What triggers the transition of palaeoenvironmental patterns in China, the Tibetan Plateau uplift or the Paratethys Sea retreat?

Geological research has illustrated the transition of palaeoenvironmental patterns by the earliest Miocene from a planetary-wind-dominant type to a monsoon-dominant type, indicating that the East Asian monsoon became markedly intensified and played a leading role in the East Asian climate. From a modeling point of view, the pioneering research using the reduced number of scenarios had demonstrated that both the Tibetan Plateau uplift and the Paratethys Sea retreat were important for understanding the Asian monsoon evolution. However, the sensitivity of the Paratethys retreat to the East Asian climate still needs further studies based on the more detailed scenarios. Thirty numerical experiments under the six Paratethys Sea and the five Tibetan Plateau conditions illustrate the shifts from zonal climate to the monsoon climate in East Asia. The results confirm again that both the Paratethys retreat and the Tibetan plateau uplift play important roles in the formation of the monsoon-dominant environmental pattern, and show that the Paratethys retreat can strengthen the East Asian monsoon and greatly increase humidity and aridity respectively in the monsoon areas and Northwest China, which is similar to the impact of the Tibetan Plateau uplift on the East Asian climate. Furthermore, the fact that the Paratethys Sea retreats to the Turan Plate is found to be the key criterion for the palaeoenvironmental patterns' transition in China. The shrinkage of Paratethys Sea leads to the reconstructions of the pressure system and the atmospheric circulations, which result in the variations of precipitation and the transition of palaeoenvironmental patterns. (c) 2006 Elsevier B.V All rights reserved.