新疆西天山智博铁矿岩浆-热液成矿作用—来自安山岩矿物学的证据

本文以智博铁矿区内的安山岩为研究对象,通过详细的野外地质调查,并利用电子显微镜和电子探针,对安山岩中的主要矿物进行了系统的岩相学观察和矿物学研究。研究表明,智博安山岩中斜长石主要为Na-高钠长石,具低TiO2,高Na2O和Al2O3的特点;辉石主要为普通辉石,具高TiO2,高Al2O3的特点;角闪石主要为镁角闪石和阳起石,具低TiO2和Al2O3,高MgO的特点;副矿物磁铁矿具高TiO2,低MgO和Al2O3的特点。辉石、角闪石矿物化学特征表明,智博铁矿安山岩的母岩浆属于壳幔混源的玄武质岩浆,构造环境为火山岛弧环境。智博安山岩中单斜辉石结晶温度为1225℃左右,结晶压力约0.795GPa,结晶深度约26km。智博铁矿后期的热液作用也参与了磁铁矿成矿,对智博铁矿的成矿有一定的贡献。     

西天山铁木里克铁矿床矿物学及稳定同位素特征

铁木里克铁矿是西天山阿吾拉勒成矿带上一个高品位的磁铁矿矿床,赋存于石炭纪大哈拉军山组火山岩中。矿区围岩蚀变较弱,主要以低温热液阶段的绿泥石化和绿帘石化为主。根据野外矿石组构以及镜下观察,该矿床可以划分为四个成矿阶段。目前该矿床的研究程度较低,矿床成因存在较大争议。磁铁矿和赤铁矿的电子探针结果显示,该矿床的形成与岩浆-热液系统密切相关;辉石和角闪石的电子探针结果显示,辉石未发生蚀变,只有角闪石轻微地发生了阳起石化。矿石中的黄铁矿硫同位素(0.1‰~2.9‰)显示具有深源地幔特征,磁铁矿的氧同位素(-2.7‰~0.5‰)暗示岩浆热液对成矿具有重要作用,以及成矿晚期低温热液过程对早先形成的磁铁矿起到了改造作用。结合区域铁矿带的成矿地质特征,本文认为铁木里克铁矿的形成主要与岩浆-热液系统密切相关,在大量磁铁矿形成之后,有少量成矿流体与海水混合,对矿床和围岩进行了低温热液蚀变,形成了充填在磁铁矿矿石气孔中的赤铁矿和黄铁矿。     

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。     

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.     

坡麓地带工程勘察应注意的问题

在坡麓地带进行工程勘察时，应注意论证工程建设对工程地质环境的改变，评价其对设计、施工的适宜性和可行性，采取相应的工程技术措施。     

我国水产品国际竞争力的提升策略

当前我国水产品出口屡屡受挫．如何提升我国水产品的国际竞争力是我们面临的一个重要课题。通过分析认为。制约我国水产品国际竞争力的外部因素：发达国家技术壁垒的强化；反倾销、反补贴和特殊保障措施使我国在保护水产品生产和贸易上处于严重的不利地位；生态标签成为新的非关税壁垒，威胁着国际贸易的发展。内部因素：政府管理体制方面的制约；水产品生产加工方面的制约；行业组织化程度低，恶性竞争没有得到有效遏制；生产服务和信息服务能力弱；水产品市场体系的制约因索。在此基础上，提出了增加政府补贴、加强养殖监管、健全合作组织、实施品牌战略等一系列提升我国水产品国际竞争力的策略。