A study of the distribution, structure and seismic stratigraphy of syn-breakup and post-breakup sediments in the Faroe sector of the Faroe-Shetland Basin

Jana Olavsdottir

Abstract

Emplacement of the Cenozoic sediments in the Faroese sector of the Faroe-Shetland Basin appear to be controlled by decelerating thermal subsidence of the basin, and local uplift of sediment source areas. However, the actual distribution of sediments appears to be controlled by re-activation of older, Mesozoic structural elements controlling the sediment path way and restricting the depositional areas. The structural elements being re-activated at different times causing considerable structural complexity. Understanding older, Mesozoic,
structural elements control on sedimentation is a potential tool understanding deviations from “normal” thermal subsidence and for predicting the prospectivity in syn- and post-rift succession in the Faroe-Shetland Basin.
On top of the basalt in the Faroe-Shetland Basin there is deposited up to 3.5 km thick sedimentary package, which led into the basin from different directions. With interpretations of 2-D and 3-D reflection seismic data of the post-basalt package it is shown which adjacent areas the various sub-sedimentary packages comes from and where they are located in the basin at specific time intervals.
The adjacent areas to the Faroe-Shetland Basin are constructed of various compositions, where Munkagrunnur Ridge, Fugloy Ridge and Faroe Platform consist of basaltic material while the NW British Platform area is composed of more stable rocks. The derived erosion products from the different adjacent areas will therefore be of diverse quality regarding to a possible future hydrocarbon reservoirs in the intra- and post-basalt strata.
Volcanic derived erosion material has always been avoided as potential hydrocarbon reservoirs due to its bad reputation as a hydrocarbon reservoir. In this study the potential reservoir quality of the intra basalt tuff and epi-volcaniclastic layers onshore Faroe Islands are investigated and some of the intervals hold interesting properties. The results can be used as a first attempt for future studies of intra basalt tuff and epi-volcaniclastic reservoirs.

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