Faroe Islands Passive Seismic Experiment

Principal Investigator: Dr D. Cornwell

Co-investigators: Dr. Richard England (University of Leicester) and Prof. Graham Stuart (Leeds)

Sponsor: SINDRI

Value: £125k

Dates: 01/05/2011 - 31/05/2013

Summary

The crustal structure of the continental block on which the Faroe Islands sits is poorly understood, mainly due to the presence of thick Tertiary basalt sequences at the surface that hinder controlled-source seismic imaging methods (e.g. Maresh et al., 2006). Hydrocarbon prospects in the Faroese sector of the Faroe-Shetland Basin are expected to occur both in between layered basalt flows and in sediments between the base of basaltic sequences and the top of the Precambrian crystalline basement, although the thickness of the basalts, the presence of sediments and the depth and lateral variation of the basement discontinuity is largely unconstrained. In addition to the near-surface crustal structure, variations in crustal thickness and composition are not well known across the Islands. These characteristics have implications for models of uplift and subsidence of the region, particularly as a high-velocity lower crustal layer has been interpreted as igneous intrusions at the the time of continental break-up (e.g. White, et al., 2008). A knowledge of the crustal structure and distribution of material intruded into the lower crust beneath the Faroe Islands would increase the ability to understand the paleogeographic development of the region during continental break-up, as well as their present day elevation. The Faroe Islands Passive Seismic Experiment (FIPSE) will image variations in crustal layer thickness and velocity beneath the Faroe Islands using passive seismological data and the receiver function technique. It will focus on: i) the uppermost ~10 km to investigate basement thickness variations and identify P-to-S converted energy that adds constraints to basalt thickness and the presence of sediments beneath the basalt; and ii) imaging the Moho discontinuity to provide three-dimensional variations in crustal thickness and bulk velocity, together with the identification and classification of high-velocity lower crustal layers. Our interpretation will use the positions of major discontinuities and their associated velocity characteristics to constrain lithological changes beneath the Faroe Islands, particularly in relation to oil-bearing formations, overall crustal structure and uplift and subsidence related to magmatic addition to the crust. Furthermore, we intend to compare and refine our models with those derived from  neighbouring controlled-source seismic methods.