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中国有色金属学报

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第28卷    第12期    总第237期    2018年12月

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文章编号:1004-0609(2018)-12-2598-12
江西永平十字头钼矿床辉钼矿Re-Os年龄及其地质意义
邵拥军1, 2,彭南海1, 2, 3,汪 程1, 2,张 宇4,刘忠法1, 2

(1. 中南大学 有色金属成矿预测与地质环境监测教育部重点实验室,长沙 410083;
2. 中南大学 地球科学与信息物理学院,长沙 410083;
3. 有色金属矿产地质调查中心,北京 100012;
4. 中国科学院广州地球化学研究所,广州 510640
)

摘 要: 江西永平十字头钼矿床为钦杭成矿带北东段上新近发现的一个斑岩型钼矿床,钼矿体主要赋存于似斑状黑云母花岗岩体与周潭组混合岩系的外接触带中,受岩体和构造控制。本文对该矿床石英-硫化物脉中的辉钼矿进行了Re-Os同位素测年,获得辉钼矿Re-Os模式年龄为(156.9±2.2) Ma ~(158.5±2.4) Ma之间,加权平均值为(158±1) Ma,等时线年龄为(158.0±2.5) Ma。十字头钼矿床中辉钼矿的Re含量为65.05×10-6~150.20×10-6,指示该矿床的成矿物质来源具有壳幔混源的属性。对比本区成岩与成矿的年龄,并结合该矿床的地质特征及地球化学特征,认为本区成矿与似斑状黑云母花岗岩有密切的亲缘关系,二者属于相同地球动力学背景下同一地质-构造-岩浆事件的产物。结合前人对钦杭带北东段的研究成果,认为钦杭北东段存在172~145Ma和140~130Ma两期钼的成矿事件。两期成矿事件的时限与华南地区中晚侏罗世和白垩世两大成矿高峰期一致,它们分别是对Izanagi板块向欧亚大陆之下低角度俯冲有关的弧后局部伸展和Izanagi俯冲板块沿NE方向快速走滑的响应。

 

关键词: 十字头钼矿床;辉钼矿;Re-Os同位素测年;成矿年龄;成岩成矿关系;成矿动力学背景

Re-Os isotopic chronology and geological significance of olybdenites in Shizitou molybdenum deposit, Yongping, Jiangxi province, China
SHAO Yong-jun1, 2, PENG Nan-hai1, 2, 3, WANG Cheng1, 2, ZHNAG Yu4, LIU Zhong-fa1, 2

1. Key Laboratory of Metallogenic Prediction of Non-ferrous Metals and Geological Environment Monitoring(Central South University), Ministry of Education, , Changsha 410083, China;
2. School of Geo-sciences and Info-physics, Central South University, Changsha 410083, China;
3. China Non-ferrous Metals Geological Survey, Beijing 100012, China;
4. Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China

Abstract:The Shizitou Mo deposit in Yongping, Jiangxi is a recently discovered important deposit in the eastern section of the Qin-Hang metallogenic belt. The Mo deposit mainly occurs in the outer contact zone between the porphyraceous biotite granite and the Zhoutan group migmatite, and is mainly controlled by the rock body and structures. Re-Os dating of molybdenite gives a model age of (156.9±2.2) Ma-(158.5±2.4) Ma, with a weighed mean age of (158±1) Ma, and gives an isochron age of (158.0±2.5) Ma. The Re content of the molybdenite is 65.05×10-6-150.20×10-6, indicating that the ore-forming materials have mantle-crust mixed features. Based on the comparison between the ore-forming age and the rock-forming age of the deposit area, and by looking into the geological features and geochemical features of the deposit, it is concluded that the ore-forming process of the area is closely linked with the porphyraceous bioite granite rock body, and that both the deposit and the rock body are products of the same geological-tectonic-magmatic event under the same dynamic background. Based on previous studies in the northeastern section of the Qinhang metallogenic belt, it is believed that two episodes of Mo ore-forming events at 172-145 Ma and 140-130 Ma have occurred in the northeastern section of the Qinhang metallogenic belt. The time of the two episodes of ore-forming events corresponds with the two ore-forming peak periods in late Jurassic and Cretaceous, in response to the back-arc partial extension associated with the low-angle subduction of the Izanagi plate beneath the Eurasia plate and the quick NE striking slipping of the Izanagi subduction plate.

 

Key words: Shizitou molybdenum deposit; molybdenite; Re-Os isotopic chronology; metallogenic age; metallogenic- diagenetic relationship; metallogenic dynamic setting

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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