| 辽东五龙金矿床构造控矿特征和辉钼矿Re-Os年龄 |
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| 引用本文： | 肖昌浩,刘向冲,赵岩,张青,陈正乐,刘建民,韦昌山,姚晓峰,王伟,解丽强.辽东五龙金矿床构造控矿特征和辉钼矿Re-Os年龄[J].地球科学,2020,45(11):3982-3997. |
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| 作者姓名： | 肖昌浩 刘向冲 赵岩 张青 陈正乐 刘建民 韦昌山 姚晓峰 王伟 解丽强 |
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| 作者单位： | 1.中国地质科学院地质力学研究所动力成岩成矿实验室, 北京 100081 |
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| 基金项目： | 国家重点研发计划项目2018YFC0603802国家自然科学基金项目41702095中国地质调查局项目DD20190161中国地质科学院基本科研业务费JYYWF20180602 |
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| 摘 要： | 五龙金矿床是辽东地区最大的石英脉型金矿床，矿区内矿体和岩脉受断裂构造控制明显.容矿构造几何学和运动学特征显示，早白垩世初近NS向挤压形成的近NS向张裂隙、共轭的剪裂隙及派生一对共轭剪裂隙奠定五龙金矿床的构造格架.早白垩世的伸展导致闪长岩脉、三股流岩体、五龙背岩体等沿着先存构造薄弱带内充填，出溶的岩浆热液流体沿着闪长岩充填残余空间继续充填形成石英脉.由于右形剪切变形导致石英脉发生碎裂，并伴随着区域伸展，赋存闪长岩脉和石英脉的构造空间复活，随后花岗岩脉等侵位及出溶的成矿流体通过闪长岩脉上侵的通道运移和充填于石英脉裂隙中并交代闪长岩脉和片麻状二长花岗岩，最后造就了岩脉-矿化-蚀变同构造空间共存的现象.通过成矿期运动学特征显示，NE向断裂带与胶东三山岛金矿带矿体群侧伏规律相似，断裂带北段深部具有找矿潜力.五龙矿区而言，NE向断裂的找矿潜力优于NW向断裂带，NE向断裂下盘平行断裂内张性空间是盲矿体的有利空间.本次首次获得了五龙金矿床辉钼矿-黄铁矿-磁黄铁矿-石英阶段辉钼矿Re-Os同位素模式年龄为125±2.1 Ma.辉钼矿中Re含量为12.8×10-6，显示成矿物质具有壳幔混合的特征.对比前人研究，钼矿化和金成矿均与早白垩世构造体制转换下中国东部强烈的壳幔岩浆活动有关，为同一构造背景下的产物.通过对比胶东地区的成矿系列，辽东地区与胶东地区具有极大的相似性，存在两期钼矿化作用，尤其早白垩世晚期钼矿化可以作为寻找金矿的标志之一.
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| 关 键 词： | 控矿构造 辉钼矿Re-Os测年 五龙金矿床 辽东 胶东 地质年代学 |
| 收稿时间： | 2020-07-23 |
Structural Controls and Re-Os Dating of Molybdenite of Wulong Gold Deposit,NE China |
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| Abstract: | The Wulong gold deposit is one of the most representative quartz-vein gold deposits in the Liaodong district in the NE China. The ore bodies and dikes are controlled by faults. The geometry,kinematics and kinetics characteristics of the ore-bearing structures indicate that the structural framework in the Wulong gold district is composed of the N-S tensile fracture,several NE-striking sinistral and NW-striking dextral conjugate faults and associated conjugate riedal fractures caused by the nearly N-S compression at the beginning of the Early Cretaceous. The diorites,Sanguliu pluton and Wulongbei pluton intruded into the pre-existing structures and NE-striking normal faults accompanied with the NW-SE extension during the Early Cretaceous. Hydrothermal fluid exsolution from the Early Cretaceous magmas migrated into the residual space in the fractures which were intruded by diorite. The dextral shear deformation led to the break of the quartz. The fractures infilled by granite dikes and quartz vines reactivated and the ore-forming fluids were characterized by vertical transport and lateral replacement in these fractures. The fluids infilled into the fractures of the broken quartz and replaced the Early Cretaceous dikes and gneissic monzonite granite. Therefore,the auriferous quartz veins share the similar space with the previous quartz and dikes. Kinetic characteristics of the ore-bearing structures indicate that the north of the NE-striking faults has the exploration potential and has a similar regularity for lateral trending of orebodies in the Sanshandao gold belt,Jiaodong district. In the Wulong gold district,the exploration potential of NE-striking faults is better than in the NW-striking faults and the tensile fractures in the footwall blocks of NE-striking faults are the advantageous space for searching for the concealed orebodies. This study first defines a molybdenite Re-Os isotopic model age of 125 ±2.1 Ma for the molybdenite-pyrite-pyrrhotite-quartz stage which represents the major ore-forming stage of the Wulong gold deposit. The Re concentrations of the molybdenite is 12.8×10-6,suggesting that ore-forming material contained a mixture of crustal and mantle components. The comparison of previous studies indicate that both of the molybdenum and gold mineralization are related with the intense crust-mantle magma activity in NE China. In comparison with the metallogenic series in the Jiaodong district,both of the Liaodong and Jiaodong have two stages of molybdenum mineralization. Especially,the late of the Early Cretaceous molybdenum mineralization could be one of the clues for gold prespecting in the Liaodong district. |
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