A new processing method for the pollen samples from Palaeogene red beds in the Liguanqiao Basin, Hubei Province, and Pleistocene loess from the Chinese Loess Plateau

Over the past decade, palynoflora investigation of Palaeogene and Neogene red beds and Pleistocene loess has been the focus of an increasing number of studies. Pollen extraction from sediments is a prerequisite for palynoflora investigation. This study explored a new pollen processing method and successfully extracted a large number of pollen grains from the Palaeogene red beds in the Liguanqiao Basin, Hubei Province and the Pleistocene loess from the southern Chinese Loess Plateau. There are several key steps in this new method. (1) Samples from arid to semi-arid regions are usually well cemented and should be gently crushed and sieved with 30-mesh screen for pollen analysis to maximize the number of pollen grains recovered from sediments. (2) In order to remove organic matter most effectively, samples should be heated until just boiling in ∼3% NaOH solution for not more than 5 min (3) The residue after acid–alkali treatment should be dried at 85 °C for 7–9 h to ensure that density of the heavy liquid is not diluted during the next step. (4) KI heavy liquid, with a density of 1.74–1.76, should be used to concentrate the pollen. (5) Sieving with a 7-μm stainless steel mesh resulted in the loss of few pollen grains. In contrast, sieving with a 10-μm nylon mesh resulted in loss of many small pollen grains. Importantly, this study extended the first appearance of Artemisia in China back to the Late Palaeocene, and is significant for vegetation reconstruction in the arid to semi-arid regions during the Cenozoic Era.