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<p>The Cenozoic uplift of the Tibetan Plateau is a pivotal event with profound effects on both regional and global climates. Despite extensive research, the detailed cooling history and exhumation processes of the Gangdese batholith remain poorly constrained, leaving a significant gap in our understanding of the driving forces behind plateau’s uplift. Addressing this gap is crucial for elucidating the tectonic processes that shape the region. In this study, we collected samples from a range of locations within the Gangdese batholith, extending from the Yarlung Zangbo River to the batholith’s interior. Five representative samples from a geological section between 3692 m and 4460 m in elevation were analyzed. Apatite (U-Th)/He ages vary from 5.11±0.42 Ma to 9.11±0.47 Ma, while zircon (U-Th)/He ages from 9.80±7.60 Ma to 14.90±3.20 Ma. Thermal history inversion reveals a two-stage cooling history: an initial phase of stable, rapid cooling from approximately 21 Ma to 6 Ma, followed by divergent cooling paths after ∼6 Ma. Specifically, interior samples exhibit a pronounced decreasing in cooling rates, gradually approaching surface temperatures, whereas the sample from the Yarlung Zangbo River records distinctly rapid cooling. We interpret these contrasting cooling patterns as the result of tectonic processes associated with the break-off and tearing of the Indian plate following the India-Asia collision, in conjunction with fluvial erosion related to the evolution of the Yarlung Zangbo River. The break-off event likely generated substantial plate tearing, resulting in variable subduction angles. In the study area, steep-angle subduction has promoted sustained asthenosphere upwelling, rapid cooling from ∼21 Ma, magmatic activity, and lithospheric delamination within the Lhasa terrane. Around to ∼6 Ma, subsequent break-off episodes appear to have initiated a transition from steep to flat subduction, inhibiting asthenosphere upwelling and reducing the overall cooling rate. The post-6 Ma rapid cooling recorded along the Yarlung Zangbo River is likely attributable to enhanced river incision. Overall, this study provides new insights into the mechanisms of uplift and exhumation in the Tibetan Plateau, demonstrating that the cooling history of the Gangdese batholith is closely linked to the break-off and tearing of the Indian plate.</p>

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Unraveling of the Gangdese batholith exhumation since the Miocene: Evidence from (U-Th)/He thermochronology

  • 期刊论文

  • 发表日期：

    2025年9月17日

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  • Yusheng Zhao,
  • Yuanku Meng,
  • Jingbo Sun,
  • Qingze Gao

摘要

The Cenozoic uplift of the Tibetan Plateau is a pivotal event with profound effects on both regional and global climates. Despite extensive research, the detailed cooling history and exhumation processes of the Gangdese batholith remain poorly constrained, leaving a significant gap in our understanding of the driving forces behind plateau’s uplift. Addressing this gap is crucial for elucidating the tectonic processes that shape the region. In this study, we collected samples from a range of locations within the Gangdese batholith, extending from the Yarlung Zangbo River to the batholith’s interior. Five representative samples from a geological section between 3692 m and 4460 m in elevation were analyzed. Apatite (U-Th)/He ages vary from 5.11±0.42 Ma to 9.11±0.47 Ma, while zircon (U-Th)/He ages from 9.80±7.60 Ma to 14.90±3.20 Ma. Thermal history inversion reveals a two-stage cooling history: an initial phase of stable, rapid cooling from approximately 21 Ma to 6 Ma, followed by divergent cooling paths after ∼6 Ma. Specifically, interior samples exhibit a pronounced decreasing in cooling rates, gradually approaching surface temperatures, whereas the sample from the Yarlung Zangbo River records distinctly rapid cooling. We interpret these contrasting cooling patterns as the result of tectonic processes associated with the break-off and tearing of the Indian plate following the India-Asia collision, in conjunction with fluvial erosion related to the evolution of the Yarlung Zangbo River. The break-off event likely generated substantial plate tearing, resulting in variable subduction angles. In the study area, steep-angle subduction has promoted sustained asthenosphere upwelling, rapid cooling from ∼21 Ma, magmatic activity, and lithospheric delamination within the Lhasa terrane. Around to ∼6 Ma, subsequent break-off episodes appear to have initiated a transition from steep to flat subduction, inhibiting asthenosphere upwelling and reducing the overall cooling rate. The post-6 Ma rapid cooling recorded along the Yarlung Zangbo River is likely attributable to enhanced river incision. Overall, this study provides new insights into the mechanisms of uplift and exhumation in the Tibetan Plateau, demonstrating that the cooling history of the Gangdese batholith is closely linked to the break-off and tearing of the Indian plate.