--> Abstract: Cenozoic Uplift and Erosion of the Barents Sea Region - Timing, Causes and Implications, by Jan Inge Faleide; #90177 (2013)

Datapages, Inc.Print this page

Cenozoic Uplift and Erosion of the Barents Sea Region - Timing, Causes and Implications

Jan Inge Faleide

A regional net erosion map has been constructed for the entire Barents Sea region. Exhumation has been estimated by a combination of different techniques, including shale compaction and vitrinite reflectance. The most widespread dataset is based on shot gathers from long-offset seismic reflection surveys. We have analysed the refracted first-arrivals of individual shot gathers with a maximum offset of 12 km and by this we are able to determine the velocity-depth gradients in the upper 2-3 km. The velocity-depth gradients reflect the compaction history and maximum burial depth of the Mesozoic clastics, prior to the uplift and erosion. The various methods give slightly different estimates, and the reasons for this (e.g. the geothermal gradients used for interpreting the vitrinite reflectanse data; the loading effects of grounded glaciers) will be discussed. However, the erosion estimates using different techniques reveal the same regional trends - from little or no erosion on the SW Barents Sea margin, increasing eastwards and northwards in the western Barents Sea, ranging between 1 and 2 km over a large area. In the eastern Barents Sea erosion estimates varies from a few hundred meters in the south to more than 1000 m in the north. The erosional map is combined with an isopach map showing the thickness distribution of Cenozoic sediments along the western and northern Barents Sea margins. The largest thicknesses are deposited as sedimentary fans in front of the major bathymetric troughs like the Bjørnøya and Storfjorden troughs in the west and the Franz-Victoria and St. Anna troughs in the north. A regional seismic stratigraphy is well established for the Cenozoic system along the western margin while the corresponding system along the northern margin is poorly mapped due to sparse data in an area covered by ice most of the year. As a basis for a regional first-order mass-balance we have separated the Cenozoic succession into a glacial and a pre-glacial unit, and we have delineated the drainage areas for each of the depositional systems. Much focus have been on the glacial erosion and deposition at the trough mouth fans along the western and northern margins. However, the large volumes of pre-glacial sediments also derive from erosion of the uplifted Barents Shelf and these must be accounted for when considering the timing of maximum burial. In some areas most of the missing section may be directly related to glacial erosion (e.g. parts of the SW Barents Sea). Here, there is a correlation between the bathymetry and erosion estimates. In other areas the erosion estimates are larger despite shallower waterdepths. Here we must have an important phase of tectonic uplift prior to (and during?) the glaciations. The timing and causes of this tectonic uplift will be discussed. Knowledge about the timing of maximum burial and amount of uplift and erosion is crucial for assessing their impact on the petroleum systems and prospectivity.

AAPG Search and Discovery Article #90177©3P Arctic, Polar Petroleum Potential Conference & Exhibition, Stavanger, Norway, October 15-18, 2013