--> ABSTRACT: Slope Turbidite Reservoir Development along a Tectonically Active Margin (Part II) — An Up-System Perspective from the Upper Cretaceous, Offshore Norway, by Sømme, Tor O.; Jackson, Christopher A.; #90142 (2012)

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Slope Turbidite Reservoir Development along a Tectonically Active Margin (Part II) — An Up-System Perspective from the Upper Cretaceous, Offshore Norway

Sømme, Tor O.*1; Jackson, Christopher A.2
(1) Department of Earth Science, The University of Bergen, Bergen, Norway.
(2) Department of Earth Science and Engineering, Imperial College, London, United Kingdom.

The composition, volume and stratigraphic organisation of slope systems deposited along continental margins are expected to reflect the landscape from which the sediment was derived. During the Late Cretaceous, the Møre-Trøndelag margin, northern Norwegian North Sea was dominated by the deposition of deep-marine mudstones; regional supply of sand-rich turbidites only occurred during a c. 3 Myr period in the Turonian. This mudstone-dominated succession has generally been interpreted to reflect the existence of low onshore topography and the absence of efficient, high-energy sediment transport systems onshore at this time. In this talk we focus on the characteristics of the routing system associated with the so-called ‘Turonian sediment pulse’, and we build on our companion talk where we established that the Turonian sediment pulse was associated with the deposition of 11 closely spaced submarine fan systems. The 11 fan systems were fed by sediment that was routed through a number of submarine canyons incised into the eastern basin margin. The areal extent of the onshore drainage catchments that supplied sediment to the fans has been estimated based on scaling relationships derived from modern source-to-sink systems. In addition, sediment volumes have been calculated and compared to expected sediment loads from modern drainage catchments of similar extent. The results of our study suggest that the Turonian fans were sourced by drainage catchments that were up to 2200 km2 and which extended up to 140 km from the shoreline. The estimated inboard extent of the catchments correlates to the innermost structures of a large fault complex, which is thought to have defined the position of the regional drainage divide in this region since the Devonian. Based on our analysis we conclude that increased sediment supply to the Turonian fan systems reflect tectonic rejuvenation of the landscape, rather than eustatic sea-level or climate fluctuations. The duration of fan deposition is thus interpreted to reflect the ‘relaxation time’ of the landscape following tectonic perturbation, and fan system retrogradation and final abandonment is interpreted to reflect the eventual depletion of the onshore sediment source. We have demonstrated that a better understanding of the stratigraphic variability of deepwater depositional systems, and the volume of potential reservoir units, can be gained by taking a complete source-to-sink view of ancient sediment dispersal systems.
 

 

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California