Climate characteristics of the eastern Mongolian Plateau, China during the early Early Cretaceous (145-132 Ma):Palynological evidence from the Tongbomiao Formation in Well Hong-6, Hailar Basin
Yan Zhang Yun-fei Xue Chun-yang Bu Ti Li Xin Zhang Yu-dong Jin Yue-wu Sun
中国地质（英文）2022，Vol.5Issue(3)：439-456,18.
中国地质（英文）2022，Vol.5Issue(3)：439-456,18.DOI:10.31035/cg2022016
Climate characteristics of the eastern Mongolian Plateau, China during the early Early Cretaceous (145-132 Ma):Palynological evidence from the Tongbomiao Formation in Well Hong-6, Hailar Basin
Climate characteristics of the eastern Mongolian Plateau, China during the early Early Cretaceous (145?132 Ma):Palynological evidence from the Tongbomiao Formation in Well Hong-6, Hailar Basin
摘要
Abstract
This study identified two palynological assemblages, namely Bayanhuasporites-Cycadopites-Protoconiferus and Cicatricosisporites-Cedripites-Perinopollenites, in the Tongbomiao Formation in the Hongqi Sag in the Hailar Basin, Inner Mongolia, China for the first time. The former is distributed in the lower part of the Tongbomiao Formation and is characterized by abundant gymnosperm pollen and diverse fern spores. Among them, the gymnosperm pollen is dominated by Paleoconifer (4.98％–31.62％) and Cycadopite (8.55％–25.23％) pollen grains and also includes other pollen grains such as Classopollis, Parcisporites, Erlianpollis, Callialasporites, and Jiaohepollis. The fern spores in the former palynological assemblage contain Bayanhuasporite (0–8.96％), Granulatisporites (0.93％–6.97％), and some important Cretaceous genera, such as Cicatricosisporites, Concavissimisporites, Densoisporites, Hsuisporites, Foraminisporis, and Leptolepidites. The Cicatricosisporites-Cedripites-Perinopollenites palynological assemblage is distributed in the upper part of the Tongbomiao Formation. Gymnosperm (77.30％), Pinaceae (31.9％), and Paleoconiferus (19.02％) pollen predominate this palynological assemblage, and Quadraeculina, Erlianpollis, and Jiaohepollis pollen are also common in this assemblage. The fern spores in this palynological assemblage include abundant Cicatricosisporites (4.29％). Besides, Concavissimisporites, Aequitriradites, and Leptolepidites are also common in this palynological assemblage. No angiosperm pollen has been found in both palynological assemblages. The identification of both palynological assemblages provides important evidence for the biostratigraphic correlation between the Hailar Basin and its adjacent areas. It also enables the reconstructions of the Berriasian-Valanginian (Early Cretaceous) vegetation and the paleoclimate on the eastern Mongolian Plateau during 141–132 Ma. The vegetation reconstructed on the palynological data of the represented by Hailar Basin in eastern Mongolian Plateau (141.6–141.4 Ma), form conifer forest or conifer broad-leaved mixed forest to conifer forest with shrubs and grassland, the climate belongs to warm temperate and warm-subtropicalt, the highest temperature is estimated to reach 35–38℃. Form 132.3 Ma, the vegetation type is conifer forest, and its paleoclimate is sub-humid warm temperate, the highest temperature is estimated to reach 24–29℃.关键词
Tongbomiao Formation/Palynological Assemblages/Gymnosperm/Berriasian-Valanginian/Palaeovegetation/Palaeoclimate/Hailar Basin/Mongolian Plateau/ChinaKey words
Tongbomiao Formation/Palynological Assemblages/Gymnosperm/Berriasian-Valanginian/Palaeovegetation/Palaeoclimate/Hailar Basin/Mongolian Plateau/China引用本文复制引用
Yan Zhang,Yun-fei Xue,Chun-yang Bu,Ti Li,Xin Zhang,Yu-dong Jin,Yue-wu Sun..Climate characteristics of the eastern Mongolian Plateau, China during the early Early Cretaceous (145-132 Ma):Palynological evidence from the Tongbomiao Formation in Well Hong-6, Hailar Basin[J].中国地质（英文）,2022,5(3):439-456,18.基金项目
The authors would like to extend their sincere gratitude to the anonymous reviewers and editors for their constructive suggestions on this manuscript.This work was completed in the palynological laboratory of the Exploration and Development Research Institute of Daqing Oilfield Company Limited and was financially supported by the National Natural Science Foundation of China(41972012 and 31270277).The authors'thanks also go to Prof.Shu-qin Zhang from the Research Center of Paleontology and Stratigraphy,Jilin University for samples analysis and to senior engineer Xu Yang from the Exploration and Development Research Institute of Daqing Oilfield Company Limited for providing the division scheme of tectonic units in the Hongqi Sag. （41972012 and 31270277）
