The development of volcanic sequences at rifted margins: New insights from the structure and morphology of the VOring Escarpment, mid-Norwegian Margin

摘要

On the VOring Margin offshore mid-Norway, Paleogene continental breakup was characterized by the extrusion of large volumes of flood basalts erupted in different depositional environments. The transition from subaerial to submarine emplacement environment is marked by the formation of the VOring Escarpment which records the early encroachment of flood basalt into the basin and the buildup of a lava delta system. The increased availability of new and reprocessed high-quality seismic data allows a more detailed characterization of the along-strike and across-strike continuity and variability of the different volcanic seismic facies units. Detailed seismic interpretation shows that the similar to 350km long NE-SW trending VOring Escarpment is a prominent feature along the VOring Margin with a height ranging between 200 and 1600m. Structurally, the VOring Escarpment is segmented along strike into five segments (E1-E5) with different controlling factors leading to variation in accommodation space. Relative sea level change and magma supply are the major controlling factors for segments E2 and E4 which are characterized by a well-developed lava delta system and significant escarpment height. Tectonic movements along the Jan Mayen Fracture Zone resulted in second-order segmentation of the E1 segment into pseudoescarpments with a very thin lava delta system and limited escarpment height. Segments E3 and E5, situated along the flanks of Cretaceous/Paleocene highs, are controlled by the structural highs, which were possibly reactivated during breakup time. Our mapping results provide crucial information about the paleogeography and yield important information regarding the paleo-water depth and depocenter locations prior to and during the breakup of the VOring Margin.