Quantitative assessment of terrigenous sediment flux to the deep basin has mainly been limited to the Cenozoic Era, given challenges with reconstruction of more ancient source to sink systems. Subsurface mapping in the northern Gulf of Mexico basin, where there is a robust database of wells and seismic data, allows estimation of sand-size grain volumes within 12 chronostratigraphically defined Late Mesozoic supersequences. Five subsurface depocentres with thicknesses of >400 m are identified, revealing a history of sediment routing via major fluvial axes (paleo rivers) southward from a mid-continent drainage divide. The interpreted paleo-rivers are further confirmed by compilation and synthesis of published and novel detrital zircon provenance data showing combinations of age peak subsets that vary considerably between depocentres. This study quantifies sediment volumes within each depocentre by inverting porosity over defined gross rock volumes derived from subsurface well | 1271 EAGE SNEDDEN et al.