Palynological record of the Cretaceous ZKD14 core (Songliao Basin, Northeast China) and its paleoclimatic significance

Abstract

To better understand the vegetation and possible paleoclimate change, we recovered a palynological record obtained from the ZKD14 core covering from the Sifangtai and Mingshui Formations in the northern Songliao Basin, northeastern China. Based on the abundance and variations in determined palynomorphs, two palynological assemblages can be distinguished, including Schizaeoisporites-bisaccate-Tricolporopollenites and Taxodiaceaepollenites-bisaccate-Tricolporopollenites. These palynological assemblages are assigned to the late Campanian-Maastrichtian stage based on the geological range of some important elements and the correlation with relevant assemblages of other areas. In this paper, we applied a sporopollen-climate transforming methodology, which uses the percentage of xerophytic and thermophilic taxa to indicate stratigraphic trends of humidity and temperature, respectively. Then two vegetation and paleoclimate phases were reconstructed based on the ecological habits of the parent plant, as well as the abundance variation in xerophytic and thermophilic taxa: (i) The vegetation type was interpreted to reflect a mixed conifer forest with varying pteridophytes landscape, presenting a hot and arid subtropic climate during the Sifangtai to lower part of member 2 of the Mingshui Formations. (ii) The vegetation type was characterized by a conifer-dominant landscape. Accordingly, the climate turned more humid and colder during the upper part of member 2 of the Mingshui Formation. The global cooling event (Campanian-Maastrichtian Boundary Event: CMBE) which occurred between 72.0-70.0 Ma appears to have an important influence on the climatic condition of Songliao Basin.

Petrography and geochemistry of Late Cretaceous clastic rocks in the northern Songliao Basin, north‐eastern China: Implications for provenance and weathering

“…Metamorphic lithic fragments are abundant in the detritus, generated by physical weathering processes such as disaggregation and comminution (Figure 3d), resulting in relatively low CIA values. The arid climate is also consistent with palynological data, which are obtained from the Sifangtai to Mingshui formations sediments and have higher contents in drought‐tolerant plants (Huang et al, 1999; Xu et al, 2020).…”

Late Cretaceous stratigraphic division in the northwestern Songliao Basin, Northeast China: Evidence from palaeontology and palaeomagnetism

“…Its representative species, L. giganteus , is also the characteristic pollen of the Nenjiang Formation in the Songliao Basin and the Zaoyang Formation in the Jinmen Basin (Gao et al, 1999; Li, Xi, et al, 2011). Gothanipollis plicus was commonly observed in the Nenjiang, Sifangtai, and Mingshui formations of the Songliao Basin (HBGM, 1993; Xu et al, 2020). Granwellia was another ubiquitous Late Cretaceous species worldwide (Gao et al, 1999).…”