The palynological record from Coniacian to lower Campanian continental sequences in the Songliao Basin, northeastern China and its implications for palaeoclimate

摘要

A palynological record recovered from successions of Coniacian to early Campanian age (89.1-83.5 Ma) was obtained from the lacustrine sequences of the SR-I south core (SR-Is) in the Songliao Basin, northeastern China. The palynoflora is dominated by bisaccate gymnosperm pollen, followed by spores of pteridophytes, and just minor amounts of angiosperm pollen. Based on the relative abundance of the different spore and pollen taxa through the core, the succession was subdivided into three palynological assemblages. The results indicate two opposite trends for climate change, a minor warming trend (from 89.1 to 85.7 Ma) followed by a rapid cooling trend (85.7-83.5 Ma). The first warming trend reached its maximum at 85.7 Ma, which is inconsistent with results from the marine realm (which instead show a minor cooling trend based on several proxy records). However, the second cooling phase is consistent with global changes from various and abundant palaeoclimate proxies from marine deposits. We interpret the climatic changes within the studied interval (89.1-83.5 Ma) as a consequence of the shifting climate from a hot/super greenhouse to a temperate greenhouse. (C) 2015 Elsevier Ltd. All rights reserved.