【作者】 刘丽；

【导师】 顾雪祥；

【作者基本信息】 中国地质大学（北京） ， 矿物学岩石学矿床学， 2009， 硕士

【摘要】 沂南金矿床位于华北板块东南缘沂沭断裂带西侧的鲁西地区,管辖相距6km的铜井和金场两矿区,是一个典型的夕卡岩型矿床。矿床产于燕山期中酸性～酸性杂岩体的接触带及外侧的新元古界—寒武系围岩中,受岩浆岩、构造、地层和围岩蚀变的共同控制。NW与NE、NEE向断裂构造交汇部位控制成矿岩体的就位,控矿和容矿的构造主要为接触带构造、层间破碎带构造及不整合面构造等。矿床分为四个成矿阶段:干夕卡岩阶段、湿夕卡岩-磁铁矿阶段、氧化物-硫化物阶段和碳酸盐阶段。近年来,在矿区深部和外围发现了新的含矿层位和工业矿体,但在流体包裹体方面前人未曾开展过研究,从而制约了对矿床成因和成矿规律的深入认识。本文从流体包裹体出发,讨论了沂南矿床的成矿物质来源和成矿机制。各成矿阶段的矽卡岩矿物、石英和方解石中流体包裹体岩相学和显微测温研究结果表明,包裹体主要类型有气液水包裹体、含子矿物多相包裹体、CO2-H2O多相包裹体和晶质熔融包裹体,其中熔体包裹体在石榴石、绿帘石和石英中发育。Ⅰ、Ⅱ成矿阶段的成矿流体具有高温和高盐度的特征,均一温度分别为430～520℃、340～400℃,盐度分别为56.7 wt% NaCl、22.2～53.5 wt% NaCl,代表铁矿化时流体特征;Ⅲ成矿阶段流体具有中低温、盐度范围变化较大的特征,代表了Cu,Au矿化的流体活动情况。均一温度为190℃～250℃,盐度为6.45～53.5 wt% NaCl ;Ⅳ成矿阶段包裹体均一温度100℃～190℃,盐度为2.07～15.76 wt% NaCl。矿床的成矿作用发生在0.6～1.7km的浅成条件下。其中石榴石、绿帘石中的熔融包裹体的出现是岩浆成因夕卡岩的证据。根据不同类型包裹体共生组合及流体演化特征,认为流体的不混溶性是导致大量金属沉淀的主要原因。包裹体水的氢氧同位素结果表明,成矿流体主要来自于岩浆热液,晚期不同程度的大气降水混入。更多还原

【Abstract】 As a typical skarn deposit in the western Shandong Province, the Yinan gold deposit is located on the west side of Yishu fault zone. It includes the Tongjing and Jinchang ore districts which are 6 km away from each other. The deposit is controlled by magma, strata lithology, wall rock alteration and structure. The location of the ore-forming intrusions were controlled by the intersecting places between the NW and NE or the NW and NEE trending fault structures .The ore-controlling and ore-bearing structures mainly include contact zone, interlayer fractured zone and unconformity structure,etc. The metalogenic processes can be devided into the anhydrous skarn stage, the hydrous skarn-magnetite stage, the oxide-sulfide stage and the carbonate stage. In the recent years, new ore layers have been discovered, but the investigations on the fluid inclusions of the deposit which restrict the ore genesis and metallogenic laws is urently needed.Based on the fluid inclusion study, this paper made further discussions on the source of ore-forming materials and ore genesis of the deposit. Petrographic observations and temperature results indicate that the main type of fluid inclusions are aqueous inclusions, CO2-H2O inclusions, crystalline melt inclusion and daughter mineral-bearing multiphase in four mineralization stages. Melt inclusions were recognized in garnet, epidote and quartz. In the first and second mineralization stage, the ore-forming fluid is characterized by high temperature and high salinity , homogenization temperature is 430℃～510℃and 330～390℃respectively with salinity 56.7 wt% NaCl and 2.2～53.5 wt% NaCl respectively, indicating the fluid activities during Fe mineralization; In the third mineralization stage, the ore-forming fluid is salinities(6.45～53.5 wt% NaCl ); In the last stage, the homogenization temperature ranged from 130℃to 190℃, with salinity from 2.07 to 15.76 wt% NaCl. The mineralization occurred under the epithermal conditions of 0.6～1.7km.The appearance of the melt inclusions in garnet and epidote is the evidence of magmatic skarn.The assemblage of different fluid inclusions and the evolution characteristics of fluid inclusion show that fluid immiscibility is the main cause for mineralization. The composition of H and O isotopes shows that the ore-forming fluids were mainly magmatic hydrothermal fluids and were mixed with meteoric water during the later mineralization stage.更多还原