Voring Plateau diapir fields and their structural and depositional settings

Three fields of sea floor piercing diapiric structures, the Vema, Vigrid and Vivian diapir fields, exist on the marginal Voring Plateau, where individual structures rise as much as 150 m above the sea floor. The large Vema diapir field lies over two major arch structures, the Vema and Naglfar domes, whereas the Vigrid diapir field is located above relatively horizontally stratified basin sequences. Basin modelling shows, depending on the mode of lithospheric response, that 20-35% of the present 1800-3000 m Vema Dome relief is related to tectonism, whereas the remainder is caused by sediment loading and compaction. Backstripping reveals that the Vema Dome has changed from a low-relief structural high in Paleocene-Oligocene to a much narrower Miocene-Present feature. Dome initiation is ascribed to local Paleocene relative structural uplift during the Maastrichtian-Paleocene rift episode. A later phase of tectonic uplift, most likely during the late Oligocene and Miocene, is ascribed to intraplate compressional stress. From seismic profiles and scientific drill holes we infer that Eocene-Miocene sediments, dominated by biosiliceous oozes and muds, are the source for the sea floor piercing structures, which are interpreted as mud diapirs and possibly also mud volcanoes. The ooze mobilization started in late Pliocene, and was induced by differential loading by more dense and less porous prograding late Pliocene-Pleistocene sediments. Abundant small-offset late Oligocene-Pliocene faults and zones of weakness are the most likely pathways for the oozes which have continued to move until Present. (C) 1997 Elsevier Science B.V.