The first palynological records from the Lower Cretaceous of the northern Sichuan Basin, China: Palynostratigraphical and paleoenvironmental significance

Majority of the aeolian deposits that are widely distributed throughout the low-latitudes during the Cretaceous have been considered to be the result of downdraft influence controlled by the subtropical high-pressure belt. However, a lack of relevant fossil material has hindered both the chronostratigraphic framework of these deposits and the reconstruction of their corresponding palaeoenvironments. This study presents detailed palynological records from two drillcores through the Lower Cretaceous Canxi and Bailong formations in the Sichuan Basin, Southwest China. Classopollis pollen, followed by the bisaccate conifer pollen, together with other rare types of palynomorph dominate the palynological assemblages that are recorded within. Some age-diagnostic palynomorphs, especially Dicheiropollis, indicate an age of Valanginian to Hauterivian for the Cangxi and Bailong formations. Classopollis-dominated palynoflora indicate an extremely dry climate for this part of the history of the Sichuan Basin region. In addition, the occurrence of Dicheiropollis indicates that the Sichuan Basin should belong to the Dicheiropollis Province that surrounds the Tethys Ocean, which implies that the Tethys Ocean may have exhibited a stronger climatic impact on the Sichuan Basin regions as compared to that exhibited by the Pacific Ocean.