SEDIMENT PROVENANCE AND DISPERSAL DURING FORELAND BASIN UPLIFT: LOWER CRETACEOUS MANNVILLE GROUP, ALBERTA BASIN, CANADA

Sediment distribution in foreland basins is largely controlled by variations in tectonically induced subsidence and sediment supply. Foreland basin drainage patterns commonly comprise evidence for basin axial channel systems intersected by transverse drainages that emanate from the adjacent orogenic belt. However, during periods of relative tectonic quiescence, a foreland can isostatically rebound; erosion during this period can reconfigure basin topography and complicate sediment dispersal. To add insight into sediment distribution during periods of relative tectonic quiescence, we analyze outcrop and well log data, as well as U-Pb detrital zircon ages (N = 26; n = 4963) from the Lower Cretaceous Mannville Group of the Alberta Basin, Canada. We use these data to hone the stratigraphic framework for the basin fill, examine sediment provenance, and investigate controls on sediment dispersal.

The Alberta Foreland Basin consists of a 4 km thick siliciclastic succession that records the tectonic evolution of western Canada from 200 – 50 Ma. Basin initiation took place in the Jurassic with the evolution of an asymmetric basin that derived sediment from the emerging Cordillera. Northward basin axial sediment transport was prevalent during this time. In the Early Cretaceous, the foreland was uplifted and an angular unconformity formed across the basin. Differential erosion of units exposed on the surface resulted in a topographically segmented basin characterized by formation of three distinct basin-axially oriented drainages; each is demarcated by deposits with distinct U-Pb age signatures. The drainage adjacent to the orogen primarily captured recycled sediment and detritus from magmatic rocks of the Cordilleran hinterland. Cratonward, dissolution of subcropping salt and erosion of recessive units led to the capture of a continental-scale river system with headwaters in the south and eastern United States. The results of the study demonstrate the effectiveness of denudation-controlled topography for segmenting sediment-routing systems within foreland basins. This has important implications for explaining the distribution of hydrocarbon resources in the Alberta Basin, as well as the interpretation of provenance data in other foreland settings globally.