Search

Currently, the climatic implications associated with the Cenozoic tectonic history and growth mechanisms of the Tibetan Plateau lack consensus and remain controversial. This is due in part to chronological uncertainties and few paleoelevation records distributed in the central to northern Tibetan Plateau, which we address here with the development of a robust chronology (using magnetostratigraphy, biostratigraphy, detrital zircons, and regional radiochronologic dating) and a paleoelevation reconstruction for the Tuotuohe Basin (central-northern Tibet). We refined the age of the Tuotuohe Formation (37-33 Ma), Yaxicuo Formation (33-23.6 Ma), and Wudaoliang Formation (23.6-19.7 Ma). We estimated early Oligocene (ca. 29 Ma) paleotemperatures of the Tuotuohe Basin from 11 °C to 16.1 °C, which correspond to paleoelevations of 2.9 km (±0.4 km) when the relative humidity is 64% and 2.5 km (±0.5 km) when this value is 75%, using various methods including ostracod assemblages, gastropods, charophytes, branched glycerol dialkyl glycerol tetraether analysis, regional empirical formulas, and climate model simulation. Paleoelevation data and existing geological evidence in the vicinity indicate that late Eocene to late Oligocene uplift was associated with upper-crustal shortening. Since the middle Miocene, uplift has been associated with convective removal of lithospheric mantle and/or lower-crustal flow beneath the Hoh Xil Basin. [ABSTRACT FROM AUTHOR]

This article demonstrates that the above-normal Tibetan Plateau snow depth ( TPSD) in winter appears to be followed by an intensified Philippine Sea anticyclone in June ( PSAC-J), and vice versa. This linkage is clearly independent of the relationship between the El Niño-Southern Oscillation ( ENSO) and the PSAC-J. Moreover, winter TPSD anomalies are typically associated with a PSAC-J pattern that shifts northwards compared with that associated with ENSO. A better understanding of the combined effects of the winter TPSD and ENSO on the PSAC-J could improve our ability to predict both the East Asia summer monsoon and variations in the Meiyu-Changma-Baiu rainbelt. [ABSTRACT FROM AUTHOR]

It has been proposed that the northeastern Tibetan Plateau (NETP) was the most recent plateau sub-region to gain elevation, leading to profound environmental changes in northern East Asia around the mid-Pliocene (ca. 3.6 Ma). Alternatively, environmental changes in the region have been linked to ongoing global cooling and glacial intensification after 3.3 Ma. Here, we test these hypotheses using Plio-Pleistocene estimates of paleotemperatures and paleoelevations in the NETP derived from oxygen and carbon stable isotopic composition (n = 792) and clumped isotope measurements (n = 32) of carbonates from a Lake Qinghai Basin sediment core, eastern NETP. From 5 to 2 Ma, basinal mean annual air temperatures (MAATs) decreased by 4.9 ± 2.8 °C at rates of 1.6 °C ± 0.5 °C/myr, concurrently with regional and global cooling. However, the largest MAAT decline occurs between ca. 4.8-3.7 Ma (4.1 ± 3.2 °C) and ca. 3.4-2.0 Ma (-0.3 ± 2.8 °C) and may correspond with an elevation change of 1.0 ± 1.0 km at 3.6 Ma, coincident with tectonic activity in the Lake Qinghai Basin and several other basins in the NETP and its foreland. Taken together, these results suggest a combination of global cooling and a small magnitude of surface uplift (<1 km) at ca. 3.6 Ma may have contributed to the regional evolution of climate in the Lake Qinghai Basin. [ABSTRACT FROM AUTHOR]