Magmatic activity during the breakup of Greenland-Eurasia and fluid-flow in Stappen High, SW Barents Sea

Abstract

A great deal of magmatic activity was recorded along the northern Atlantic margins during the Cenozoic opening of the Norwegian- Greenland Seas. This work uses a recently acquired two-dimensional seismic reflection dataset to characterize magmatic rocks and fluid-flow features on the western margin of Stappen High. ‘Hard kicks’ are positive seismic high-amplitude anomalies related to igneous rocks in the subsurface while ’soft kicks’ are negative high-amplitude anomalies interpreted as fluid-related anomalies. The hard kicks are the most prominent anomalies in the study area, and they are distributed in a N-S zone that is coincident with the trend of the Stappen High. The hard kicks include extrusive and intrusive rocks such as lava flows, dykes, and volcanic sills. The sills have saucer, bowl, transgressive, tabular, and convex geometries. Extrusive igneous rocks and other deeply-seated volcanic sills are buried to a depth of greater than 3000 ms. Soft kicks are bright spots and enhanced reflections found close to angular unconformities, channels, clinoforms, and canyons. Hydrothermal vents and vertical clusters of soft-kicks/gas-charged sediments are evidence of vertically focused fluid-flow in the study area. This work finds that large-scale magmatic edifices recorded in other northern Atlantic margins are also present in the study area as volcanoes, volcanic plateaus and cascade-transgressive sills. Volcanic rocks in Stappen High were emplaced during the Late Eocene, Oligocene and Early Pliocene delimiting the areas into a southern part that is magma-rich and a northern hydrocarbon-rich province.