Aridification signatures from fossil pollen indicate a drying climate in east-central Tibet during the late Eocene

作者：Qin Yuan, Natasha Barbolini, Catarina Rydin, Donglin Gao, Haicheng Wei, Qishun Fan, Zhanjie Qin, Yongsheng Du, Junjie Shan, Fashou Shan, Vivi Vajda · 发表于：Climate of the past · 年份：2020 · DOI：10.5194/cp-16-2255-2020 · 被引用次数：20 · 研究领域：Geology and Paleoclimatology Research、Geological and Geochemical Analysis、Plant Diversity and Evolution

Abstract. Central Asia experienced a number of significant elevational and climatic changes during the Cenozoic, but much remains to be understood regarding the timing and driving mechanisms of these changes as well as their influence on ancient ecosystems. Here, we describe the palaeoecology and palaeoclimate of a new section from the Nangqian Basin in Tibet, north-western China, dated as Bartonian (41.2–37.8 Ma; late Eocene) based on our palynological analyses. Located on the east-central part of what is today the Tibetan Plateau, this section is excellently placed for better understanding the palaeoecological history of Tibet following the Indo-Asian collision. Our new palynological record reveals that a strongly seasonal steppe–desert ecosystem characterized by drought-tolerant shrubs, diverse ferns, and an underlying component of broad-leaved forests existed in east-central Tibet during the Eocene, influenced by a southern monsoon. A transient warming event, possibly the middle Eocene climatic optimum (MECO; 40 Ma), is reflected in our record by a temporary increase in regional tropical taxa and a concurrent decrease in steppe–desert vegetation. In the late Eocene, a drying signature in the palynological record is linked to proto-Paratethys Sea retreat, which caused widespread long-term aridification across the region. To better distinguish between local climatic variation and farther-reaching drivers of Central Asian palaeoclimate and elevation, we correlated key palyno...