Vegetation and climate history during the Mammoth subchron from high-resolution pollen records in Yinchuan Basin, northwestern China

The Mammoth subchron was a significant geomagnetic reversed polarity event within the Gauss normal chron interval; however, the availability of high-resolution climate change records during this period is limited. We reconstructed the vegetation and climate history in the period using high-resolution pollen records from core PL02 (depths from 705.7 to 678.9 m) from the Yinchuan Basin, northwestern China. The results showed that the vegetation in the Yinchuan Basin was dominantly desert steppe during this period and that a gradual increase in arid conditions was superimposed by warm and humid and cold and dry conditions, but the climate was slightly wetter than that during the Quaternary. From 3.337 to 3.313 Ma, the study area climate was relatively warm and humid, and an especially warm and humid climate event from similar to 3.322 to 3.313 Ma was reflected by the highest pollen concentrations of trees, shrubs and herbs and a low percentage of herbs. From 3.313 to 3.287 Ma, the percentage of herbs and xerophytic shrubs (such as Chenopodiaceae, Artemisia and Nitraria) increased gradually, reflecting a relatively cold and dry climate. From 3.287 to 3.241 Ma, the herb taxa percentage decreased, and the climate became wetter relative to the previous stage. However, after similar to 3.241 Ma, the xerophytic plant abundance increased significantly, and the proportion of arboreal plants reached a minimum, indicating that the climate in the Yinchuan Basin became much drier than before. Moreover, the results suggested that the vegetation and climate change in the Yinchuan Basin might be related to global change. (C) 2020 Elsevier B.V. All rights reserved.