Igneous activity in the East Rockall trough: Nature, origin, and impact on the petroleum system

During the early Cenozoic, igneous activity of varying intensity was widespread along the NE Atlantic margin. Igneous features are well imaged on 3D seismic data on the eastern margin of the Rockall Trough. Magmatism was both extrusive and intrusive with associated intrusion-related vent structures, which may have significant implications for the petroleum system of this frontier province. The extrusions occurred during the Late Paleocene and Early Eocene from a Hebridean Platform source, characterised by NE-SW trending flows with flow lengths of up to 18 km. The most prominent intrusions are Early Paleocene in age and were sourced from the Hebridean Seamount with aerial extents of up to 22 km2. Intrusion-related vent structures are dome shaped features typically overlying the edges of saucer-shaped intrusions. Their formation is related to fluid expulsion up to the contemporaneous seabed from the intrusion tips as it cools. As the vents occur on the seafloor, their presence can be used to date associated intrusions. We will demonstrate the igneous activity and how it can impact the petroleum system in both positive and negative ways including trap formation, top seal integrity and poor seismic imaging of pre Cenozic successions below the igneous features.