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Tectonic Controls from Turbidite Channel Complexes along Deepwater Margins Revealed Using Isoproportional Slicing, Spectral Decomposition and Multi-Attribute Blending

Gawthorpe, Robert 1; Leppard, Chris 2
1 School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Manchester, United Kingdom.
2 StatoilHydro AS, Bergen, Norway.

Attribute analysis of three-dimensional seismic volumes has allowed detailed imaging of submarine channels on deepwater margins and provides a wealth of information on their geometry, variability and evolution. In tectonically complex areas, analysis of the regional linkages between growing faults and folds and deepwater depositional systems is more problematic and often requires detailed mapping of closely spaced horizons in order to visualise the interplay of evolving slope structures and deposition. We present examples from Atlantic and Gulf of Mexico margins to illustrate the combined use of isoproportional slicing, advanced spectral decomposition and muliti-attribute blending techniques to provide a workflow for relatively rapid analysis of deep marine depositional elements and their temporal and spatial response to tectonic forcing.

Deepwater depositional elements include a mixture of sinuous and straight isolated channels, channel complexes, channel levee systems, frontal splays and mass transport complexes that were deposited during growth of an array of salt-cored folds and associated growth faults. The evolving fault/fold arrays have a major control on the scale, geometry, location and stacking patterns of these depositional systems at local (individual structure) to regional (fault/fold array) scales. Sediment transport pathways become fixed by early formed structures high on the slope leading to long-lived, major sediment fairways that are 'pinned' during subsequent fold and fault growth, interaction and linkage lower on the slope. The geometry and variability of channel complexes also responds to the evolution of individual structures. During early stages of fold growth channels tend to be simple and isolated, and are orientated perpendicular to the regional slope. However, as folds grow and interact, the channels increase in sinuosity and their cross-sectional and long-profile geometry becomes progressively more variable and complex as slope roughness increases. As a result, channel orientations become increasingly complex with local deviations parallel to fold axes. Amplification of folds also leads to oversteepening and slope failure resulting in development of mass transport complexes that may dam entry or exit points between mini-basin depocentres.

 

AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009