Structural geology and basin development of the Norwegian Sea

Abstract

The investigated area comprises the 300-500 km-wide passive margin offshore Mid Norway as well as the 70-40 km-wide margin northwest of the Lofoten-Vesterålen archipelago. Following the Caledonian Orogeny, Greenland was close to Mid Norway and central-northern Norway. The orogeny climaxed with the Early Devonian continent collision with subduction of the Baltic craton beneath Laurentia, and a mountain range several kilometres high evolved. The mountain range remained a positive topographic element throughout the Late Palaeozoic and Early Mesozoic. Non-marine Carboniferous sediments were deposited onshore East Greenland, but there is no evidence of sedimentation during this period offshore Mid Norway. Three significant rift episodes, i.e., Late Permian-Early Triassic, Middle-Late Jurassic and Campanian-Paleocene are evident, with intervening (c. 70 Ma) periods of overall tectonic quiescence. Permo-Triassic sediments, 4000-6000 m in thickness, were deposited in an eastern basin area juxtaposed against basement across large normal faults close to the Norwegian mainland. The topography created by the Late Permian-Early Triassic rift episode became levelled during the Middle Triassic, and younger sediments were deposited over a relatively flat area represented by the present Trøndelag Platform and the Halten and Dønna terraces. Due to Jurassic extension there was a change to a setting where the Halten and Dønna terraces became separate structural entities, down-faulted and with a complex basin-floor topography. Until the climax stage of the Jurassic rift episode, the Caledonian mountain range might have occupied the area between the Halten Terrace and Liverpool Land, at the east coast of Greenland. The subaerially exposed land mass was eroded and acted as an important sediment source. Middle and Lower Jurassic, but also Triassic sediments entering into the basin from the west contain conglomerates and pebbly sandstones deposited under fluvial, deltaic and marginal marine conditions, and clinoforms are recorded along the basin margin on the western Halten Terrace. The largescale paleogeography was a central basement high, which separated the basin onshore East Greenland and the basin area offshore Mid Norway. Due to erosion and accelerated Late Jurassic rifting the basement high ceased to exist as a source area, leaving the narrow Sklinna Ridge as an easternmost remnant in the footwall of the Klakk Fault Complex. This stage of development is regarded as the first indication of a large and continuous marine basin between Mid Norway and Greenland after the Caledonian Orogeny.

The evolution of catchment‐depositional system relationships on the dip slopes of intra‐rift basement highs: An example from the Frøya High, Mid‐Norwegian rifted margin

“…Throughout the Early Cretaceous, the crust underneath the Møre Basin became hyperextended with substantial displacement accumulated on the KFC (Grunnaleite & Gabrielsen, 1995;Péron-Pinvidic et al, 2013;Osmundsen et al, 2016;Muñoz-Barrera et al, 2020, 2021Bunkholt et al, 2022). During this time, uplift of the Frøya High began to decrease and it ultimately became buried during the Mid-Late…”

“…However, uplift and rotation of the back-tilted footwall dip slope also offers accommodation for sedimentary systems fed by drainage directed away from the footwall crest. (Ravnås & Steel., 1998;Gawthorpe & Leeder, 2000;Muravchik et al, 2018;Smyrak-Sikora et al, 2018;2021;Rapozo et al, 2021). The tectono-sedimentary setting of dip slopes developed along the footwall of major faults is considerably different to that of immediate hangingwall systems such as fault-scarp degradation related fans, or rift-margin deltas.…”

“…Characterisation of the Frøya High bedrock stratigraphy highlights that Late Jurassic catchments consisted of relatively easily erodible sedimentary rocks of Upper Palaeozoic -Lower Mesozoic age within the Almond Basin, as opposed to the crystalline rocks elsewhere, outside the Almond Basin, on the southern Frøya High (Jones et al, 2020;Munoz-Barrera et al, 2020, 2021. We conclude on the basis of spatial patterns of Viking Group thickness, the position of a NE-SW trending ridge following restoration, and comparison with other rift system catchment morphometrics, that the interpreted Upper Jurassic clastic shoreline system was supplied by at least four distinct drainage basins, each around ~10 km, long spaced 5.5 -7.5 km along the dip slope of the Frøya High.…”

The Moho Architecture and Its Role for Isostasy—Insights From the Lofoten‐Vesterålen Rifted Margin, Norway

“…The surface geology in Nordland and Troms comprises the Caledonian Upper and Uppermost Allochthons, which were thrust on top of Precambrian Baltican basement during the Silurian‐Devonian Caledonian orogeny (e.g., Froitzheim et al., 2016; Gee, 2015; Roberts, 2003; Steltenpohl et al., 2011). After initial post‐orogenic extension of the Caledonides in the Devonian (Fossen, 2010; Osmundsen & Ebbing, 2008), continental rifting formed deep sedimentary basins in the Permian‐Triassic to Cenozoic (Færseth, 2012; Gernigon et al., 2020; Schiffer et al., 2020). Rifting in the present‐day Lofoten‐Vesterålen continental margin (LVCM) culminated in continental breakup in the early Eocene, likely as one of the earliest segments forming the Northeast Atlantic Ocean (e.g., Bergh et al., 2007; Gernigon et al., 2020; Hansen et al., 2011).…”

“…The LVCM was structurally inverted during multiple phases in the Cenozoic (Doré & Lundin, 1996; Færseth, 2012; Stephenson et al., 2020). The complex landscape in Nordland and Troms was finally modified by Quaternary glacial erosion creating deep fjords and stripped mountain ranges.…”