湘南黄沙坪矿床两类岩体成矿差异性及成矿物质来源研究
发布时间：2019-05-23 17:09
【摘要】：黄沙坪矿床是湘南地区最大的铅锌矿床。矿区内岩浆活动复杂,矿化类型齐全,成矿元素多样,是湘南地区斑岩-矽卡岩-热液脉型Cu多金属与W-Sn多金属复合成矿作用的典型代表。矿区两种岩体(石英斑岩和花岗斑岩)的成矿差异是矿区多金属复合成矿形成的基础,且其较小的岩体出露却造成矿区大规模成矿也一直备受关注,成矿物质来源长期存在争议。为初步查明矿区两类成矿岩体的成矿差异原因、探讨矿区成矿物质硫的来源问题,此次分别从同位素年代学、同位素地球化学、元素地球化学及矿物微区等角度对矿区不同花岗质岩石的年代学特征、岩石成因差异及硫同位素特征方面开展了相关研究工作。在成岩年代学方面,通过对黄沙坪矿区的不同类型花岗岩进行了系统的锆石LA-ICP-MS U-Pb定年和Hf同位素组成研究显示,英安斑岩、花岗斑岩和石英斑岩的侵位年龄分别为158.5±0.9 Ma、155.2±0.4 Ma、160.8±1.0 Ma,不同花岗质岩石中锆石的εHf(t)值为-3.2~-7.6,Hf同位素两阶段模式年龄为1.7~1.4Ga,即该区花岗质岩浆主要源自中元古代的古老基底物质部分熔融;结果表明黄沙坪矿区不同类型花岗质岩石的锆石年龄和Hf同位素特征表明,英安斑岩、花岗斑岩、石英斑岩可能是同源同时期不同阶段岩浆演化的产物,与矿床成矿年龄(154~159 Ma)接近,反映其成岩成矿具有密切的时空联系。在岩石成因与岩浆性质方面,本文在前人研究的基础上,从两类成矿岩体的空间分布特征、岩石地球化学特征、主要特征矿物(长石、黑云母)和副矿物锆石的微区特征等方面对比岩浆形成机制发现,石英斑岩和花岗斑岩在空间侵位、岩浆分异演化程度和形成条件(温度、氧逸度等)方面均存在差异。分析表明石英斑岩具有的高侵位特征、相对较高的氧逸度和较低的形成温度可能是矿区Cu矿形成的关键,而高分异、还原性的高温花岗斑岩岩浆可能是矿区W-Mo-Sn矿形成的重要原因。在成矿物质来源方面,本次研究在已有工作的基础上,对黄沙坪矿区石英斑岩和花岗斑岩进行了系统的全岩硫同位素分析,并与已有硫化物硫同位素数据进行了对比研究。结果显示,矿区石英斑岩和花岗斑岩的δ34S范围分别为+4.1‰~+7.5‰和+4.9‰~+11.4‰,与典型的S型花岗岩硫同位素组成基本一致,而明显低于区内矿石δ34S值(+2.3‰~+17.5‰)。综合上述,我们认为矿区岩浆硫的同位素组成应接近或略低于花岗质岩石全岩硫同位素组成,成矿物质硫除部分来自岩浆外,很大程度上有地层或膏盐层硫的加入,这可能是黄沙坪成为区域上最大铅锌多金属矿床的重要原因。
[Abstract]:Huangshaping deposit is the largest lead-zinc deposit in southern Hunan. The magmatic activity in the mining area is complex, the mineralization type is complete, and the metallogenic elements are various, which is a typical representative of the composite mineralization of Cu and W-Sn in southern Hunan. The metallogenic difference between the two kinds of rock mass (quartz porphyry and granite porphyry) is the basis of the formation of multi-metal composite mineralization in the mining area, and the large-scale mineralization in the mining area has been paid more and more attention because of the emergence of its smaller rock mass. The source of metallogenic materials has long been controversial. In order to find out the reasons for the metallogenic differences between the two types of metallogenic rocks in the mining area, and to explore the source of ore-forming sulfur in the mining area, the isotopic chronology and isotopic geochemistry are respectively discussed. The chronological characteristics, genetic differences and sulfur isotopic characteristics of different granitic rocks in the mining area have been studied from the point of view of element geochemistry and mineral microarea. In the aspect of diagenetic chronology, the zircon LA-ICP-MS U-Pb dating and Hf isotopic composition of different types of granites in Huangshaping mining area have been systematically studied. The emplacement ages of granitic porphyry and quartz porphyry are 158.5 卤0.9 Ma,155.2 卤0.4 Ma,160.8 卤1.0 Ma, respectively. The 蔚 Hf (t) values of zircon in different granitic rocks are-3.2 鈮，
本文编号：2484070
[Abstract]:Huangshaping deposit is the largest lead-zinc deposit in southern Hunan. The magmatic activity in the mining area is complex, the mineralization type is complete, and the metallogenic elements are various, which is a typical representative of the composite mineralization of Cu and W-Sn in southern Hunan. The metallogenic difference between the two kinds of rock mass (quartz porphyry and granite porphyry) is the basis of the formation of multi-metal composite mineralization in the mining area, and the large-scale mineralization in the mining area has been paid more and more attention because of the emergence of its smaller rock mass. The source of metallogenic materials has long been controversial. In order to find out the reasons for the metallogenic differences between the two types of metallogenic rocks in the mining area, and to explore the source of ore-forming sulfur in the mining area, the isotopic chronology and isotopic geochemistry are respectively discussed. The chronological characteristics, genetic differences and sulfur isotopic characteristics of different granitic rocks in the mining area have been studied from the point of view of element geochemistry and mineral microarea. In the aspect of diagenetic chronology, the zircon LA-ICP-MS U-Pb dating and Hf isotopic composition of different types of granites in Huangshaping mining area have been systematically studied. The emplacement ages of granitic porphyry and quartz porphyry are 158.5 卤0.9 Ma,155.2 卤0.4 Ma,160.8 卤1.0 Ma, respectively. The 蔚 Hf (t) values of zircon in different granitic rocks are-3.2 鈮，
本文编号：2484070
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