| 藏南雅鲁藏布江大竹卡组砾岩沉积时代的年龄约束 |
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| 关键词:Dazhuka Formation Gangdese Thrust System volcanic rock interlayers zircon U-Pb dating ESR dating |
| 基金项目:中国地质调查局项目“羌塘盆地油气资源调查评价与战略选区”(编号: DD20233002)；“地质调查科技创新发展与新技术推广研究”(编号: DD20221829)；“全国油气重点调查区战略性矿产调查评价”(编号: DD20233001) |
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| Constraints on the Depositional Age of the Dazhuka Conglomerate along the Yarlung Zangbo River, Southern Tibet |
| The Dazhuka Formation, distributed in an east–west belt along the Yarlung Zangbo River in Tibet, comprises a sedimentary sequence of varicolored multi-component sandy conglomerates. This formation is geologically significant for understanding the evolution of the Yarlung Zangbo Suture Zone and the tectonic configuration. To date, there are no reliable sedimentary age data for this stratum. This study discovered volcanic rock interlayers and andesite veins in the Xigaze segment within the Dazhuka Group by geological field survey and conducted zircon U-Pb isotopic age tests. By combining the electron spin resonance (ESR) age of quartz veins during synsedimentary structural deformation in the Gyaca segment with K-Ar isotopic dating of the underlying tuffaceous limestone, we further constrained the sedimentary age of the Dazhuka Formation. These results indicated that the Dazhuka Formation is diachronous. The sedimentary age of the Dazhuka Formation strata outcropping in Xigaze is (30.74±0.71) Ma, corresponding to Early to Middle Oligocene, and is primarily influenced by the Gangdese Thrust System. However, the ages of the main sedimentary phase outcropping in the Zedang–Gyaca segment are concentrated in the Early to Middle Miocene, with the lower limit of the sedimentary age being no earlier than (27.77±2.59) Ma. Intense structural deformation occurred between 27 Ma and 21 Ma in coincidence with the active period of the Gangdese Thrust Fault, indicating that the sedimentation of Dazhuka Formation was also influenced by the Gangdese Thrust System in the western segment. |
| YANG Yan,ZHAO Zhen.2024.Constraints on the Depositional Age of the Dazhuka Conglomerate along the Yarlung Zangbo River, Southern Tibet[J].Acta Geoscientica Sinica,45(6):893-902. |
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