西藏列廷冈铁多金属矿床矿物学特征及其地质意义

发布时间：2018-10-29 19:39

【摘要】：列廷冈铁多金属矿床位于西藏林周盆地西北缘,隶属堆龙德庆县德庆乡管辖,大地构造位置位于冈底斯弧背断隆带,是林周盆地Fe-Mo-Cu-Pb-Zn矿集区内近年来新发现的矽卡岩型铁多金属矿床。列廷冈矿床出露地层整体较简单,主要发育三叠系下-中统查曲浦组(T1-2c)碳酸盐岩和第四系(Q)。矿区构造样简单,主要为断裂构造和裂隙构造。矿区侵入岩类型多样,主要有似斑状二长花岗岩、似斑状花岗闪长岩、闪长岩、云斜煌斑岩及斜长角闪岩,与成矿密切相关的岩体为似斑状二长花岗岩和似斑状花岗闪长岩。矿床主要由9个大小、规模、品位不同的矿体组成,主要呈透镜状和不规则状,II号矿体规模最大,矿体主要赋存在似斑状二长花岗岩与碳酸盐岩的接触带及其附近矽卡岩中。结合野外观察、室内综合研究及矿物化学特征综合表明,列廷冈矿床主要发育一套钙质矽卡岩。矽卡岩矿物组合主要为:石榴子石、角闪石、辉石、绿帘石、绿泥石及电气石等。其中,石榴子石属钙铁榴石-钙铝榴石系列(And18.37~99.95Gro0.03~79.05 Ura+Pyr+Spe 0.52~14.47);辉石属于透辉石-钙铁辉石系列(Di53.56~99.91Hd1.61~44.55Jo0.08~5.11);角闪石族主要属钙质角闪石,主要为阳起石+少量铁镁角闪石;绿泥石主要属铁镁绿泥石系列。石榴子石及角闪石矿物化学特征均指示矿床为多金属矿化,这与地质事实相符合。金属矿物种类、组合多样,主要包括磁铁矿、辉钼矿、黄铜矿、黄铁矿、方铅矿、闪锌矿、磁黄铁矿等。其中,磁铁矿是矿床最重要的工业和成因矿石类型,发育块状、浸染状及脉状磁铁矿三种类型,磁铁矿矿物化学特征及成因判别图解综合表明,矿床磁铁矿均属热液磁铁矿型。黄铁矿主要包括自形-它形粒状的普通黄铁矿和同心环带状的胶黄铁矿。基于详实的野外地质调查和室内镜下观察,本文将列廷冈矿床主要划分为矽卡岩期和热液期两个成矿期,进而划分为五个成矿阶段:早期矽卡岩阶段+退化蚀变阶段(矽卡岩期)+早期热液阶段+石英-硫化物阶段+碳酸盐阶段(热液期),不同成矿期及成矿阶段发育不同的矿物组合类型,矽卡岩期矿物组合为:石榴石+角闪石+辉石+绿帘石+电气石等矽卡岩矿物+块状磁铁矿+辉钼矿等金属矿物,热液期矿物组合为:黄铜矿+磁黄铁矿+黄铁矿+方铅矿+闪锌矿等多种金属硫化物。随着成矿过程的不断进行,矽卡岩期→热液期(早期矽卡岩阶段→碳酸盐阶段)的演变,成矿流体的温度、氧逸度、盐度等在不断降低;成矿物理化学条件由相对氧化的环境逐渐演变为相对弱的还原环境,为矿物的生成提供有利条件。
[Abstract]:The Leitinggang iron polymetallic deposit is located in the northwest margin of the Linzhou Basin, Tibet, under the jurisdiction of Deqing Township, Dillongdeqing County, Tibet. The geotectonic location is located in the Gangdis arc back fault uplift zone. It is a skarn type iron polymetallic deposit newly discovered in the Fe-Mo-Cu-Pb-Zn ore concentration area of Linzhou Basin in recent years. The outburst strata of the Letinggang deposit are relatively simple, mainly developed from the Lower Triassic to the Middle Triassic Chajiupu formation (T1-2c) carbonate rocks and Quaternary (Q). The structure of mining area is simple, mainly fault structure and fracture structure. There are various types of intrusive rocks, including porphyry monzogranite, porphyry granodiorite, cloud cline lamprophyre and amphibolite. The ore-forming rock bodies closely related to mineralization are porphyry monzogranite and porphyry granodiorite. The ore deposit is mainly composed of 9 orebodies of different size, size and grade, mainly lenticular and irregular, and the II orebody is the largest. The orebody mainly occurs in the contact zone between porphyry monzogranite and carbonate rock and its adjacent skarn. Combined with field observation, laboratory comprehensive study and mineralogical characteristics, it is shown that a set of calcareous skarn is mainly developed in the Letinggang deposit. The mineral assemblages of skarn are mainly pomegranate, hornblende, pyroxene, verdite, chlorite and tourmaline. Among them, pomegranate belongs to the series of calcium ferrite and calcium aluminite (And18.37~99.95Gro0.03~79.05 Ura Pyr Spe 0.52 ~ 14.47), and pyroxene belongs to the series of diopside and calcium ferroxene (Di53.56~99.91Hd1.61~44.55Jo0.08~5.11). Hornblende family mainly belongs to calcareous hornblende, mainly actinoclase, a small amount of iron and magnesium hornblende, and chlorite mainly belongs to iron-magnesium chlorite series. The mineral and chemical characteristics of pomegranate and amphibole indicate that the deposit is polymetallic mineralization, which is consistent with the geological facts. The types and assemblages of metallic minerals include magnetite molybdenum chalcopyrite pyrite galena sphalerite pyrrhotite and so on. Among them, magnetite is the most important type of industrial and genetic ore in the deposit. There are three types of magnetite, which are massive, disseminated and vein-like magnetite. The synthesis of mineralogical characteristics and genetic discriminant diagram of magnetite shows that the magnetite of the deposit belongs to hydrothermal magnetite type. Pyrite mainly consists of normal pyrite in the shape of automorphism-it-shaped granular pyrite and colloidal pyrite in concentric ring. Based on the detailed field geological survey and indoor microscopic observation, the Letinggang deposit is mainly divided into two metallogenic periods: skarn period and hydrothermal period. Then it can be divided into five metallogenic stages: early skarn stage degenerated alteration stage (skarn stage) early hydrothermal stage quartz-sulphide stage carbonate stage (hydrothermal stage). Different mineral assemblages are developed in different metallogenic and metallogenic stages. The mineral assemblages of skarn stage are garnet hornblende pyroxene opyroxene tourmaline and other skarn minerals such as massive magnetite molybdenum and other metal minerals. Hydrothermal mineral assemblage is chalcopyrite pyrrhotite galena sphalerite and other metal sulfides. With the development of metallogenic process, the temperature, oxygen fugacity and salinity of the ore-forming fluid are decreasing with the evolution of skarn stage (early skarn stage and carbonate stage). The ore-forming physicochemical conditions gradually change from the relatively oxidized environment to the relatively weak reduction environment, which provides favorable conditions for the formation of minerals.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P618.2

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