钦杭成矿带中段花岗质岩浆演化对铜多金属成矿作用的制约--以湘南宝山铜矿为例

Qinzhou-Hangzhou ore belt is an important ore belt recently recognized in South China, in which the Mesozoic Cu-polymetallic mineralization is with unique characteristic in China. Southern Hunan Province, located in the central section of the Qin-Hang ore belt, is critical area for connecting two large-scale clusters of porphyry Cu deposits in the south and north part of the Qin-hang ore belt, respectively. However, the metal mineral assembly, mineralization-style and its ore deposit sizes are significantly different with those of the south and north part in Qin-hang ore belt, which is an important issue need to be addressed. This proposal will take the representative Baoshan Cu-polymetallic deposit as an example. Based on previous studies, we will focus on the source and evolution process of magma and associated Cu-polymetallic mineralization, and systematically conduct the studies of petrology, ore mineralogy, elemental and isotopic geochemistry, and fluid geochemistry. Based on the above, we will try to further constrain the characteristics of source region, redox state and the emplacement depth of the ore-bearing magma, in turn, we will do some comparative studies with the south and north parts of the Qin-hang ore belt, and reveal the crucial factors controlling the differences of the metal mineral assembly, mineralization-style and its ore deposit sizes in different part from the same ore belt. The study will undoubtedly provide significant insights to understand the Cu-polymetallic metallogenic processes and metallogenic regularity of the Qin-hang ore belt, which will further enrich the intra-continental porphyry-style Cu-polymetallic metallogenic theory, as well as to guide to ore-prespecting in the central section of the Qin-Hang ore belt.

钦杭成矿带是近年新识别出来的一条重要成矿带，其中生代铜多金属成矿在我国独具特色。湘南地区位于钦杭成矿带的中段，是衔接该成矿带南北两大斑岩成矿区的关键部位。但该区铜多金属矿床在矿种组合、矿化类型及成矿规模上均与南北两端明显不同，这种成矿差异性是有待查明的重要科学问题。本申请拟以该区最具代表性的宝山铜矿为解剖对象，以含岩浆的形成、演化与成矿过程为主线，系统开展岩石学、矿床学、元素及同位素地球化学和流体地球化学的研究，试图查明含矿岩浆的源区性质、氧化还原状态、岩体侵位深度及岩浆-热液演化成矿过程，并与成矿带南北两端进行对比，以揭示钦杭成矿带不同区段在矿种组合、矿化类型及成矿规模上存在明显差异的内在原因。该项目的开展，无疑将进一步深化对整个钦杭成矿带铜多金属成矿过程和成矿规律的认识，这有助于丰富我国陆内斑岩铜矿的理论研究，而且可为钦杭成矿带中段铜多金属找矿勘查提供理论依据。

湘南地区位于华南NE向钦杭成矿带和EW向南岭成矿带的叠合部位，花岗岩浆活动强烈，类型多样，并伴有大规模的钨锡铜铅锌银多金属成矿，是研究花岗岩浆作用及其成矿效应的理想场所。本项目以区内宝山、铜山岭及七宝山铜多金属矿床为主要研究对象，系统开展年代学、岩石地球化学及矿床学的研究，并对比研究了区内同时代的钨锡多金属矿床和钦杭带内不同区段代表性铜多金属矿床成矿作用，取得了以下几点认识：（1）通过对钦杭成矿带系统的Hf-O同位素填图，结合年代学及岩石地球化学的研究，明确岩浆源区性质是制约钦杭成矿带不同区段成矿差异的重要控制因素，并提出钦杭成矿带南北两端高Hf值区有利于大型铜多金属矿床的形成，中段低Hf值区域有利于大型铅锌矿床的形成；并根据典型矿床成岩成矿深度及流体包裹体组合的对比研究，认为湘南地区成铜岩体相对南北两端侵位深度较大，不利于斑岩型矿床的发育，是该区铜多金属矿以矽卡岩型为主的重要原因。（2）通过对湘南钨锡矿和铜铅锌矿的对比研究，认为尽管该区近于同时在同一区段形成了复杂的有色金属成矿作用，但钨锡矿与铜铅锌矿的成矿岩体岩浆源区特征、岩浆性质及分异演化程度均存在明显差异，是中晚侏罗世特定构造环境下两套成矿体系在两个成矿带叠合部位叠加成矿的产物。（3）对比研究了湘南东坡超大型钨锡多金属矿田，明确巨量金属富集成矿可以在1-2Ma完成，矿田范围内钨锡铅锌为同一成矿体系演化的结果，并根据围岩性质的差异，构建了矿田尺度钨锡铅锌矿床组合模型，为区域找矿勘查部署提供重要依据。（4）基于湘南地区大花岗岩基周缘最新找矿成果，系统解剖研究了彭公庙-桂东大花岗岩基周缘钨锡矿床的成因，明确该区产于大花岗岩内部及边缘的钨锡矿均形成于晚侏罗世，指出该区深部具有良好的晚侏罗世钨锡矿找矿前景，并通过系统对比研究成钨锡矿的高分异小岩体与大花岗岩基的岩石地球化学特征，明确大花岗岩基侵位深度大、分异程度低，并经历强烈的抬升剥蚀过程，钨锡成矿潜力有限，产于大花岗岩基内部及周缘的钨锡矿应与晚期高分异的小岩体有关，为围绕大花岗岩找矿勘查提供重要理论依据。.基于上述研究工作，目前共发表本项目批注学术论文19篇，其中SCI论文11篇（含国际SCI论文7篇），国内核心期刊论文6篇，国际会议摘要论文2篇，另外投稿《Mineralium Deposita》论文1篇，投稿《岩石学报》论文3篇。