Lacustrine carbon sink: A hidden driver of the Late Cretaceous Cooling Event.

Lacustrine systems since the Mesozoic have sequestered large quantities of organic carbon, which may have important value for global climate cooling, but there is still a lack of geological evidence of this sequestration. Taking the Songliao Basin in China as a case study, we elucidate the important function of lacustrine basins as sinks of a large amount of organic carbon, particularly when the contemporaneous marine sediments were poor sinks of organic carbon. Volcanic activities and orbital forcing were likely key factors influencing the water transportation between the land and oceans, as well as the alternating burial of organic carbon in the oceans and land. Microorganisms related to methane metabolism may have been highly involved in the mineralization and sequestration of lacustrine organic carbon. This study provides new insights into the coupled carbon-water cycle between the land and oceans and the influence of this process on global climate evolution.