延边东部“庙岭组火山岩”及其对铜多金属成矿作用与构造背景的制约

The Miaoling Formation Volcanic Rock, having been classified primarily into the late Paleozoic Maioling Formation, is major ore-hosting rock of such suspected VMS copper polymetallic deposits in Yanbian area as Hongtaiping deposit in Wangqing area and Dongfengnanshan deposit in Longjing, and can provide key information for ore genesis of these deposits. Moreover, it is very significant to reveal the late Paleozoic tectonic setting of the Eastern Yanbian. In order to determine the Paleozoic tectonic setting and ore genesis of these suspected VMS copper polymetallic deposits, this research program mainly involves Miaoling Formation Volcanic Rock and associated polymetallic deposits. Firstly, by field geologic survey, stratigraphic section and petrographic study, rock type, lithology combination and rock sequence of Miaoling Formation will be ascertained, and the volcanic rock, makeable exhalite and their relationships with the copper polymetallic mineralization will be studied. Secondly, isotope dating and element-isotope geochemical tracer will be used to research the geochemical characteristics of the volcanic rock and contemporaneous intrusive rock, which may constrain the material source and tectonic setting of relevant magmatism. Thirdly, geological survey of mine area, mineral and rock identification, mineral microanalysis, microthermometry and laser Raman spectroscopy analysis of the fluid inclusion, isotope dating, as well as elemental and isotopic geochemistry will be carried out, so that Hongtaiping and Dongfengnanshan deposits can intensively studied, involving their ore-forming conditions, metallogenic epoch, mineralization and alteration zoning, ore-forming fluid and ore-forming materials, as well as metallogenic mechanism. These researches are very helpful for determining the geological age, tectonic setting of the Miaoling Formation Volcanic Rock and its constrains on such suspected VMS type copper polymetallic deposits. It can also answer the key question that such deposits as Hongtaiping and Dongfengnanshan,hosted in the late Paleozoic volcanic rocks in Yanbian area , are VMS type or not. The major scientific object is to reveal the Late Paleozoic tectonic setting of the study area from both magmatic rock and deposit perspectives.

“庙岭组火山岩”是指原划归二叠系庙岭组的火山岩系，作为红太平和天宝山东风南山等疑似VMS型铜多金属矿床的主要含矿岩系，是甄别此类矿床成因类型和探究成矿机理的关键，对揭示延边东部晚古生代构造环境也具有重要意义。本项目以“庙岭组火山岩”及与之有关的多金属矿床为研究重点，通过路线调查、剖面实测和岩石学研究，查明庙岭组中的火山岩系、特殊喷气岩及它们与铜多金属矿化的时空关系；利用同位素测年及元素-同位素地球化学示踪技术，揭示火山岩和同时代侵入岩的岩浆源区和构造背景；解剖性研究红太平和东风南山矿床，划分成矿期次，厘定不同成矿期的成矿地质条件、物理化学条件、物质来源、成矿机制与形成时代。最终明确庙岭组火山岩系的形成时代、构造背景及其对铜多金属成矿作用的制约，解决“红太平和东风南山多金属矿床是否为VMS型”这一关键科学问题，实现“从火成岩和矿床学角度揭示延边东部晚古生代大地构造环境”的科学目标。

延边东部庙岭组火山岩系是红太平和天宝山东风南山等疑似VMS型铜多金属矿床的含矿建造，是研究这些矿床成因的关键。项目以庙岭组火山岩系及所含矿床为研究重点，研究内容包括火山岩系的地质地球化学特征、岩浆源区、构造背景、与疑似VMS型矿床的成因联系，以及红太平和东风南山矿床的成矿条件、矿化特征、成矿期次、成因类型、物质源区、形成时代与构造背景。取得的重要成果有：（1）查明了庙岭组火山岩系为浅海相中酸性火山岩-火山碎屑岩-碳酸盐岩-陆源碎屑岩建造，发育硅质岩、萤石、锌尖晶石等喷气岩类（矿物）。（2）根据庙岭组火山岩富集轻稀土元素和大离子亲石元素，亏损高场强元素，判断其初始岩浆源于中-新元古代新生下地壳的部分熔融，并混入少量幔源物质。（3）测得4件庙岭组火山岩样品的锆石U-Pb年龄为265.0±1.8Ma~278.5±1.3Ma，根据火山岩及同时代侵入岩的岩性组合、地球化学特征及区域构造演化资料，明确早-中二叠世研究区处于古亚洲洋俯冲背景下的活动大陆边缘环境。（4）认为红太平和东风南山矿区庙岭组火山岩系中的层状矿体，具有VMS型矿床的地质地球化学特征，以及黑矿型的成矿地质条件和构造背景。（5）首次获得红太平层状矿体的硫化物Rb-Sr等时线年龄为268.3±2.6Ma，东风南山层状矿体含矿建造中硅质岩的锆石U-Pb年龄为267.0±1.2Ma；红太平矿区切割层状矿体的脉状矿体的硫化物Rb-Sr等时线年龄为206.8±9.0Ma，与脉状矿体时空及成因关系密切的花岗闪长斑岩脉锆石U-Pb年龄为204.1±2.0Ma。（6）基于红太平和东风南山矿床的两期成矿特征，建立了延边地区喷流沉积-叠加改造成矿模式。本项研究厘定了延边东部晚古生代VMS型成矿事件及其构造背景，为该区VMS型成矿理论研究、成矿规律总结和资源潜力评价提供了理论和资料基础，因此具有重要的理论和实际意义。