LATE PLIOCENE TEMPERATURE RECONSTRUCTIONS IN THE SE TIBETAN PLATEAU

The late Pliocene spans a time with warmer conditions than today. It has been observed from both marine and terrestrial realms in a global scale. However, regional temperatures from the late Pliocene is far from well-known. The present study quantitatively reconstructed the late Pliocene temperatures in SE Tibetan Plateau based on palaeobotanical data compiled from published resources using the Coexistence Approach (CA). The reconstructed mean annual temperatures (MATs) indicate slightly warmer conditions during the late Pliocene than today. Latitudinal gradients in temperature appears steep in this region during the late Pliocene, which might reflect altitudinal gradients that the northern part was higher than the southern part at that time. Unlike other territories, summer temperature decrease is most pronounced in SE Tibetan Plateau since the late Pliocene. This probably resulted from the eastern extension of the Tibetan Plateau and precipitation changes. The eastern extension of the Tibetan Plateau might resulted in the overall orogenic uplift in this region and strengthened the summer cooling. On the other hand, the extended eastern Tibetan Plateau forced cold high pressure migrate along the eastern flank of the plateau in winter, which weakened the Asian winter monsoon in the study area and buffered the winter cooling. Moreover, the increasing summer precipitation strengthened the summer cooling, while the decreasing winter precipitation buffered the winter cooling trend.