Distinguishing allogenic and autogenic processes on the distribution and patterns of channel belts of fluvial systems is challenging because both can control avulsions across a range of time scales and because of incomplete preservation. In this paper, Flood and Hampson present a quantitative analysis of the distribution of channelized fluvial sandbodies within the widely studied Blackhawk Formation of the Wasatch Plateau, central Utah. The results indicate that: 1) spatial patterns of sandbody distribution can be attributed to avulsion of deltaic distributary channels in locations downstream of long-lived avulsion nodes in the lower part of the Blackhawk Formation, or by compensational stacking of sandbodies in the upper part of the Blackhawk Formation, and 2) tectonic subsidence rate varied markedly during deposition (c. 80-700 m/Myr), but any potential variation in its relationship to avulsion frequency had little influence on avulsion style. This study demonstrates the importance of collecting large outcrop datasets, which enable quantitative characterization of sandbody distributions and related stratigraphic architectures using spatial statistical methods.
Quantitative analysis of the dimensions and distribution of channelized fluvial sandbodies within a large outcrop dataset: Upper Cretaceous Blackhawk Formation, Wasatch Plateau, central Utah, U.S.A. by Yvette S. Flood and Gary J. Hampson