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引用本文:龚银杰,张遵遵,陈立波,金世超,甘金木,漆双林. 川东南褶皱带洞岩铅锌矿床闪锌矿Rb-Sr同位素测年及其构造变形时代[J]. 中国地质, 2020, 47(2): 485-496.
GONG Yinjie,ZHANG Zunzun,CHEN Libo,JIN Shichao,GAN Jinmu,QI Shuanglin. Sphalerite Rb-Sr isotopic dating of the Dongyan Pb-Zn deposit in Southeastern Sichuan fold belt and its constraint on the timing of tectonic deformation[J]. Geology in China, 2020, 47(2): 485-496(in Chinese with English abstract).
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川东南褶皱带洞岩铅锌矿床闪锌矿Rb-Sr同位素测年及其构造变形时代
龚银杰1, 张遵遵1, 陈立波2, 金世超1, 甘金木1, 漆双林3
1.中国地质调查局武汉地质调查中心, 湖北 武汉 430205;2.湖北省地质局第八地质大队, 湖北 襄阳 441703;3.中南冶金地质研究所, 湖北 宜昌 443003
摘要:
重庆西阳县洞岩铅锌矿床位于川东南褶皱带中,为一中低温热液铅锌矿床,预测Zn金属量10.14万t。矿(化)体主要沿NNE向、NWW向断层呈脉状分布,或沿层间破碎带呈似层状分布。赋矿围岩为奥陶系碳酸盐岩。川东南褶皱带中这一类型铅锌矿床的形成时代以及与NNE向断层相互关系研究薄弱。本文运用闪锌矿Rb-Sr同位素测年方法,测得洞岩铅锌矿床成矿年龄为(157.7±3.3)Ma,表明该矿床的主成矿阶段年龄为晚侏罗世。闪锌矿(87Sr/86Sr)i值为0.71347,远高于早期及同期沉积碳酸盐比值,可能与大气淡水加入有关。川东南褶皱带为推覆-滑脱的薄皮构造,褶皱变形的主要时期为中晚侏罗世的燕山运动早期。洞岩闪锌矿的Rb-Sr等线年龄与上述构造变形时代一致,说明矿床的形成与早燕山构造变形事件有关。
关键词:  闪锌矿Rb-Sr定年  铅锌矿  燕山期  地质调查工程  川东南褶皱带
DOI:10.12029/gc20200215
分类号:
基金项目:中国地质调查局地质大调查项目(DD20179232)资助。
Sphalerite Rb-Sr isotopic dating of the Dongyan Pb-Zn deposit in Southeastern Sichuan fold belt and its constraint on the timing of tectonic deformation
GONG Yinjie1, ZHANG Zunzun1, CHEN Libo2, JIN Shichao1, GAN Jinmu1, QI Shuanglin3
1.Wuhan Center, China Geological Survey, Wuhan 430205, Hubei, China;2.No.8 Geological Party, Hubei Geological Bureau, Xiangyang 441703, Hubei, China;3.Central South Institute of Geology and Metallurgy, Yichang 443003, Hubei, China
Abstract:
The Dongyan Pb-Zn deposit located in the Southeast Sichuan folded belt is a middle-low temperature hydrothermal type lead and zinc deposit, predicted amount of Zn metal is 101400 tons. The orebodies occur along NNE- and NWW-trending faults in veined or stratoid form in the interlayer fracture zone and are hosted in Ordovician carbonate rocks. The formation of this type of Pb-Zn deposit in the southeastern Sichuan fold belt and the relationship with the NNE-trending fault remain unclear. In this paper, Rb-Sr isotopic dating yielded an age of (157.7±3.3) Ma for the sphalerite in the Dongyan Pb-Zn deposit, which represents the main metallogenic age of this deposit and also constrains the formation time of NNE-trending fault of this area. The (87Sr/86Sr)i ratio of the sphalerite is 0.71347, which is much more higher than the ratios of the same period or earlier period, and might have been related to atmospheric freshwater. The Southeast Sichuan folded belt of Sichuan Basin is a nappe-detachment thin skinned structure. The main period of the fold deformation was the early Yanshanian stage in the Middle-Late Jurassic period. Rb-Sr isochron age of Dongyan sphalerites is consistent with the tectonic deformation age mentioned above, indicating that the formation of the deposit was related to the Early tectonic deformation in Yanshanian stage.
Key words:  Rb-Sr isochron age of sphalerites  Pb-Zn deposit  Yanshanian stage  geological survey engineering  Southeast Sichuan folded belt