Unroofing and uplift history of the Yungui Plateau at SE Tibetan Plateau, evidence from detrital zircon and apatite thermochronometry

In response to the Indo-Asian collision, the eastward growth of Tibetan Plateau results into an extensive low-relief surface in the Yunnan-Guizhou area, i.e., the Yungui Plateau. Of which the paradoxical presence of extensive low-relief surface perched above deep valleys in the southeast Tibet Plateau is a long-standing challenge. Here, we apply 36 samples detrital zircon and apatite thermochronometry along the Yangtze and Nanpanjiang rivers, to provide the reginal-scale proxy for the unroofing and uplift history of the Yungui Plateau. The detrital zircon fission track data range in age from Permian to Cretaceous, with major peak-ages at 200 Ma, 160 Ma, 140 Ma, and 120 Ma along different rivers, indicating of a single phase of westwards unroofing along the Yungui Plateau occurred in ca. 160-120 Ma. Furthermore, detrital apatite fission track data shows major peak-ages at 60 Ma, 40 Ma and 20 Ma, with ages of various from 100~10 Ma. In particular, detrital apatite (U-Th)/He data shows major peak-ages around 10 Ma along the Xianshuihe-Xiaojiang area, with regional erosion more than 1500 m. The results confirm overall southwards unroofing process occurred in Late Cenozoic, from southeast margin of the Tibetan Plateau to the Yungui Plateau interiors. Thus, the Yungui Plateau surface uplift and incision result from two processes, expanding the Eastern Tibetan Plateau into its low-relief high-elevation surface along the Yungui Plateau.