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Research Area: Exploration

Source to sink: Sediment volume partitioning in time and space

Project Number: 6256
Project Duration: 1. April 2009 - 30. March 2012

Project Director: William Helland-Hansen, UiB
Division Head: Lasse Amundsen

Objective

The Source-to-sink (S2S) concept represents a new generation of basin studies that takes into account sediment erosion, transport and deposition from catchment to deep basin. Source-to-sink studies represent an extension of sequence stratigraphy in the sense that the profile segments and the associated depositional environments are not viewed as separate entities, but are regarded as a dynamic link where each component is equally important. The feedback mechanisms between production, storage and transfer of sediments and the interaction between sedimentary environments are essential issues when approaching systems from this perspective. The ultimate goal is to get a broader understanding of the origin and volume of sediments eroded from the catchment and how these volumes are partitioned in the sink (continental, marine and deep marine) at multiple time-scales.

Armed with in-depth-understanding of modern S2S rift-systems together with techniques and methods designed to unravel the unknown parameters in ancient rift systems  (provenance, thermogeochronolgy, sedimentology/sequence stratigraphy, biostratigraphy, quantitative modelling), Late-Jurassic to Cenozoic submarine fan systems  (rift and post-rift) on the Norwegian shelf are studied. Drainage areas are related to depocenter morphology/volume with focus on small, tectonic active systems that were responsible for delivering sediments to deep marine environments which are potential reservoirs on the Norwegian shelf. By understanding how different parameters (e.g catchment size, relief, water discharge and sediment load, shelf width, slope length, fan volume etc.)  relate to each other in more detail, the range between them and the uncertainty spectre they are associated with, these can be better implemented into risk analysis and exploration on frontier basins with little data. As an example, it has been shown from modern systems that the size of the drainage basin and the spacing between their rivers is related to the width of the mountain range in which they occur. If similar relationships can be extrapolated to ancient systems prediction of spacing between river systems and their associated basin floor fans in ancient subsurface system can be made.

Shelf-Edge and Shorelines Trajectories

The shoreline trajectory concept, the shoreline trajectory being the cross-sectional, depositional-dip oriented path of the shoreline as it migrates, allows traditional shoreline migration classes, such as "normal regressive", "forced regressive", and "transgressive" to be viewed as part of a continuous spectrum. Using this concept, facies and facies association variations can also be interpreted in terms of this continuous spectrum. Within the context of larger scale shelf-margin-scale clinoforms, the migration of the shelf-slope-break may be used to determine a trajectory ("the shelf-edge trajectory"), which becomes evident when the successive positions of shelf-edges are viewed in a depositional-dip oriented profile.

By examening the relationship between shoreline/shelf-edge trajectories, lithofacies and seismic signatures we will improve lithological prediction from well- and seismic data. Especially the relation between cross-sectional seismic data and attribute maps are examined and linked to depositional environment and lithology. Further outcrop analouges are applied to support potential predictive links between paralic/continental and shallow marine deposits. Studies are carried out on subsurface data from offshore Venezuela and the Norwegian shelf and outcrop data from Book Cliffs, Utah.

Scholar: Tor Oftedal Sømme

E-mail: tor.somme@geo.uib.no
Institution: UIB

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