Was climatic cooling during the earliest Carboniferous driven by expansion of seed plants?

Abstract

The expansion of land plants is considered to have played a key role in triggering the Late Paleozoic Ice Age (LPIA), but evidence linking climatic events to terrestrial floral changes is limited. Here, we generated bulk carbonate δ13C, conodont δ18O and 87Sr/86Sr profiles from the lowermost Carboniferous of South China and Vietnam in order to investigate their relationship to contemporaneous land plant evolution. Climatic cooling in the mid-Tournaisian coincided with large perturbations to the global carbon cycle and continental weathering regimes as well as with a major diversification episode among seed plants. These relationships are consistent with terrestrial floral changes triggering intensified weathering of basalts (i.e., lower 87Sr/86Sr), enhanced marine productivity (i.e., higher δ13Ccarb), and reduced atmospheric pCO2 and attendant global cooling (i.e., higher conodont δ18O). The results of our study suggest that expansion of terrestrial floras was a key driver of Early Carboniferous climate change.