--> Abstract: Facies and Lithology Distribution Patterns Derived from Evolving Seismic Geomorphologies Within a Seismic Stratigraphically Well Constrained Submarine Fan Complex, by Frode Hadler-Jacobsen, Michael H. Gardner, and James M. Borer; #90039 (2005)

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Facies and Lithology Distribution Patterns Derived from Evolving Seismic Geomorphologies Within a Seismic Stratigraphically Well Constrained Submarine Fan Complex

Frode Hadler-Jacobsen1, Michael H. Gardner2, and James M. Borer2
1 Statoil ASA, Golden, CO
2 Colorado School of Mines, Golden, CO

Spatial and temporal seismic stratigraphic trends document the deepwater evolution in a small window (20-x30 km area) across the South Atlantic Margin. Integration of seismic geomorphological (map) and architectural (cross-sectional) analysis documents changes in confined (channel) and unconfined (sheet) elements within a fourfold stratigraphic hierarchy of fan cycles (2nd order through 5th order). With no direct borehole calibration data in the studied sub-basin, lithology prediction is based on (1) differential compaction features indicative of lithogy contrast, (2) indirect calibration to wells outside the South Atlantic Margin sub-basin of interest, and (3) analogue comparison to Brushy Canyon 3D outcrop models documenting detailed lithology distributions within a high-resolution stratigraphic hierarchy.

Three significant shifts in channel- and sheet-orientation and pattern are related to 2nd order tectonostratigraphic cycles recording the (c. 50my) basin margin evolution. 3rd order cycles show sets of sheet-channel couplets distributed in distinctly compensation patterns. 4th order cycles typically represent sheet-channel couplets repeated in predictable patterns of increasing channel-flank proportions and decreasing sheet proportion up stratigraphy. Individual (5th order) fan cycles, typically expressed as a single seismic loop, show a clear and predictable relationship to evolving seabed topography. Evolving seabed topography and gradients, related to the effect of basin margin evolution, produces predictable sheet and channel distributions within a fan cycle. Changes in channel orientation-, avulsion-, compensation-patterns and the position of channel mouths can be related to gradient changes within and between stratigraphic cycles.

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