Along-slope variation in the late Neogene evolution of the mid-Norwegian margin in response to uplift and tectonism

Abstract

AbstractAs part of the Norwegian Deep Water Programme, a regional geological and geophysical interpretation of the mid-Norwegian margin resulted in the establishment of a late Paleogene to Holocene stratigraphic framework for the margin, and identification and mapping of a range of possible geohazards, including slides. At the Vøring margin in the north, there has been the build-out of a huge prograding wedge of sediment in Plio-Pleistocene times. The sediments of the wedge are assigned to the Naust Formation, which has been subdivided into eight units (A-H), and includes only a few palaeoslides. To the south of the Vøring margin lies the Storegga Slide Complex and the North Sea Fan, and the whole of this southern region shows evidence of several major palaeoslides. The sediments are also referred to the Naust Formation, which here are subdivided into nine units (O-W) that have been partly correlated with equivalent Naust units to the north. The oldest Naust unit in the south, Naust Unit W, is largely made up of slide deposits that provide evidence for the earliest identified large-scale slope instability in the Storegga Slide Complex. This instability was penecontempooraneous with the initiation of the prograding wedge to the north, and both features are postulated to be the result of uplift of the Norwegian mainland. In the case of the Storegga Slide Complex, which lies close to the main area of uplift, oversteepening of the margin, together with seismicity associated with the Jan Mayen Fracture Zone and Møre-Trønderlag Fault Complex, may have initiated sliding that has since occurred intermittently up to Holocene times, over a time interval when there has additionally been much glacio-isostatic movement.