Stratigraphy, tectonics and palaeogeography of the Jurassic sediments of the areas north of Kong Oscars Fjord, East Greenland

Abstract

The lithostratigraphic scheme currently in use for the Jurassic rocks of the Jameson Land area in East Greenland is extended northwards to cover the areas to the north, from Kong Oscars Fjord (72o N) to Store Koldewey (77o N). Most emphasis is laid on the Wollaston Forland area, whereas Traill Ø and Geographical Society Ø are only briefly reviewed. Jurassic sediments are all included in the Jameson Land Group except the latest Jurassic (Middle-Upper Volgian) rocks which are grouped into the Wollaston Forland Group together with Lower Cretaceous rocks of Ryazanian-Valanginian age. Only sediments belonging to the Jameson Land Group are treated here. The group is in the Wollaston Forland area divided into two formations: the Vardekløft Formation below and the Bernbjerg Formation above. The Vardekløft Formation is divided into three members: Pelion Member composed of estuarine sandstones of Bathonian-Late Oxfordian age; Jakobsstigen Member (new) composed of shallow shelf sandstones and mudstones of Early-Late Oxfordian age; and the Muslingebjerg Member (new) composed of barrier-lagoon sandstones and coals of presumed Late Oxfordian age. The overlying Bernbjerg Formation (new) is composed of dark often sandy mudstones of Late Oxfordian-Kimmeridgian (Early Volgian) age. The whole succession is at maximum 1 km thick and reflects deposition in progressively deeper water in a shelf area structurally built of slightly westwards tilted roughly N-S orientated fault blocks. Four regional transgressions controlled by basement faulting can be dated to Bathonian, Early Oxfordian, Late Oxfordian, and Early Kimmeridgian. Each transgression was followed by steady subsidence and prograding sedimentation.