Variations in Exhumation as Evidence of Climate Divergence and Historical Uplift of the Tibetan Plateau

The uplift of the Tibetan Plateau is crucial for understanding both regional and global climate dynamics. This uplift, and the interplay between climate and tectonics, profoundly influences surface exhumation. The creation of a climatic divide due to mountain uplift results in starkly different weather patterns, with the windward side receiving more precipitation and the leeward side forming drier rain shadows. These climatic differences have consequential long-term impacts on exhumation, and therefore, are key to our understanding historical mountain landscapes like the Himalayas and the Andes. This study explores these distinct exhumation as indicators of ancient mountain ranges. By integrating new and existing apatite fission track (AFT) and apatite helium (AHe) data, we reveal exhumation's spatial variability across the plateau, providing insights into its geological history. The discernible disparities suggest a high-elevation watershed divide near the current latitude of ~31°N existed before the Eocene, influencing precipitation and exhumation in the plateau’s southern regions. The northern regions, in the lee of this divide, show reduced exhumation rates, except in areas of tectonic activity. High exhumation rates at the plateau's orogenic front zones suggest these boundaries locations are key to understanding its expansion; tracking these zones gives clues about the plateau's growth. While pinpointing the onset of higher exhumation is complex due to continuous tectonic activity, focusing on the expansion of the interior—represented by a slower exhumation zone—proves more revealing. Our research indicates that the plateau expanded bilaterally from the latitude ~31°N and implicates the Tibetan Plateau's development since the Eocene as a factor in the Earth's climatic evolution, potentially influencing global cooling.