2-D and 3-D modelling of wide-angle seismic data: an example from the Voring volcanic passive margin
|Author(s)||Rouzo Stephane1, Klingelhoefer Frauke1, Jonquet Kolsto Hélène2, Karpuz Ridvan2, Kravik Karl3, Mjelde Rolf4, Murai Yoshio5, Raum Thomas4, Shimamura Hideki5, Williamson Paul6, Geli Louis1|
|Affiliation(s)||1 : IFREMER, Dept Geodynam & Geophys, Plouzane, France.
2 : Total E&P Norge AS, Stavanger, Norway.
3 : Norsk Hydro AS, Bergen, Norway.
4 : Univ Bergen, Inst Solid Earth Phys, Bergen, Norway.
5 : Hokkaido Univ, Inst Seismol & Volcanol, Sapporo, Hokkaido, Japan.
6 : Total E&P PLCs Geosci Res Ctr, Aberdeen, Scotland.
|Source||Marine Geophysical Researches (0025-3235) (Springer), 2006-09 , Vol. 27 , N. 3 , P. 181-199|
|WOS© Times Cited||6|
|Keyword(s)||Gravity modelling, 3 D modelling, Sub screen imaging, Wide angle seismic|
|Abstract||This study presents the modelling of 2-D and 3-D wide-angle seismic data acquired on the complex, volcanic passive margin of the Voring Plateau, off Norway. Three wide-angle seismic profiles were shot and recorded simultaneously by 21 Ocean Bottom Seismometers, yielding a comprehensive 3-D data set, in addition to the three in-line profiles. Coincident multi-channel seismic profiles are used to better constrain the modelling, but the Mesozoic and deeper structures are poorly imaged due to the presence of flood basalts and sills. Velocity modelling reveals an unexpectedly large 30 km basement high hidden below the flood basalt. When interpreted as a 2-D structure, this basement high produces a modelled gravity anomaly in disagreement with the observed gravity. However, both the gravity and the seismic data suggest that the structure varies in all three directions. The modelling of the entire 3-D set of travel times leads to a coherent velocity structure that confirms the basement high; it also shows that the abrupt transition to the slower Cretaceous basin coincides in position and orientation with the fault system forming the Ran Ridge. The positive gravity anomaly over the Ran Ridge originates from the focussed and coincident elevation of the high velocity lower crust and pre-Cretaceous basement. Although the Moho is not constrained by the seismic data, the gravity modelled from the 3-D velocity model shows a better fit along the profiles. This study illustrates the interest of a 3-D acquisition of wide-angle seismic over complex structures and the benefit of the subsequent integrated interpretation of the seismic and gravity data.|