Monday, April 10, 2017

Highlights: Alluvial Sand Bodies Can Cluster

Alluvial architecture includes describing stacking patterns, spatial density of fluvial channel-belt sandstone bodies, and connectivity, aspects shaped by influences of autogenic and allogenic processes. This study by Benhallam et al. attempts to understand the relative roles of allogenic and autogenic factors on the fluvial John Henry Member of the Straight Cliffs Formation (Cretaceous) of the southwestern Kaiparowits Plateau of Utah. To attempt to discriminate between local and regional controls, this study uses a suite of spatial algorithms to quantify and statistically discriminate clustered, uniform, or random channel-belt bodies in several outcrops. By comparison with predictions from various experimental and numerical models of alluvial architecture, the existence of different patterns at different spatial scales implicates avulsion reoccupation at the small scale, and avulsion-driven compensational stacking at a larger scale. This study suggests that specific types of channel stacking patterns provide insights into the underlying controls and depositional processes, such as compensational stacking and avulsion reoccupation.

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