示成矿物质空间运移特征、物质来源和矿床成因。