Mike J. Young1,
Rob L. Gawthorpe2,
John R. Underhill4
(1) The University of Manchester, Manchester, United Kingdom
(2) University of Manchester, Manchester, United Kingdom
(3) Saga Petroleum, N-1301 Sandvika, Norway
(4) Edinburgh University, Edinburgh, United Kingdom
Abstract: The stratigraphic response to extensional fault growth and linkage
Conceptual models predict that fault linkage exerts a strong control on the development of syn-rift successions. In particular, along-strike variations in stratal thickness, architecture and stacking patterns should be influenced by the growth, interaction and linkage of fault segments. These issues are addressed through an integrated study of syn-rift sediments using high-quality 3D seismic data (Northern North Sea) and detailed outcrop studies (Gulf of Suez).
The Murchison fault zone in the North Sea is a NE-SW to NW-SE trending planar, down to the east, normal fault zone 30 km in length. Detailed analysis of 3D seismic data delineates several syn-rift depocentres (up to 4 km in length and 2 km in width) adjacent to the fault zone, suggesting that the fault initially consisted of a series of unlinked segments. As progressive fault growth occurred, the segments linked to form two larger fault segments separated by a relay ramp. The ramp was subsequently breached to form the current structural configuration. The breaching event is also reflected in the syn-rift stratigraphy.
Syn-rift clastics from the Hammam Faraun and El Qaa fault blocks of the Suez Rift preserve similar relationships between fault growth and stratigraphic development. The early syn-rift is localised in discrete hanging-wall sub-basins, with the later syn-rift having a wider distribution. Lateral variations in stratal architecture and stacking patterns are particularly evident, being controlled by along-strike variations in fault displacement and sediment supply. The results of this study have implications for the spatial and temporal variation of subtle hanging-wall plays.
AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana