| Popis: |
Pliocene climate is regarded as an analogue of future global warming (Burke et al, 2018; IPCC, 2021). How was the Pliocene precipitation in the monsoonal East Asia is not well known, although the Pliocene eolian silt ‘Red Clay’ deposit sequences have been investigated (Gallagher et al., 2021; Wang et al., 2022.). The poor preservation of floral and fauna fossils, and low sedimentation rate of the Red Clay makes it inappropriate to use as proxies that quantitatively reconstructing the Pliocene paleoclimate. In this study, a thick lacustrine deposit sequence at the Taigu-Yushe Basin (TYB) in central China is investigated, in order to semi-quantitatively reconstruct the East Asian monsoon precipitation variations during the Pliocene and early Pleistocene. These lacustrine sediments are rich in fossils. The thick lacustrine deposit sequences are dated by paleomagnetic stratigraphy analysis and correlated with the loess-paleosol time-series. The results show that the TYB lake deposit was accumulated during circa 4.0 -1.5 Ma. The Xiaobai Formation, which indicates a humid climate, was formed during 4.0-2.4 Ma. The pollen assemblage of the lake deposits and fluvial sediments reveals a dry climate after 2.4 Ma. Our proxy analyses show the precipitation during the middle Pliocene was 30% more than the present. This sedimentary record unravels the strengthened East Asian monsoon circulation which transported more vapor to the monsoon marginal during the Pliocene warmth. |
