Paleoelevation of Tibetan Lunpola basin in the Oligocene–Miocene transition estimated from leaf wax lipid dual isotopes

Abstract

Carbon and hydrogen isotopic compositions of leaf wax n-alkanes are promising paleoelevation proxies. In this paper, the two proxies were applied to the Dingqing Formation in the Lunpola basin in the central Tibetan Plateau to reconstruct paleoelevation of the basin from the latest Oligocene to the early Miocene. Values of δ13C and δD of C29n-alkane were −29.8±0.7‰ (n=38) and −188±10‰ (n=22), respectively. Using the δ13C and δ18O of the early Miocene Siwalik paleosol carbonate in south Asia as lowland references, paleoelevation of ~3000m was independently estimated from the two isotopic proxies. The results are consistent with recent estimates from pollen and mammal fossil studies. Furthermore, the time-series leaf wax δ13C and δD records consistently suggest a reduction of ~900m from 25.5Ma to 21.6Ma, which is likely associated with rapid erosion or tectonic unroofing.