Late Pliocene Palynoflora From Songliao Basin and Its Palaeoenvironmental Significance

Abstract

A systematic study of spores and pollen grains from the Pliocene Taikang Formation in the Longwantong Sag provides comprehensive insights into paleovegetation and paleoclimate changes, offering robust evidence for the paleoenvironmental evolution of the Songliao Basin since the Pliocene. Three distinct sporopollen assemblages were identified: (1) Artemisiaepollenites-Chenopodipollis-Pinuspollenites, (2) Pinuspollenites–Piceaepollenites–Quercoidites, and (3) Artemisiaepollenites-Chenopodipollis-Pinuspollenites-Polypodiaceaesporites. Based on the geological ranges of key taxa and comparisons with contemporaneous sporopollen assemblages from other regions, these deposits are confidently dated to the Late Pliocene. Our reconstruction reveals that the Longwantong area underwent three major vegetation transitions during the Late Pliocene from sparse forest-steppe to coniferous forest and back to sparse forest-steppe, corresponding to climatic fluctuations between cold/dry, cold/wet, and cold/dry conditions. The overall dry and cold climate change is a response to the global climate after 2.8 Ma.