Source-to-Sink Sediment Routing and Environmental Signal Propagation in an Uplifted Foreland Basin, Lower Cretaceous Alberta Basin, Canada

Abstract

Sediment dispersal in foreland basins is mainly controlled by tectonically induced subsidence and sediment supply. As such, many foreland basins exhibit a predictable drainage pattern where basin-axial channel systems are intersected by transverse drainages that emanate from uplifting orogens. During phases of relative tectonic quiescence, however, the foreland can isostatically rebound, complicating basin configuration, sediment routing, and propagation of environmental signals (e.g., uplift).

The Alberta Foreland Basin of Western Canada consists of a 4 km thick wedge of sediment that records tectonic activity from 200-50 Ma. Basin initiation took place in the Jurassic with formation of an asymmetric foredeep that filled with detritus from the emerging Cordillera. Jurassic foreland strata indicates a typical foreland sediment dispersal pattern. During tectonic quiescence in the Early Cretaceous, the foreland was uplifted and a basin-wide unconformity formed, exposing increasingly older Mesozoic-Paleozoic sedimentary units eastward towards the craton. Aptian lower Mannville Group units directly accumulated on this unconformity. Differential erosion of subcropping units created a partitioned basin, and capture of three distinct basin-axial channel systems marked by distinct U-Pb detrital zircon age distributions. The axial drainage next to the orogen derived sediment mainly via recycling of the orogenic wedge, with input from magmatic rocks of the Cordillera. Cratonward, dissolution of subcropping salt led to topography that captured a continental-scale river system with headwaters in the south and eastern United States. During the Albian, a thick asymmetric wedge accumulated in the foreland basin, indicating that sediment dispersal was once again controlled by elevated basin subsidence and sediment supply.

The distribution of accommodation and sediment routing trends during periods of uplift and erosion in a basin are difficult to predict. Environmental controls can affect the development of topography on erosional surfaces and exert a greater influence on sediment dispersal. In the Alberta Basin, foreland uplift controlled deposition of the Mannville Group, which includes vast hydrocarbon resources (e.g., Athabasca Oil Sands). A database including outcrops, 1000s of wellbores, and expansive detrital zircon analyses (N = 40; n = 5652) is used to demonstrate the impact of an uplift-induced partitioned foreland on sediment routing and reservoir distribution.

AAPG Datapages/Search and Discovery Article #90323 ©2018 AAPG Annual Convention and Exhibition, Salt Lake City, Utah, May 20-23, 2018