Pollen stratigraphy of coal-bearing deposits in the Neogene Jidong Basin,Heilongjiang Province,NE China: New insights on palaeoenvironment and age

The palaeoenvironment and age of coal-bearing lacustrine deposits in the Jidong Basin, Heilongjiang Province, is poorly understood. New pollen data from the Yongqing Formation and the overlying lower part of the Daqingshan Formation recovered in borehole 91-205 revealed a rich and diverse palynoflora representing approximately 70 taxa at the genus/family level. Of these taxa, Ulmus, Quercus, Carya, Liquidambar, Pinus, Tilia, Fagus, and Alnus are the main woody elements; these occur together with numerous pteridophytes, subordinate herbs, and rare algae and acritarchs. Abundant woody taxa suggest a mixed deciduous/conifer forest in the region in association with local shrubs, herbs and algal communities. Some of the pollen types, especially those of climate sensitive genera such as Ulmus, Carya, Liquidambar and Fagus, vary considerably in relative abundances, suggesting climate variability. The reflected climate shows an overall trend towards cooling or deterioration which is largely in agreement with global climate change during the Neogene.Comparisons of the pollen record with representative datasets from neighbouring areas, together with the appearance of the highly-evolved genus Artemisia, suggest that the Yongqing Formation and the lower part of the Daqingshan Formation are of Miocene age.