An integrated study of the late Paleocene to early Eocene Flett (T40/t45) and balder (T50) formations of the Flett sub-basin, Faroe-Shetland Area, north Scotland

Abstract

3D seismic and well data (wireline logs, biostratigraphic information and core photographs) were employed to evaluate the Late Paleocene - Early Eocene Flett (T40/T45) and Balder (T50) Formations with the aim of understanding their depositional setting within the Flett Sub-Basin, located offshore North of Scotland. The thicknesses of the formations varied across the basin, with the Flett and Balder Formations displaying thickness ranges of 0 - 800 m and 0 - 300 m respectively. The wireline signatures showed shale and sandstone as the main lithologies within these formations with volcanics observed in the shallower NE - SW part of the basin. The shales and sandstones of the Lower Flett Formation (T40) were believed to have been deposited on the slope within the deep marine environment during the relative sea level fall. The sediments of the Upper Flett Formation (T45) were deposited on the shallow marine shelf environment. The transition from slope deposit (T40) to shelf deposit (T45) was attributed to the effect of uplift in the Shetland area in the Early Paleocene time. The Balder Formation (T50) were composed of sandstone and interpreted to be deposited on the shelf to deltaic environment. Sedimentological and wireline interpretation indicated that the main sediment source for the Flett Sub-Basin was the Greenland and West Shetland Platform with local inputs from the surrounding structural highs.

Keywords: Flett Sub-Basin, Flett Formation, Balder Formation, Depositional Environment