Nature of the S reflector beneath the Galicia Banks rifted margin: Preliminary results from prestack depth migration

Hoffmann, H. J.; Reston, T. J.

doi:10.1130/0091-7613(1992)020<1091:notsrb>2.3.co;2

Cited by 49 publications

(44 citation statements)

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“…A strong subhorizontal reflector beneath the tilted fault blocks of the Galicia Bank margin has been interpreted as an important detachment fault (e.g. Boillot et al, 1988;Sibuet, 1992;Hoffman et al, 1992;Reston et al, 1996;Whitmarsh et al, 2001). This detachment fault is observed over 50 km normal to the margin.…”

Section: Non-volcanic Marginsmentioning

confidence: 96%

Continent–ocean-transitions: Review, and a new tectono-magmatic model of the Vøring Plateau, NE Atlantic

Mjelde

Raum

Murai

et al. 2007

Journal of Geodynamics

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Section: Non-volcanic Marginsmentioning

confidence: 96%

Continent–ocean-transitions: Review, and a new tectono-magmatic model of the Vøring Plateau, NE Atlantic

Mjelde

Raum

Murai

et al. 2007

Journal of Geodynamics

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“…Figure 1 shows a cross-section through one of the best investigated margins, the Cretaceous Galicia Margin west of Portugal. The Galicia Margin and the adjacent Iberian Abyssal Plain Margin have been the subject of intense research including all of the above mentioned techniques, and often serve as reference margins in studies on magmapoor rifting (ODP legs 103, 149, and 173, Boillot et al 1980, 1995Mauffret and Mondatert 1987;Hoffmann and Reston 1992;Reston et al 1996;Pickup et al 1996;Whitmarsh et al 2000;Pérez-Gussinyé et al 2006). Researchers working on ancient margins now preserved in the Alps often compare their results with findings from the Galicia Margin (Manatschal and Bernoulli 1999;Whitmarsh et al 2001;Manatschal 2004).…”

Section: Introductionmentioning

confidence: 94%

Control of rheological stratification on rifting geometry: a symmetric model resolving the upper plate paradox

Nagel

Buck²

2007

Int J Earth Sci (Geol Rundsch)

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Numerical experiments reproduce the fundamental architecture of magma-poor rifted margins such as the Iberian or Alpine margins if the lithosphere has a weak mid-crustal channel on top of strong lower crust and a horizontal thermal weakness in the rift center. During model extension, the upper crust undergoes distributed collapse into the rift center where the thermally weakened portion of the model tears. Among the features reproduced by the modeling, we observe: (1) an array of tilted uppercrustal blocks resting directly on exhumed mantle at the distal margin, (2) consistently oceanward-dipping normal faults, (3) a mid-crustal high strain zone at the base of the crustal blocks (S-reflector), (4) new ocean floor up against a low angle normal fault at the tip of the continent, (5) shear zones consistent with continentward-dipping reflectors in the mantle lithosphere, (6) the mismatch frequently observed between stretching values inferred from surface extension and bulk crustal thinning at distal margins (upper plate paradox). Rifting in the experiment is symmetric at a lithospheric scale and the above features develop on both sides of the rift center. We discuss three controversial points in more detail: (1) weak versus strong lower crust, (2) the deformation pattern in the mantle, and (3) the significance of detachment faults during continental breakup. We argue that the transition from wide rifting towards narrow rifting with a pronounced polarity towards the rift center is associated with the advective growth of a thermal perturbation in the mantle lithosphere.

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“…(3) The geophysical signatures of the main lithospheric faults and shear zones responsible for mantle unroofing are strong seismic reflectors, the most famous of them being the S reflector of the Armorican and Galicia margins (De Charpal et al 1978;Le Pichon & Barbier 1987;Hoffmann & Reston 1992;Sibuet 1992;Krawczyk & Reston 1995;Reston et al 1996), named H in the Iberia Abyssal Plain Krawczyk et al 1996;Manatschal et al 2001). The geological signature of the tectonic shearing and exhumation of subcrustal mantle is the foliation and brecciation of the peridotite and intruded gabbro, caused by deformation at falling temperature and decreasing pressure (Girardeau et al , 1998(Girardeau et al , 1999Kornprobst & Tabit 1988;Beslier et al 1990Beslier et al , 1996Cornen et al 1996a,b).…”

mentioning

confidence: 99%

Non-volcanic rifted margins, continental break-up and the onset of sea-floor spreading: some outstanding questions

Boillot

Froitzheim

2001

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During the last 20 years, regional studies on the West Iberia margin and on the former margins of the Tethys have considerably advanced the understanding of processes related to continental break-up and the onset of sea-floor spreading. However, some questions remain outstanding. To tentatively answer these, a coherent interpretation of available data is proposed, based on the detachment fault concept applied to the continental as well as the oceanic lithosphere, and on the hypothesis of a multi-staged rifting process. The interpretation addresses the nature of the lower crust beneath non-volcanic passive margins, the origin of ophicalcites, the probable time gap between syn-or post-rift crystallization of gabbros and extrusion of basalts on the sea floor, and the significance of dipping reflectors within oceanic lithosphere adjacent to non-volcanic passive margins. The interpretation also considers the symmetry v. asymmetry of continental rifting and break-up, the location of the ocean-continent boundary, and the possible association of magnetic quiet zones with ultramafic sea floor (serpentinized peridotite) bordering non-volcanic passive margins.

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Nature of the S reflector beneath the Galicia Banks rifted margin: Preliminary results from prestack depth migration

Cited by 49 publications

References 0 publications

Continent–ocean-transitions: Review, and a new tectono-magmatic model of the Vøring Plateau, NE Atlantic

Continent–ocean-transitions: Review, and a new tectono-magmatic model of the Vøring Plateau, NE Atlantic

Control of rheological stratification on rifting geometry: a symmetric model resolving the upper plate paradox

Non-volcanic rifted margins, continental break-up and the onset of sea-floor spreading: some outstanding questions

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