Characteristics and indication on palaeoclimate of sporopollen assemblages of Mid- to Late- Pleistocene in Sepabayi- Keping Area, Xinjiang

Objective The study of paleo-environmental changes of Mid-to Late-Pleistocene in northwest Tarim Basin is relatively weak. As a sensitive area to climate and environmental change in Asia, the paleoenvironment study of the Southwest Tianshan is of great significance for predicting future climate. The succession law of palaeo-vegetation indicated by the characteristics of palynological assemblage has become an important problem to be solved urgently in paleoclimate research in this area.

Methods Based on palynological identification and photoluminescence dating of typical river terrace samples from Sepayi-Keping area, Xinjiang, the characteristics of palynological assemblages in the Mid-to Late-Pleistocene and their implications for paleoclimate were discussed in this paper.

Results Three palynological assemblages of Mid-to Late- Pleistocene were divided. Palynological assemblage zone Ⅰ: Quercus-Graminae- Chenopodiaceae; Ⅱ: Ephedra-Betula-Labiatae; Ⅲ: Pinus-Ephedra-Chenopodiaceae.

Conclusions They indicate the arid climate of the Southwest Tianshan and the fluctuation trend (dry and cold-warm and wet-dry and cold) during Mid-to Late-Pleistocene. During 65-16 ka before present, there was an obvious humid climate stage with abundant precipitation. The terraces formed by river downcutting were controlled by both tectonic and climatic factors.