Abstract It has been said that large rivers are the bloodlines of continents, and the Mississippi River system is the most prominent bloodline in North America. The Mississippi drainage stretches from the Rocky Mountains in the western USA to the Appalachian Cordillera in the east, and sediment from this vast area is then routed to the alluvial–deltaic plain of south Louisiana and the basin-floor fan in the deep Gulf of Mexico (GoM). Origins of the Mississippi system can be traced to the Late Cretaceous–Early Paleocene reorganization of North American drainage. However, integration of a continental-scale Mississippi drainage is a Late Neogene phenomenon, and sediment routing to the GoM has changed significantly over multiple timescales in response to a variety of large-scale natural forcing mechanisms and to human activities. This paper reviews large-scale change in drainage, sediment routing and sediment storage for the Mississippi system over timescales of 150 myr, where tectonic and geodynamic processes dominate, the last 150 kyr, where Milankovitch climate and sea-level changes dominate, and the 150 year period of the twentieth and twenty-first centuries when human activities have fundamentally altered the sediment routing and dispersal system.

Abstract U-Pb dating of detrital zircons in fluvial sandstones provides a method for reconstruction of drainage basin and sediment routing systems for ancient sedimentary basins. This paper summarizes a detrital-zircon record of Cenomanian paleodrainage and sediment routing for the Gulf of Mexico and U.S. midcontinent. Detrital zircon data from Cenomanian fluvial deposits of the Gulf of Mexico coastal plain (Tuscaloosa and Woodbine formations), the Central Plains (Dakota Group), and the Colorado Front Range (Dakota Formation) show the Appalachian-Ouachita orogen represented a continental divide between south-draining rivers that delivered sediment to the Gulf of Mexico, and west- and north-draining rivers that delivered sediment to the eastern margins of the Western Interior seaway. Moreover, Cenomanian fluvial deposits of the present-day Colorado Front Range were derived from the Western Cordillera, flowed generally west to east, and discharged to the western margin of the seaway. Western Cordillera-derived fluvial systems are distinctive because of the presence of Mesozoic-age zircons from the Cordilleran magmatic arc: the lack of arc zircons in Cenomanian fluvial deposits that dis-charged to the Gulf of Mexico indicates no connection to the Western Cordillera. Detrital zircon data facilitate reconstruction of contributing drainage area and sediment routing. From these data, the dominant system for the Cenomanian Gulf of Mexico was an ancestral Tennessee River (Tuscaloosa Formation), which flowed axially through the Appalachians, had an estimated channel length of 1200-1600 km, and discharged sediment to the east-central Gulf of Mexico. Smaller rivers drained the Ouachita Mountains of Arkansas and Oklahoma (Woodbine Formation), had length scales of <300 km, and entered the Gulf through the East Texas Basin. From empirical scaling relationships between drainage-basin length and the length of basin-floor fans, these results predict significant basin-floor fans related to the paleo-Tennessee River system and very small fans from the east Texas fluvial systems. This predictive model is consistent with mapped deep-water systems, as the largest fan system was derived from rivers that entered the Gulf of Mexico through the southern Mississippi embayment.

Abstract Fluvial systems possess a range of scaling relationships that reflect drainage-basin controls on water and sediment flux. Quaternary channel-belt thickness (as controlled by bank-full water discharge) has been documented as a reliable first-order proxy for drainage basin size if climatic regimes are independently constrained. In hydrocarbon exploration and production, scaling relationships for fluvial deposits can be utilized to constrain drainage basin size with implications for sequence-stratigraphic interpretations. This study documents the scales of channel belts within Cenomanian fluvial successions from the Gulf of Mexico. Data on single-story channel-belt scales were compiled from well logs and utilized to constrain contributing catchment areas of fluvial systems. The data indicate that the Cenomanian fluvial systems were significantly smaller than the Cenozoic fluvial systems, which can be related to drainage basin reorganization. These scaling relationships can be validated by regional paleogeographic maps and provide additional insight into the variability of sediment routing systems through time.