Middle Eocene terrestrial paleoweathering and climate evolution in the midlatitude Bohai Bay Basin of Eastern China

The middle Eocene is a key time period for understanding Cenozoic cooling of the global climate. In eastern Asia, this time period was marked by deposition of extensive mudstones, shales and interbedded siltstones, especially in the midlatitude Bohai Bay Basin. Still, midlatitude terrestrial records of climate evolution during the middle Eocene are rare. Here, we analyze a continuous, high-resolution record of this period using samples of the shales in the fourth submember of the third member from the mid-Eocene Shahejie Formation (MES shales) in the Bohai Bay Basin using major-element and wavelet analysis. We use this information to derive insights into terrestrial paleoweathering and paleoclimatic evolution during the mid-Eocene in this midlatitude region. As a result of element mobility during continental weathering, the MES shales are more enriched in Ca and depleted in Na compared to average upper continental crust (UCC). The MES shales experienced moderate paleoweathering with lim...