Cretaceous tectonostratigraphy of the Faroe–Shetland region

Abstract

4 Synopsis 5This study presents an appraisal of the Cretaceous tectonostratigraphical development of the Dean et al. 1999; Doré et al. 1999). This distinction is based on the recognition of a 60 regional Early Cretaceous hiatus, including within the Faroe-Shetland region, and which is 61 described more fully in this paper. 62There remain two outstanding issues that are important to our understanding of the tectonic 1993; Dean et al. 1999;Goodchild et al. 1999;Larsen et al. 2010). 79The seeming lack of consensus in the age of onset of Early Cretaceous rifting in the Faroe- In an attempt to address these issues, this paper presents a regional appraisal of the 90Cretaceous succession in the Faroe-Shetland region. The main objective of the study is to 91 establish a regional stratigraphical framework across the region at a scale that enables a first-92 order analysis of its tectonostratigraphical development. To achieve this, the focus is on the 130The post-breakup tectonic movements enhanced the Fugloy and Munkagrunnur ridges as 131 structural highs, and thus helped to create the contemporary bathymetry of the Faroe and 132West Shetland shelves, separated by the deeper-water Faroe-Shetland Channel (Fig. 2). The Data and methods 138This study is based upon the vast wealth of geological and geophysical information acquired The rock record provided a significant basis for this study, which had access to 116 released 145 commercial wells that are distributed widely throughout the eastern half of the Faroe- 146Shetland region ( Fig. 1; Table 1). In the Faroe-Shetland Basin, this includes wells drilled in Table 3, from which a common set of seismic reflectors -183 representing unconformities of regional extent -has been established (see below). The well 184 database together with published information was utilised to calibrate these boundaries. 185In the construction of the regional stratigraphical framework emphasis was placed on the 186 identification of depositional packages bounded by regional (basin-wide) surfaces of 187 discontinuity. The regional stratigraphical scheme (Fig. 6) 234 K1 megasequence 235Age range and internal stratigraphy:The K1 megasequence represents a duration of 236 about 50 myr (late Berriasian-Turonian) (Fig. 6)

An overview of the Upper Palaeozoic–Mesozoic stratigraphy of the NE Atlantic region

“…The Upper Cretaceous sequence is more widely developed and by the end of the Cretaceous period most of the major basement highs, including the Rona High, had been isolated or drowned (Dean et al 1999;Stoker & Ziska 2011). In the Faroe -Shetland region, an angular unconformity separates folded and eroded Turonian and older strata from Coniacian -Maastrichtian rocks in the West Shetland, North Rona, East Solan and West Solan basins, as well as the Foula Sub-basin (Booth et al 1993;Dean et al 1999;Goodchild et al 1999;Grant et al 1999;Stoker 2016). In other West Shetland Shelf basins, much of the Cenomanian -Turonian section is absent, and the unconformity essentially separates Upper and Lower Cretaceous (Fig.…”

“…In the Faroe -Shetland region, the Lower Cretaceous Cromer Knoll Group is dominated by a punctuated coarse clastic assemblage (Ritchie et al 1996;Stoker & Ziska 2011;Stoker 2016) (Fig. 9).…”

“…A maximum-drilled thickness of 1.5 km occurs in the Foula Sub-basin. The Upper Cretaceous consists of argillaceous limestones and mudstones, with rare organic-rich pyritic mudstone (Chalk Group) of Cenomanian-Turonian age in the North Rona, East Solan and West Shetland basins, which pass northwards and upwards into Cenomanian -Maastrichtian calcareous mudstones (Shetland Group) in the Faroe -Shetland Basin (Ritchie et al 1996;Harker 2002;Stoker & Ziska 2011;Stoker 2016) (Fig. 9).…”

“…In the basins underlying the West Shetland Shelf, the Cromer Knoll Group was deposited in marginal-to shallow-marine and basinal marine environments that were subject to fluctuating aerobic/anaerobic bottom waters (Ritchie et al 1996;Harker 2002;Stoker & Ziska 2011). Common intraformational unconformities imply contemporary rifting, albeit localized and intermittent (Dean et al 1999;Harker 2002;Larsen et al 2010;Stoker 2016). An expansion of rift activity across the entire Faroe -Shetland -northern Rockall-Hebrides region probably occurred in the late Barremian/Aptian-Albian, with paralic to marine clastic deposition in all basins, including on the Hatton High.…”

“…14a). However, the increased subsidence of these basins was periodically interrupted by intermittent compression, uplift and erosion, which persisted throughout the Late Cretaceous (Dean et al 1999;Doré et al 1999;Larsen et al 2010;Stoker & Ziska 2011;Stoker 2016). In the northern Rockall Basin, the abundant Late Cretaceous -Paleocene sills throughout the Upper Cretaceous sequence, together with the intrusion of the axial volcanic seamounts, are probably associated with the crustal thinning.…”