沂沭断裂带中段典型金矿床成因及成矿年代学研究

Yi-Shu fault belt is the boundary of the two large gold ore concentration areas of Jiaodong and western Shandong, only few medium and small sized gold deposits, such as Longquanzhan, Nanxiaoyao, and Niujiaxiaohe, have been discovered in the middle section of it. The lack of the study on the ore genesis of gold deposits in Yi-Shu fault belt is one of the important reasons that do not make a breakthrough in prospecting for gold deposit in this area. This project will study the metallogenetic epoch of altered rock type and quartz vein type gold ore bodies by the isotopic dating of pyrite Re-Os, pyrite Rb-Sr, mica Ar-Ar and quartz fluid inclusion Rb-Sr for gold-bearing mineral of pyrite, quartz and mica closely related to gold mineralization in three typical gold deposits in the middle section of the Yi-Shu fault belt; Trace the sources of ore-forming materials and fluids, study systematically ore genesis of gold deposits in this area , according to the research and analysis for the isotope of S, Pb, He and Ar in gold-bearing pyrite and H, O and C in fluid inclusions of gold-bearing quartz, element geochemistry and isotope data from the isotope geochronology. The research result may provide theoretical guidance for prospecting of the gold deposit in this area.

沂沭断裂带作为胶东与鲁西两个大型金矿矿集区的分界，目前仅在其中段有龙泉站、南小尧和牛家小河等几处中小型金矿床。之所以在沂沭断裂带中段没有较大的金矿找矿突破，对该区金矿成因研究的缺乏是重要原因之一。该项目将以沂沭断裂带三个典型金矿床蚀变岩型与石英脉型金矿体中与金成矿密切相关的载金矿物黄铁矿、石英、云母进行黄铁矿Re-Os、黄铁矿Rb-Sr、云母Ar-Ar、石英流体包裹体Rb-Sr同位素定年工作来确定蚀变岩型和石英脉型两种矿体的成矿时代；通过对载金矿物黄铁矿S、Pb、He、Ar同位素，石英的H、O同位素及其流体包裹体中CO2的C同位素，元素地球化学及定年所获同位素资料的研究分析，限定成矿物质、成矿流体的来源及性质，系统研究该区金矿成因，为进一步找矿勘探提供理论指导。

沂沭断裂带作为胶东与鲁西两个大型金矿集中区的分界，目前仅在其中段有龙泉站、南小尧和牛家小河等几处中小型金矿床。之所以在沂沭断裂带中段没有较大的金矿找矿突破，对该区金矿成因研究的缺乏是重要原因之一。该项目对沂沭断裂带南小尧、夏家小河、牛家小河等金矿床及胶西北招贤金矿进行了详细的野外考察，并选择与金成矿关系密切的载金矿物、脉石矿物、蚀变围岩，进行元素地球化学、黄铁矿原位微量元素、S同位素及He、Ar同位素地球化学研究。结果表明，沂沭断裂带中段金矿成矿物质来源于沂水岩群；成矿流体呈现壳幔混合的特征，但主要来源于地壳，同时少量大气降水参与了成矿作用，沂水岩群与成矿关系密切，除了提供成矿物质外，也提供了部分成矿流体。而胶西北招贤金矿成矿物质来源于深部，玲珑花岗岩与郭家岭花岗岩可能为其提供了成矿物质，成矿流体具有壳幔流体混合的特征，早期以变质流体为主，主成矿期岩浆活动起主导作用，并有有限的大气饱和水的参与，末期成矿流体为地壳流体。相关认识对区内进一步找矿勘探及研究具有一定的参考和借鉴价值。