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苍山龙宝山地区碱性杂岩体金成矿特征研究

Study of Gold Mineralization Features of Alkaline Complex Rock Mass in Longbaoshan Area of Cangshan Country

【作者】 董广莹

【导师】 杨锋杰;

【作者基本信息】 山东科技大学 , 矿产普查与勘探, 2011, 硕士

【摘要】 龙宝山中生代燕山早期的岩浆活动产生于火山弧后拉张环境中,与中国东部橄榄安粗岩岩浆活动密切有关,最初可能均源于上地幔的同一岩浆房,幔源岩浆同化了一定数量的地壳物质后结晶形成了壳幔混源产物,并从中淬取了部分有益组分。剧烈的构造运动为金元素的活化、迁移、富集、沉淀提供了通道和成矿空间。太古宙变质岩系是本区金成矿的初始矿源层。综合考虑该岩体内部含有大量寒武系捕掳体和接触带角砾岩等的热动力构造现象,论文推断龙宝山岩体为本区金成矿作用提供了重要的矿源和热源。龙宝山地区金矿床在早白垩世晚期到晚白垩世早期成矿,龙宝山成矿年龄(含矿石英脉中长石K-Ar)为96.2Ma。成矿流体具有低温、低盐度的特点。区内沉积岩多表现为微磁性和无磁性,高精度磁测反映为平稳的磁场;侵入岩类多表现为磁性不均匀,在高精度磁测结果上反映为突变的磁场。在金矿床周围,金及与金密切相关的元素含量明显升高。从土壤元素地球化学图上可以看出,Au元素异常均以小型局部异常形式分布,比较分散,幅值低,浓集中心不明显。为进行研究,本次论文还在苍山地区布置了7条岩石地球化学剖面,分别在二道湾、西马山、东马山、吴家沟、义和庄、晒钱埠、西大埠。其中吴家沟剖面Au、Ag、Pb三种元素的含量有较好前景;义和庄剖面的灰岩和粉砂质泥页岩,尤其是灰岩中Ag、Cu、Pb、Zn、As、Sb、Bi这7种元素的前景非常好;西大埠剖面闪长玢岩中Au含量也较高;二道湾、东马山、晒钱埠剖面中,金及多金属元素仅显示弱异常;西马山剖面8种元素均很低,无进一步工作价值。龙宝山地区金矿床按其赋存部位与矿化特征不同可分为褐铁矿化石英脉型、蚀变角砾岩型、侵入角砾岩型、褐铁矿化硅化砂岩型四种矿化类型。莲子汪-晒钱埠地区金矿化可分为矽卡岩型、破碎带蚀变岩型和石英脉型。

【Abstract】 Magmatic activities of Longbaoshan area in Mesozoic Early Yanshan stage are formed in the volcanic back-arc tensional environment, closely related to magmatic activity of shoshonitic rocks in eastern China, which might initially come from the same magma chamber of the upper mantle, mantle-derived magmas assimilated a number of crusts and crystallized into crust-mantle mixed-source products and obtained some useful components. Intense tectonic movements provide channel and mineralization space for the activation, migration, enrichment and sedimentation of gold elements. Archean metamorphic rocks are the initial ore source of gold mineralization in this area. Considering thermal power structures phenomena that there are a large number of Cambrian xenoliths and aureole breccia in the rock mass, the thesis infers that Longbaoshan rock mass provides important mineral sources and heart source for the gold mineralization in this area. Gold deposits in Longbaoshan mineralized in the late Early Cretaceous to early Late Cretaceous and the mineralization age of Longbaoshan (including quartz veins feldspar K-Ar) is 96.2Ma. Ore-forming fluid is of low temperature and low salinity.In this area, sedimentary rocks show micro-magnetic and non-magnetic and high-precision magnetic survey reflects a stable magnetic field; intrusive rocks show unevenly in magnetism and high-precision magnetic test results reflect mutation in magnetic field. Around the ore deposits, the contents of gold and its related elements significantly increase. According to the soil elements geochemical map, the anomalies of element Au distribute in small local anomalies, scattered, low amplitude and of no obvious concentration centers.For the purpose of researches, the thesis also arranged seven lithogeochemistry profiles in Cangshan area, respectively in Erdaowan, Ximashan, Dongmashan, Wujiagou, Yihezhuang, Shaiqianzhuang, Xidabu. Among them, the contents of Au, Ag, Pb in Wujiagou profile are 40.89、31.30、11.85 times of the contents in upper crust, with good prospect; limestone and silty shale in Yihezhuang profile, especially Ag, Cu, Pb, Zn, As, Sb and Bi in limestone, have very good prospect; the content of Au in diorite porphyrite in Xidabu profile is also very high; gold and multi metallic elements only show weak anomaly in Erdaowan, Dongmashan and Shaiqianbu profiles; contents of all the eight elements in Ximashan profile are very low and of no worth for further study.According to the difference in storage place and mineralization features, Longbaoshan area could be divided into limonitization quartz vein, altered breccia, intrusive breccia and limonite silicified sandstone. Gold ore mineralization in Lianziwang-Shaiqianbu could be divided into skarn, crushed zone altered rock and quartz vein.

【关键词】 岩体金矿成矿特征地球化学龙宝山
【Key words】 rockgold oremineralization featuresgeochemistryLongbaoshan
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