| 藏北商旭金矿床的碎屑锆石U-Pb年龄及其地质意义 |
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| 关键词:detrital zircons Bangong Co–Nujiang suture zone Qiangtang terrane Shangxu in Tibet |
| 基金项目:国家重点研发计划(深地资源勘查开采)(编号: 2016YFC0600306);国家重点基础研究发展计划(973计划)(编号: 2011CB403104);中国地质调查局地质调查项目(编号: 12120113037901; DD20160026; DD20179142);国家科技支撑计划(编号: 2006BAB01A04) |
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| Tracing the Provenance of Detrital Zircons from the Shangxu Gold Deposit in Northern Tibet |
| The Shangxu gold deposit is located on the southern side of the middle part of the Bangong Co–Nujiang suture zone in northern Tibet. In this paper, the authors conducted in situ U-Pb dating of detrital zircons from the Middle–Lower Jurassic metasedimentary rocks in Shangxu for tracing their provenance. The analysis of 114 detrital zircons of varied sizes and shapes, which were selected randomly, shows that: (1) zircons are 80~150 μm long, and Th/U ratios of most zircons are higher than 0.4; (2) ages of detrital zircons range from 223 Ma to 2 615 Ma, with five peaks of ca. 280 Ma, ca. 451 Ma, ca. 908 Ma, ca. 1 900 Ma and ca. 2 430 Ma. By contrasting detrital zircon ages for the Middle–Lower Jurassic metasedimentary rocks in Shangxu with those in Lhasa and southern Qiangtang terranes, an important observation is that the ca. 908 Ma age population characteristic of detrital zircons in Shangxu is consistent with the distinctive ca.950 Ma age peak in detrital zircons from the western Qiangtang terrane, rather than distinctive ca. 1 170 Ma age peak in detrital zircons from the Lhasa terrane. The authors hold that the age (223 Ma) is close to the depositional age. The result indicates that the provenance of Middle–Lower Jurassic Mugagangri Group in Shangxu probably is the remnant of the Bangong Co–Nujiang oceanic basin, implying the northward subduction of the Bangong Co–Nujiang Ocean beneath southern Qiangtang terrane. |
| PEI Ying-ru,YANG Zhu-sen,ZHAO Xiao-yan,MA Wang,ZHANG Xiong,MAO Jing-tao.2017.Tracing the Provenance of Detrital Zircons from the Shangxu Gold Deposit in Northern Tibet[J].Acta Geoscientica Sinica,38(5):711-722. |
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