AAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
Evidence for Along Strike Variation in Structural Style, Geometry and Its Possible Causes: A Case Study Along the UK Flank of the Faeroe-Shetland Basin (North Atlantic Margin)
(1) Earth Sciences, Royal Holloway, Univeristy of London, London, United Kingdom.
(2) Subsurface Department, GDFSUEZ Exploration and Production United Kingdom, London, United Kingdom.
(3) New Ventures, GDFSUEZ Exploration and Production United Kingdom, London, United Kingdom.
Newly reprocessed seismic data across the Faeroe-Shetland Basin, has given improved data quality and has enabled the identification of a combination of extension and inversion systems resulting in different geometries observed along the UK flank of the basin.
The stratigraphic succession simply comprise of sand and shale alternations with limestone bands from Devonian to Late Cretaceous and sand, shale, tuff, lava flow with associated dykes and sills dorminating Palaelocene to recent.
In the southern part, the structural style is characterized by extension with intence dyke and sill emplacement. The resulting geometry is roll-over anticline, inflation anticline and fault types are polygonal faults and listric extensional faults. In the central part, in the Muckle basin, the early extensional regime is overprinted with mild contraction during the Late Cretaceous. This contraction resulted in localized uplift and buckling which caused erosion of Jurassic/Early Cretaceous sediment and deposition of mass transport deposit down slope. Polygonal faults are formed in the deeper sequence of the basin during the Cenozoic. In the northern part, the structural style shows intense contraction that resulted in more significant inversion with pronounced harpoon structures dominant in the Cretaceous sections, dykes and sill emplacement and imbricate faults with the mass transport deposit during the Cenozoic.
This complexity is interpreted to be caused by a combination of: (i) Segmentation of the basins due to its evolution (from intra-cratonic pull-apart basin) (ii) NW Europe regional plate movement, associated with the opening of the Atlantic (iii) Emplacement of intrusive and extrusive volcanism, dykes and sills in the Paleogene (iv) Boundary fault movement, oblique extension and a possible transfer fault movement causing transtensional contraction and buckling especially in the Muckle sub basin (v) Sudden subsidence, dewatering and gravitation loading /sliding resulting in sediment progradation and polygonal faulting in deeper parts of the basin.
The varying influence of these factors may account for the distribution, complexity and distinct structural style and geometries along the UK flank of the Faeroe-Shetland Basin. An understanding of these factors is critical for exploration success with the Faeroe-Shetland Basin.