Hyperpycnal Rivers and Prodeltaic Shelves in the Cretaceous Seaway of North America

摘要

Despite the historical assumption that the bulk of marine "shelf" mud is deposited by gradual fallout from suspension in quiet water, recent studies of modern muddy shelves and their associated rivers show that they are dominated by hyperpycnal fluid mud. This has not been widely applied to the interpretation of ancient sedimentary fluvio-deltaic systems, such as dominate the mud-rich Cretaceous Western Interior Seaway of North America. We analyze two such systems, the Turonian Ferron Sandstone Member of the Mancos Shale Formation, in Utah, and the Cenomanian Dunvegan Formation in Alberta. Paleodischarge estimates of trunk rivers show that they fall within the predicted limits of rivers that are capable of generating hyperpycnal plumes.