Distinguishing climate from tectonic forcing in shaping the Earth’s surface has been a long-standing issue in the Earth sciences. Great debate exists regarding when and how the SE Tibetan Plateau achieved its current low-relief topography, and both lateral extrusion and lower crust flow have been proposed as the dominant mechanism. Reconstruction of the exhumation history of the SE Tibetan Plateau is key to understanding these formation processes and resolving the significance of different forcing mechanisms. Here we report zircon and apatite (U-Th)/He ages from steep transects across the Lincang granite belt of the SE Tibetan Plateau. Our results reveal a two-stage exhumation history during the Cenozoic with rapid cooling phases in the late Eocene and the middle Miocene. In the late Eocene, the climate was generally dry and there is plenty of evidence for increased extrusion and upper crustal shortening. We suggest tectonic processes are responsible for the first inferred cooling. In contrast, the Asian summer monsoon precipitation increased during the middle Miocene, and we posit the middle Miocene cooling phase records a phase of rapid river incision triggered by the intensified precipitation and associated fault movements. The results are consistent with recent paleo-altimetry work in this region suggesting that the present-day topography of the SE Tibetan Plateau had been largely constructed by the late Eocene. Together, these data suggest that extrusion and/or upper crustal shortening setup the first order topography of the SE Tibetan Plateau, which was then modified by climate-triggered fluvial incision and feedbacks initiated in the middle Miocene.

中文翻译：

---

区分景观演化的构造与气候强迫：以东南青藏高原为例

在构造地球表面的过程中，从构造强迫中区分气候是地球科学中长期存在的问题。关于青藏高原东南部何时以及如何实现其目前的低起伏地貌存在着巨大的争论，并且侧向挤压和地壳流动减少被认为是主导机制。重建东南青藏高原的发掘历史是了解这些形成过程和解决不同强迫机制意义的关键。在这里，我们报道了青藏高原东南部临沧花岗岩带陡峭断面的锆石和磷灰石（U-Th）/ He年龄。我们的结果揭示了在新生代晚期和中新世中期快速冷却阶段的两阶段发掘历史。在始新世晚期 气候总体上是干燥的，有大量证据表明挤压增加和地壳缩短。我们建议构造过程是造成第一个推断冷却的原因。相反，在中新世中期，亚洲夏季风降水增加，并且我们假设中新世中期冷却期记录了由降水增加和相关断层运动触发的快速河道切入阶段。结果与该地区最近的古测高工作是一致的，这表明东南部青藏高原的当今地形主要是由始新世晚期构造的。这些数据共同表明，挤压和/或上地壳缩短是东南青藏高原的一阶地形，