Morphology and Basement Structures of the Goban Spur Continental Margin (Northeastern Atlantic) and the Role of the Pyrenean Orogeny

Abstract

A new bathymetric map, based mainly on Seabeam data, has been established for the Goban Spur area during a postcruise survey of DSDP Leg 80. Using both Seabeam data and a new series of eight seismic profiles obtained perpendicular to the continental margin, we have constructed a new detailed structural map of the Goban Spur continental margin which clearly reveals Caledonian and Variscan trends. Both the thinning of the Goban Spur continental crust, from Early Cretaceous (late Cimmerian phase) to middle Albian time, and subsequent widening of the adjacent oceanic domain, from middle Albian to Campanian time, resulted from tensional movements in a N70° direction which followed Caledonian trends. During the rifting phase, the tops of the tilted fault blocks remained close to sea level. The rapid subsidence of the margin seems to have occurred in the early Albian during the last stage of rifting.Eocene intraplate deformation affected the whole Goban Spur continental margin, but is particularly evident at the Pastouret Ridge, a reactivated oceanic fracture zone. The oceanic domain underwent a slight intraplate compression, which fractured the old oceanic crust through its entire thickness, probably along previous zones of weakness, such as fracture zones.

The deep structure of non–volcanic rifted continental margins

“…Lond. A (1999) (Sibuet et al . 1985) and locations of the WAM deep reflection profile (thin line with shot numbers) ); coincident and crossing refraction profiles 1, 2 and 3 (thick lines) (Horsefield et al .…”

Thinning of the Goban Spur continental margin and formation of early oceanic crust: constraints from forward modelling and inversion of marine magnetic anomalies

“…Profile WAM cuts across the Goban Spur passive margin almost orthogonally. Although a second-order geological feature lying obliquely to the margin has been identified on a detailed tectonic map ), the margin is basically a 2-D feature, as shown by the bathymetric (Sibuet et al 1985). tectonic (Fig.…”

Physiography and Structure of the Western Iberian Continental Margin off Galicia, from Sea Beam and Seismic Data

“…General structural map of the northeast Atlantic, showing identified magnetic anomalies (Guennoc et al, 1978(Guennoc et al, , 1979Sibuet and Ryan, 1979a;Verhoef et al, 1986). Canyon trends are shown on the continental margins (Lallemand and Sibuet, in press): (1) north Iberian Paleogene thrusting front; (2) late Hercynian faults on land and continental shelves, after Parga (1969), Arthaud and Matte (1975), Montadert et al (1979d), and Sibuet et al (1985); (3) approximate present limit of Jurassic sediments in the Western Approaches and Celtic Sea Basins (Pegrum and Mountenay, 1978); (4) continent/ocean boundary (Sibuet et al, 1985); (5) flow lines of initial opening of Bay of Biscay and northeast Atlantic Ocean (Olivet et al, 1984;Savostin et al, 1986); (6) directions of canyon orientations on the continental margins (Lallemand and Sibuet, in press). Figure 6.…”

“…Numerous areas were uplifted during late Eocene, including both the oceanic do main and the continental margins (Montadert et al, 1979d;Groupe Galice, 1979;Groupe Cybere, 1984;Sibuet et al, 1985). In the Galicia Bank area, the large faults that run along the northwest edge of Galicia Bank continue to the southwest, where large deformations with clear reverse faulting affect the Meso zoic and Eocene sedimentary layers (Montadert et al, 1979d;Rehault and Mauffret, 1979;Groupe Cybere, 1984).…”