Modern-like elevation and climate in Tibet since the mid-Miocene (ca. 15 Ma)

Abstract When the modern-like geomorphology and climate pattern of Himalaya-Tibetan Plateau were established still remains unclear. In this study, we apply paired stable isotope compositions carbonate (δ18Oc) leaf waxderived n-alkanes (δ2Halk) from upper Gazhacun Formation in Namling Basin to reconstruct middle Miocene elevation southern Tibet. Depositional age has been precisely constrained between 15.5 Ma 15.1 by zircon U-Pb ages dacite interlayers. Paired derived δ18Ow values (–17.9 ± 1.3‰ –18.3 1.3‰) leaf-wax δ2Hw (–131.5 20‰ –145.7 20‰) plot on or very close global meteoric water line suggesting that these samples experienced little evaporation enrichment isotopic alternation. Based two independent proxies, paleoelevation estimates for are consistently 4.6+0.7/-0.8 km 5.2+0.7/-0.8 km, supporting a high Tibet mid-Miocene. Integrated with published Himalaya, central northern literature, near-present across whole already since (ca. 15 Ma). Besides, show gradually increase northward Himalaya northeastern Tibet, quite similar present day. This suggests during Miocene, Himalaya-Gangdese system may have blocked southerly monsoonal moisture reaching Westerlies local recycling might be dominant sources enriched precipitation could lead erroneous over