PP21B-2243
Late Cenozoic genus Fupingopollenites development and its implications for the Asian summer monsoon (ASM) evolution

Tuesday, 15 December 2015
Poster Hall (Moscone South)
Yunfa Miao1, Chunhui Song2, Xiaomin Fang3, Qingquan Meng2, Ping Zhang4, Fuli Wu3 and Xiaoli Yan2, (1)Chinese Academy of Sciences, Beijing, China, (2)Lanzhou University, Lanzhou, China, (3)ITP Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China, (4)Key Laboratory of Earth Fissures Geological Disaster, Ministry of Land and Resources; Geological Survey of Jiangsu Province, Nanjing, China
Abstract:
An extinct palynomorph, Fupingopollenites, was used as the basis for a discussion of the late Cenozoic Asian summer monsoon (ASM) evolution and its possible driving forces. Based on the spatial and temporal variations in its percentages across Inner and East Asia, we found that Fupingopollenites mainly occurred in East Asia, with boundaries to the NE of ca. 42°N, 135°E and NW of ca. 36°N, 103°E during the Early Miocene (ca. 23-17 Ma). This region enlarged westwards, reaching the eastern Qaidam Basin (ca. 36°N, 97.5°E) during the Middle Miocene (ca. 17-11 Ma), before noticeably retreating to a region bounded to the NW at ca. 33°N, 105°E during ca. 11-5.3 Ma. The region then shrank further in the Pliocene, with the NE boundary shrinking southwards to about 35°N, 120°E; the area then almost disappeared during the Pleistocene (2.6-0 Ma). The flourishing and subsequent extinction of Fupingopollenites is indicative of a narrow ecological amplitude with a critical dependence on habitat humidity and temperature (most likely mean annual precipitation (MAP) >1000 mm and mean annual temperature (MAT) >10°C). Therefore, the Fupingopollenites geographic distribution can indicate the humid ASM evolution during the late Cenozoic, revealing that the strongest ASM period occurred during the Middle Miocene Climate Optimum (MMCO, ~17-14 Ma), after which the ASM weakened coincident with global cooling. We argue that the global cooling played a critical role in the ASM evolution, while the Tibetan Plateau uplifts made a relatively small contribution. This result was supported by a Miocene pollen record at the Qaidam Basin, inner Asia and the contemporaneously compiled pollen records across the Eurasia.