Cretaceous lithostratigraphy of North-East Greenland

Abstract

An updated and revised lithostratigraphic scheme is presented for the Cretaceous of North-East Greenland from Traill Ø in the south to Store Koldewey in the north. The Ryazanian to lower Maastrichtian succession is up to several kilometres thick and comprises four groups, 12 formations and 18 members. The groups record the tectonic evolution of the East Greenland depocentre on the western flank of the evolving proto-Atlantic seaway. The Wollaston Forland Group encompasses the uppermost Jurassic – lowermost Cretaceous rift-climax succession and contains the Lindemans Bugt and Palnatokes Bjerg Formations; two new members of the latter formation are erected from Store Koldewey. Post-rift Cretaceous strata are referred to the new Brorson Halvø Group and the Home Forland Group. The Brorson Halvø Group (uppermost Hauterivian – middle Albian) is dominated by slope and basinal mudstones of the new Stratumbjerg Formation but also includes fluvio-deltaic and shallow marine sandstones of the revised Steensby Bjerg Formation on northern Hold with Hope and submarine slope apron breccias and conglomerates of the revised Rold Bjerge Formation on Traill Ø. The Home Forland Group covers the middle Albian – Coniacian succession. The basal unconformity records an important mid-Albian tectonic event involving intrabasinal uplift, tilting and erosion, as exemplified by the middle Albian conglomerates of the new Kontaktravine Formation on Clavering Ø. The Home Forland Group is dominated regionally by mud-dominated slope to basinal deposits of the elevated and revised Fosdalen Formation; it also includes lowstand basin-floor fan sandstones of the new upper Albian Langsiden Member. The new Jackson Ø Group (upper Turonian – lower Maastrichtian), records a phase of basin reorganisation marked by a significant fall in sedimentation rate in North-East Greenland, probably linked to rift events in, and bypass to, the central proto-Atlantic rift system. The base of the group is an erosional unconformity on Traill Ø and Geographical Society Ø overlain by submarine slope-apron conglomerates of the Turonian Månedal Formation. The base is conformable on Hold with Hope but is defined by a condensed interval (the Coniacian Nanok Member) that is succeeded conformably by slope and basin-floor turbidite sandstones of the Coniacian–Santonian Østersletten Formation and slope to basinal mudstones of the Campanian – lower Maastrichtian Knudshoved Formation. The new Leitch Bjerg Formation of Campanian slope-apron conglomerates and sandstones in eastern Geographical Society Ø erosionally overlies the Knudshoved Formation.

Upper Cretaceous bottom current deposits, north‐east Greenland

“…Late Cenomanian -Coniacian The upper Cenomanianlower Turonian interval is poorly represented in north-east Greenland; excepting the succession described here, the interval is known only from scattered outcrops on Traill Ø. The exposed deposits provide a record characterized by deep sea mudstonedominated sedimentation, an absence of largescale turbidite systems, and increasing stratigraphic condensation (Parsons et al, 2017;Bjerager et al, 2020). Whitham et al (1999) reported that theseand other post-Valanginian basinal depositscharacteristically comprise thinly interbedded mudstones and very fine-grained to fine-grained sandstones showing mud-draped ripple cross-lamination; these workers concluded that their emplacement involved bottom current influence.…”

“…As for other post-Valanginian mudstone-dominated intervals, Whitham et al (1999) interpreted Campanian deposits to have been bottom current influenced. The later Campanian witnessed significant renewed fault activity and the appearance of coarse-grained gravity-flow systems (see Bjerager et al, 2020), but this interval was not encountered in the studied core.…”

“…The scheme was recently redefined by Bjerager et al . (2020), in which the Fosdalen, Østersletten and Knudshoved members are elevated to the rank of formation and redefined to include correlative deposits elsewhere in north‐east Greenland (Fig. 2B).…”

“…(B) Revised scheme after Bjerager et al . (2020). Refined chronostratigraphy is based on Nøhr‐Hansen et al .…”

“…Recently, an upper Albian – lower Cenomanian basin‐floor fan system on the north coast of Hold with Hope, and slope‐related depositional systems near the Nanok‐1 drill site have been reported (Lygnaelv River; Fig. 1; Bjerager et al ., 2020). The mid‐Albian rift event has been interpreted to have been followed by thermal subsidence that allowed the accumulation of a deep sea mudstone‐dominated succession in the area during the Late Cretaceous (Parsons et al ., 2017).…”