Preliminary study on Middle Pliocene pollen flora of Yushe Basin, Shanxi Province, North China
Liu Geng-wu, Estella B. Leopold, Liu Yun, Wang Wei-ming, Yu Zi-ye and Tong Guo-bang
pp. 51-63, 2 plates, in English, with Chinese abstract
Well-exposed Pliocene outcrops in the Yushe Basin of Shanxi Province, North China, yield rich pollen and spore fossils. The Middle Pliocene pollen flora of the Yushe Basin is dominated by Artemisia, Chenopodiaceae, Ulmus and Pinaceae pollen. Betula, Corylus, Carpinus, Quercus, Salix, Gramineae and undifferentiated compositae pollen are present in different quantities. Exotic plants, mainly including Juglans/Pterocarya, Carya and Carpinus, are significant minor elements. Spores in the pollen flora are generally rare. Such a pollen flora probably indicates that the Middle Pliocene vegetation in the Yushe area is deciduous broad-leaved forest with conifer trees or mixed conifer and deciduous broad-leaved forest. The climate of that time was seasonally dry and not very humid. The warm index curve of the study area shows a declining temperature trend between 3.1 Ma and 2.3 Ma with several oscillations, which probably implies an increasing intensity of glaciations. This curve also indicates a warm phase at about 3.1 Ma and a cooling event at about 2.5 Ma in the Yushe area of North China.
Keywords: Palynology, Pliocene, Yushe Basin, Shanxi, palaeoclimate