文章摘要
魏 宇.四川甘洛铅锌矿集区闪锌矿Rb-Sr等时线年龄及其地质意义[J].地质与勘探,2024,60(3):482-493
四川甘洛铅锌矿集区闪锌矿Rb-Sr等时线年龄及其地质意义
Rb-Sr isochron ages of sphalerites from the Ganluo lead-zinc ore concentration area in Sichuan Province and their geological implications
投稿时间:2022-09-04  修订日期:2023-10-13
DOI:10.12134/j.dzykt.2024.03.004
中文关键词: 闪锌矿 Rb-Sr等时线年龄 成矿时代 物质来源 甘洛铅锌矿集区 四川
英文关键词: sphalerite, Rb-Sr isochron age, metallogenic epoch, source of ore-forming materials, Ganluo ore concentration area, Sichuan Province
基金项目:四川省自然资源厅科研项目(编号:KJ-2023-19)资助
作者单位E-mail
魏 宇 四川省冶金地质勘查院四川成都
四川省自然资源投资集团有限责任公司四川成都 
305918483@qq.com 
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中文摘要:
      四川甘洛铅锌矿集区位于扬子地块西南缘的川滇黔铅锌成矿带北段,是四川主要的铅锌产地,具有重要经济价值。为研究该矿集区铅锌成矿时代、成矿大地构造背景和成矿机制,以支撑区域找矿勘查,在区内选择赤普和尔呷地吉两个典型铅锌矿床开展闪锌矿Rb-Sr同位素体系研究,获得Rb-Sr等时线年龄246 ± 17 Ma(MSWD= 2.3),表明区内铅锌矿化作用发生于早三叠世,与古特提斯洋闭合时限吻合;闪锌矿(87Sr/86Sr)i值变化于0.71061~0.71393,高于幔源87Sr/86Sr值0.70355及峨眉山玄武岩87Sr /86Sr值0.704979~0.706938,低于基底岩石87Sr /86Sr值0.7243~0.7288,暗示成矿物质主要来源于地壳。综合前人研究,认为在古特提斯洋闭合背景下,强烈造山运动诱发盆地卤水深循环并萃取基底地层中的成矿物质,在峨眉山玄武岩岩浆活动的热动力条件下,含矿流体沿马拉哈断裂进一步迁移沉淀形成了赤普和尔呷地吉铅锌矿床。马拉哈深大断裂及造山作用派生的层间或断层破碎带、碳酸盐岩地层是甘洛地区主要的控矿要素。
英文摘要:
      The Ganluo lead-zinc ore concentration area is located north of the Sichuan-Yunnan-Guizhou Pb-Zn metallogenic belt along the southwestern margin of the Yangtze Massif, which is a major Pb-Zn producing area in Sichuan Province with significant economic value. This work aims to clarify the metallogenic epoch, geotectonic setting, and the Pb-Zn mineralization mechanism, and thus to support the regional mineral exploration. Rb-Sr isotopic dating of sphalerites was conducted on the Chipu and Ergadiji Pb-Zn deposits. The Rb-Sr dating yielded an isochron age of 246±17 Ma (MSWD=2.3), which indicates the Pb-Zn mineralization occurred in the Early Triassic. This age coincides well with the closure epoch of the Paleo-tethys Ocean. Sphalerite (87Sr/86Sr)i values vary from 0.71061 to 0.71393, which are greater than the mantle 87Sr/86Sr value of 0.70355 and that of Emeishan basalt of 0.704979 to 0.706938, but smaller than the 87Sr/86Sr values of basement rock of 0.7243 to 0.7288. The mineralized materials were suggested to be mainly originated from the crust. Combined with previous research, it is indicated that under the background of Paleo-Tethys Ocean closure, the strong orogeny induced the deep circulation of brine fluids in foreland basin and extracted mineralized materials from the basement rocks. Under the thermodynamic condition of Emeishan basalt, the mineralized fluids further migrated and precipitated to form the Chipu and Ergadiji Pb-Zn deposits. The Malaha deep fault, interlayer or fault fractures derived from the orogeny and the carbonate strata are the dominant ore-controlling factors in the Ganluo area.
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