Vøring Plateau Continental Margin: Seismic Interpretation, Stratigraphy, and Vertical Movements

Abstract

Seismic mapping tied to drilling data has provided a depositional, structural, and volcanic framework that describes the Wring Plateau continental margin since Late Jurassic time. The Vdring Basin was structured by Late Jurassic-Early Cretaceous extension and subsequent subsidence in the Cretaceous. It is divided into two basin provinces by the Molde-Bodd high. The opening of the Norwegian-Greenland Sea during the early Tertiary was preceded by uplift of the outer Wring Basin accompanied by extensional listric faulting in the Cretaceous sediments and intrusive activity. The early Tertiary extension was restricted to the outer Wring Basin, subsequently forming the Tertiary marginal basin. The igne ous activity is also restricted to this basin, gradually approaching the Wring Plateau Escarpment toward the time of breakup. Initial subaerial sea-floor spreading created the upper volcanic series at ODP Site 642, parts of the flow-sill complex landward of the escarpment and also caused deposition of ashes and tuffs in the Wring Basin. The post-open ing margin history is characterized by the progressive submergence of the Wring Plateau marginal high which for long periods was elevated with respect to the Wring Basin. The southern marginal high became fully sediment covered dur ing the early Miocene, whereas the northern part was not covered before the Pliocene. The basal sediments are of terrig enous origin, partly derived from erosion of the exposed lavas. Off the summit, a change to hemipelagic and pelagic compositions took place during the middle and late Eocene. The overall sediment record at the high is characterized by local erosion, redeposition, and instabilities. We propose that early Tertiary strike-slip motion, which triggered mass movements lasting into the early Miocene, is responsible for the spectacular north-south domes in the Wring Basin. Fi nally, a renewed major pulse of sedimentation and subsidence centered on the shelf edge commenced in latest Miocene time.

Crustal Transect across the Lofoten Volcanic Passive Continental Margin, N. Norway, Obtained by Use of Ocean Bottom Seismographs, and Implications for Its Evolution.

“…It is commonly accepted that Cenozoic sea-floor spreading in the Norwegian margin was initiated in the period 58.5-56Ma (Eldholm et al, 1990). The seaward dipping reflectors (SDR) observed in the upper crust along the Norwegian margin, are formed during the earliest stage of the sea-floor spreading (e.g., Skogseid and Eldholm, 1989). ODP leg 104 drilled through the upper sequence of the SDR, and the core samples confirmed that the SDR represent interbedded mid-oceanic type theoleitic lava flows and pyroclastic sediments (Eldholm et al, 1989).…”

“…The late Jurassic-early Cretaceous (150-90Ma) extension lead to major faulting activity, generally creating slightly rotated fault blocks and causing subsequent subsidence along major rift systems (Ronnevik et al, 1983;Boen et al, 1984;Hinz et al, 1984;Mutter, 1984;Skogseid and Eldholm, 1989). The early Cenozoic extension episode lasted about 10 Ma, and ended in the earliest Eocene (58Ma) with extrusive volcanism forming landward floor basalts (Eldholm et al, 1989).…”

“…The seaward dipping reflectors (SDR) observed in the upper crust along the Norwegian margin, are formed during the earliest stage of the sea-floor spreading (e.g., Skogseid and Eldholm, 1989). ODP leg 104 drilled through the upper sequence of the SDR, and the core samples confirmed that the SDR represent interbedded mid-oceanic type theoleitic lava flows and pyroclastic sediments (Eldholm et al, 1989). The subsequent sea-floor spreading along the Vining margin as well as the Lofoten margin proceeds rather simply with oceanic crust generated symmetrically along the Mohns ridge (Fig.…”

“…During the last three decades, the Mid-Norwegian continental margin has been studied relatively well by seismic surveys (e.g., Sellevoll, 1983;Mutter et al, 1988;Olafsson et al, 1992;Mjelde et al, 1992;Goldschmidt-Rokita et al, 1994;Kodaira et al, 1995), gravity and magnetic surveys (e.g., Dehghani et al, 1988;Mokhtari et al, 1989), and sea-floor drilling (e.g., Eldholm et al, 1987Eldholm et al, , 1989Talwani and Udinstsev, 1989). Consequently, the margin has become one of the most well known passive continental margins in the world.…”

The Cenozoic western Svalbard margin: sediment geometry and sedimentary processes in an area of ultraslow oceanic spreading

“…1) stretches for a distance of about 1,800 km through this part of the Atlantic Ocean and has over the last 55 million years shaped the NorwegianGreenland Sea into its present configuration. Through its development, the ridge affected sediment distribution and source areas (Skogseid and Eldholm 1989;Eldholm et al 1994;Bruvoll et al 2009). The Fram Strait and the Greenland-Scotland Ridge (Fig.…”