--> Abstract: Comparing Belly River and Sunburst Channels with Today's Meandering Milk River, Southern Alberta, by Godfried Wasser; #90039 (2005)

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Comparing Belly River and Sunburst Channels with Today's Meandering Milk River, Southern Alberta

Godfried Wasser
Canadian Natural Resources Ltd, Calgary, AB

This core display attempts to apply the old geological adage ‘the present is the key to the past'. Cores, interpreted as meandering river deposits from the Belly River Formation in central Alberta comprise one (1) to three stacked fining upward successions, each with an erosional base, trough cross bedded medium to coarse grained sandstone and, in places, small scale ripple laminated fine grained sandstone at the top.

Cores from the Sunburst Formation in the Horsefly pool (southern Alberta) have a much larger number of fining upwards successions comprising medium to coarse grained sandstones with trough cross bedding or tabular sets. Most successions are thinner than those of the Belly River, however younger successions tend to be thicker than the ones below and grade upward into very fine grained ripple laminated sandstones.

To understand why one might interpret the deposits of both formations as meandering river deposits, we look at today's Milk River in Southern Alberta. This river is a meandering system with an inherited valley that due to recent uplift of our foreland basin cannibalizes its own deposits.

The Milk River has a meander belt of approximately 800m wide; individual channels are approximately 60 to 80 meters wide with a depth of 6 to 8 meters. The river's dimensions follow the traditional ‘channel depth-channel width-belt width' rules. Based on these dimension rules, the Belly River and Sunburst channel deposits could have been formed in systems comparable to Milk River dimensions.

Milk River deposits will probably not be preserved due to basin-uplift. Preservation of the Belly River's relative thick, homogeneous, meandering deposits would require the opposite - rapid basin subsidence.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005