Late Paleozoic development of the Finnmark Platform, southwestern Barents Sea, Norway

Abstract

Following the recent Gohta and Alta discoveries in the Loppa High by Lundin Norway AS in 2013 and 2014 respectively, there has been an enhanced interest for the Upper Paleozoic succession in the Norwegian Arctic Shelf region. Several previous studies have confirmed that the eastern Finnmark Platform provides an excellent location for studying evolution of a carbonate platform with changing platform morphology and buildup distribution in space and time. Stratigraphical differences have been noted across the platform; however limited information exists about the Upper Paleozoic succession and its development on the central and western platform, in comparison to on the eastern Finnmark Platform. In this study, 2D and 3D seismic data have been combined with well data in order to develop a regional understanding of the Late Paleozoic development of the entire Finnmark Platform. The aim is to improve the paleogeographic understanding of the region by obtaining knowledge about the architecture of the Upper Paleozoic carbonate succession across the platform, define structural and stratigraphical boundaries, and determine controlling mechanisms responsible for observed varying sedimentation patterns. Enhanced knowledge about the historical development of the Finnmark Platform in space and time is beneficial for an improved understanding of the extension of the Late Paleozoic carbonate platforms, as well as the geological evolution of the area. Significant differences, both structurally and stratigraphically, have been observed across the platform. Consequently, three provinces could be defined. The eastern province represents a stable platform dominated by Upper Paleozoic warm- and cold-water carbonate buildups and deposits. These carbonate units are observed to pinch-out towards a fault-controlled structural high in the central province. The structurally complex western province is dominated by clastic sediments. Late Paleozoic marine incursion from the east, responsible for development of favorable conditions for carbonate buildup growth and deposition in the east, did neither reach the western, nor most of the central province. During the Late Carboniferous-Early Permian times, these areas represented a positive subaerially exposed feature and were not site for deposition. Indications of Early Permian marginal uplift, similar to what has been reported from Bjørnøya, have been observed and seem to have influenced the overall depositional regime on the Finnmark Platform at the time. Eventually, in the late Early Permian, the central and western provinces became submerged. Spiculites were deposited across the entire Finnmark Platform, although presumably under contrasting depositional settings.