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The Permian Taiyuan and Shanxi formations exposed in Shandong Province, eastern North China, contain abundant spores and pollen. In this study, a total of 42 genera and 146 species of spores and pollen from these Permian formations, native to northern China, are identified and related to the three epochs of the Permian Period (Cisuralian, Guadalupian, and Lopingian Epochs) as two assemblages: Assemblage Ithe Laevigatosporites-Granulatisporites assemblage, inferred as the Cisuralian (~298.9-272.9 Ma); and, Assemblage IIthe Gulisporites-Sinulatisporites assemblage, inferred as the Guadalupian (~272.9-259.1 Ma). Assemblage I represents growing ferns, whereas Assemblage II represents gymnosperms. The assemblage division and analysis indicated that the palaeoclimate of the study area during Early-Middle Permian time was dominated by warm and humid conditions, and later in the Middle Permian changed into moderately dry conditions.

Important geological events that influenced the global environment occurred during the mid‐Cretaceous period. Dramatically increasing temperatures not only triggered oceanic anoxic events (OAEs) but also led to the aridity of terrestrial environments in East Asia. This study provides evidence for the aridity of a terrestrial East Asian environment during the mid‐Cretaceous and provides an example of the influence of the Cretaceous greenhouse climate on a terrestrial lake system in correspondence with the OAE 1a event. Palaeosalinity indexes (B, B/Ga, Sr/Ba, and Couch's palaeosalinity) and palaeoclimate proxies (Sr/Cu, Rb/Sr, Al2O3/MgO, and clay mineral compositions) of shale and mudstone from the Laiyang Group of the Jiaolai Basin in Eastern China were analysed. The results demonstrate that the palaeoclimate in the Wawukuang Formation was relatively warm and humid but became extremely dry and hot in the Shuinan Formation during the OAE 1a event before becoming warm and humid again in the Longwangzhuang and Qugezhuang formations. As a result, the palaeosalinity of the Jiaolai Basin increased from 4% in the Wawukuang Formation to 30% in the Shuinan Formation before decreasing to 0.48% in the Longwangzhuang and Qugezhuang formations. The following conclusions are from combining the distributional characteristics of the saliferous strata and its palaeontology, the palaeogeographic background, and the aeolian sandstone in eastern China. (a) The East Asian continental margin was influenced by the Cretaceous greenhouse climate, which resulted in the salinization of the Jiaolai Basin. (b) The significant increase of the palaeosalinity in the Shuinan Formation was an effect of the OAE 1a event on the terrestrial lake system, which further suggests the OAE 1a event was global. (c) Influences of the hothouse climate on the continental lakes changed the palaeosalinity of the water bodies.

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