AAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
Controls on Fluvial Channel Belt Architecture from the Cretaceous Blackhawk Formation of Eastern Utah
(1) UniCIPR, University of Bergen, Bergen, Norway.
To investigate controls on large scale fluvial sandbody architecture, two very large virtual outcrops (> 10 km each) were created from the non-marine part of the Blackhawk Formation in eastern Utah. Data were collected using helicopter-mounted, oblique lidar (i.e. laser-based) combined with a very high resolution digital camera. Such a system allows large volumes of accurate, geospatially constrained information to be rapidly collected from outcrops that are otherwise inaccessible.
The non-marine part of the Blackhawk Formation was deposited on a Cretaceous coastal plain during an overall regression of the Western Interior Seaway. The two studied intervals come from either side of the San Rafael Swell. The Wasatch Plateau section is >250 m thick and was deposited in the fore-deep c. 60 km from the contemporaneous Sevier thrust front. The second section is from the Beckwith Plateau (Book Cliffs), 70 km further east (down dip) and is 40-50 m thick.
Dimensions and stratigraphic position relative to a series of datums have been measured for several hundred individual fluvial sandbodies in order to empirically investigate lateral and vertical controls on large scale geometry and stacking patterns. Analysis of the data shows that systematic changes exist both vertically and laterally over very large distances. Channel sizes become smaller and more ordered down depositional dip. Furthermore there seems to be no significant change in barform geometry and scale at the Blackhawk to Castlegate transition, as described by previous workers. The results of this study can be used as robust input data for reservoir modeling.