The Skade sections in wells 25/2-10 S and 25/1-8 S contain common mollusc fragments and lignite, and have probably been deposited in shallower water close to, or as parts of, a delta. In most parts, the deposits are turbiditic in origin and were probably deposited in quite deep parts of the shelf. The deposition of the Skade Formation represents a southern shift in coarse clastic influx to the basin from the East Shetland Platform, relative to Oligocene time ( Map 1). They comprise a succession of amalgamated sands alternating with thinner mudstones. The areal extent and thickness of the sands are shown in Fig. These sands are referred to as the Skade Formation and reach a gross thickness of up to 300 m (well 16/1-4). In large parts of the Viking Graben, a sandy section, sourced from the East Shetland Platform, makes up a great proportion of the Lower Miocene unit. In the Tampen area the Lower Miocene strata comprise mud-prone lithologies. In the northernmost North Sea, between 61✣0' and 62ºN, the unit has been completely eroded (Rundberg & Eidvin 2005). On seismic sections, the top of the unit can be defined by erosional truncation, as illustrated schematically in Profile 4. It may be present locally in depressions between diapirs. Just south of 61ºN and northwards, the Lower Miocene unit is only present in the central basin and absent at the margins to the west and east (Fig. It is overlain by Middle Miocene sediments in the centre of the basin and Pliocene sediments at the margins (Profile 4). In the southern Viking Graben, it conformably overlies Oligocene strata. The Lower Miocene (unit UH-4 of Rundberg & Eidvin 2005) comprises the topmost part of the Hordaland Group. In the North Sea, the Oligocene – Lower Miocene boundary is marked by major shifts in sedimentation, with onset of sand deposition in the Viking Graben and Jutland ( Map 1). Lower Miocene pelagic sediments are also present at several DSDP and ODP sites in the Vøring and Møre basins (Talwani et al. There are few signs of erosional products related to any of the two hiati, which indicates that the Mid Miocene unconformity in this area is more related to non-deposition rather than representing a major episode of erosion (Bugge et al. The unconformity below the wedge seems to represent more active erosion than at the time of the Mid Miocene unconformity on top. Stratigraphically and agewise, the wedge belongs to the Brygge Formation. It has not been investigated in any well, but from its geometry it might be considered to be similar to the one in the Draugen Field (see figure 5 in Eidvin et al. About 50 km northeast of the Draugen Field another wedge with the same stratigraphic position and appearance has been observed. The stratigraphic gap in well 6407/9-5 ranges from the Lower Oligocene to the Lower Miocene below the wedge, and from the Lower to the Upper Miocene above ( Fig. It is wedge shaped and overlies a well defined erosional unconformity (see figure 4 in Eidvin et al. In the wells 6407/9-/9-3 (not investigated) in the Draugen Field ( Map 1) there is an up to 22 m-thick, fine-grained, hemipelagic section of Lower Miocene sediments. It is not clear if there is a hiatus or continuous deposition between the Lower Oligocene and Lower Miocene part of the formation (Fig. The formation is investigated in well 6510/2-1 (Map 1) and consists of glauconitic (dominant) and quartzose sand of late Burdigalian age. The progradation of the Molo Formation along the inner continental shelf of the Norwegian Sea continued into the Early Miocene, and extended farther south than in the Oligocene. In the Senja Ridge, in wells 7117/9-/9-2, the Upper Pliocene sediments rest on Eocene sediments with an erosional boundary (see also the discussion section). In well 7216/11-1S, there is a hiatus below the Mid Miocene unconformity (Ryseth et al. Possible Lower Miocene has only been recorded in well 7316/5-1 ( Map 2), which penetrated an Oligocene – Lower Miocene section below the base Upper Pliocene erosional surface. The Miocene section of the Barents Sea shelf has been preserved only along the western margin in local basins formed by tectonism along the Senja Fracture Zone.
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