Quantitatively Tracking the Elevation of the Tibetan Plateau Since the Cretaceous: Insights From Whole-Rock Sr/Y and La/Yb Ratios

Crustal thickness, elevation, and Sr/Y and (La/Yb)_N of magmatic rocks are strongly correlated for subduction-related and collision-related mountain belts. We quantitatively constrain the paleo-elevation of the Tibetan Plateau since the Cretaceous using empirically derived equations. The results are broadly consistent with previous estimates based on stable isotope and structural analyses, supporting a complex uplift history. Our data suggest that a protoplateau formed in central Tibet during the Late Cretaceous and was higher than the contemporaneous Gangdese arc. This protoplateau collapsed before the India-Asia collision, during the same time period that elevation in southern Tibet was increasing. During the India-Asia collision, northern and southern Tibet were uplifted first followed by renewed uplift in central Tibet, which suggests a more complicated uplift history than commonly believed. We contend that a broad paleovalley formed during the Paleogene in central Tibet and that the whole Tibetan Plateau reached present-day elevations during the Miocene.