--> Abstract: Salt Tectonic Controls on Fluvio-Lacustrine Stratigraphy: From Outcrop to Subsurface, by Wendy Matthews, Gary Hampson, Bruce Trudgill, John Underhill, and Lutz Seiffert; #90039 (2005)

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Salt Tectonic Controls on Fluvio-Lacustrine Stratigraphy: From Outcrop to Subsurface

Wendy Matthews1, Gary Hampson1, Bruce Trudgill2, John Underhill3, and Lutz Seiffert4
1 Imperial College London, London, United Kingdom
2 Colorado School of Mines, Golden, CO
3 University of Edinburgh, Edinburgh, United Kingdom
4 Total Explortaion UK PLC, Aberdeen, United Kingdom

Salt-sediment interaction occurs at a range of scales with a variety of different manifestations including, structural controls in the subsurface, geomorphological processes at the surface, formation-scale thickness changes, and intra-formational facies variability. An understanding of this interaction is critical to the evaluation and prediction of depositional facies in both outcrop- and subsurface-based studies. Large-scale stratal geometries and thickness changes resulting from salt movement are often apparent on 3D seismic data, but to date there are few predictive models for facies architecture at sub-seismic, reservoir scale.

This study uses a high-quality outcrop dataset of fluvio-lacustrine strata in an exhumed salt basin (late Triassic Chinle Formation, Paradox Basin, Utah) as an analogue for improved understanding of a subsurface dataset of similar structural and sedimentological setting (Triassic Skagerrak Formation, Central North Sea, UK). Salt-sediment interaction in the Chinle Formation is expressed by localised (km-scale) stratigraphic thickness variations, angular stratal relationships and changes in facies architecture. Based on these criteria, there is evidence for salt-sediment interaction across a range of syn-depositional salt structures, including an anticline above a buried salt pillow (Cane Creek anticline), a salt wall exposed at surface (Moab Valley salt wall), and a salt-withdrawal mini-basin (Big Bend mini-basin). Stratigraphy and facies architecture across these structures reflect the following controls: regional subsidence, localised differential accommodation space, and localised palaeogeomorphology. Both localised controls were driven by syn-depositional salt movement. The results of this outcrop study are being applied to predicting stratigraphic relationships, facies architecture and reservoir distribution in the subsurface.

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