Volcanic Margin Concepts

Eldholm, Olav; Skogseid, Jakob; Planke, Sverre; Gladczenko, Tadeusz P.

doi:10.1007/978-94-011-0043-4_1

Cited by 74 publications

(58 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A seaward thickening wedge has been drilled in the study area in well A-C1 and found to consist of mainly basaltic lavas (Gerrard and Smith, 1982). This seaward thickening wedge has been interpreted as corresponding to the coeval postulated seaward dipping reflectors, and to represent extensive basaltic volcanism during the rifting phase of continental break-up (Hinz, 1981;Eldholm et al, 1995). Along the Springbok seismic refraction profile, nearby the Namibian/South African border, a high velocity body (> 7 km/s) is present in the lower crust below this seaward dipping wedge.…”

Section: Discussionmentioning

confidence: 96%

Crustal structure beneath the Orange Basin, South Africa

Hirsch

Scheck‐Wenderoth

Paton

et al. 2007

South African Journal of Geology

View full text Add to dashboard Cite

Although the development of passive margins has been extensively studied over a number of decades, significant questions remain on how mantle and crustal dynamics interact to generate the observed margin geometries. Here, we investigate the Orange Basin, located on the south-west African continental margin. The basin fill is considered to comprise a classic rift-drift passive margin sequence recording the break-up of Gondwana and subsequent opening of the South Atlantic Ocean. Based on interpreted seismic reflection data, a 3D geological model was first constructed. Subsequently, an isostatic calculation (Airy´s model) using a homogeneous middle and lower crust was applied to this geological model to determine the position of the Moho for an isostatically balanced system. Isostatic sensitivity tests were applied to the model, and their gravity response were validated against different crustal structures for the basin.The best-fit model requires dense, presumably mafic material, in the middle and lower crust beneath the basin and an abrupt change to less dense material near the coast to reproduce the observed gravity field.

show abstract

Section: Discussionmentioning

confidence: 96%

Crustal structure beneath the Orange Basin, South Africa

Hirsch

Scheck‐Wenderoth

Paton

et al. 2007

South African Journal of Geology

View full text Add to dashboard Cite

show abstract

“…Most authors envisage that melt is generated rapidly by adiabatic decompression of a rising mantle plume. The quantity of melt depends on the amount of lithospheric extension, subtle temperature increases (50±1008C) in the asthenosphere, thickness of lithosphere before rifting, and the duration of rifting (Bown & White, 1994;Eldholm et al, 1995). Most signi®cantly, the subsidence produced by lithospheric extension alone (McKenzie, 1978) is o set along volcanic margins mainly by: (1) addition to the crust of igneous material produced by decompression and (2) dynamic support by the hot, low-density mantle plume (White & McKenzie, 1989).…”

Section: Large Igneous Provinces and Mantle Plumesmentioning

confidence: 99%

Role of subaerial volcanic rocks and mantle plumes in creation of South Atlantic margins: implications for salt tectonics and source rocks

Jackson¹,

Cramez

Fonck

2000

Marine and Petroleum Geology

174

147

View full text Add to dashboard Cite

Seaward-dipping re¯ectors (SDRs) represent¯ood basalts rapidly extruded during either rifting or initially subaerial sea-¯oor spreading. Evaporites can form on this basaltic proto-oceanic crust, as in the Afar Triangle today. Evidence for SDRs in South Atlantic deep-water regions comes from proximity to the uniquely large ParanaÂ ±Etendeka volcanic province onshore, the Tristan and Gough hot spots, drilled volcanic rocks, and seismic pro®les showing SDR provinces more than 100 km wide, as much as 7 km thick, and thousands of kilometers long. SDRs are clearest adjoining the Aptian salt basins. However, we speculate that SDRs are also present but seismically obscured below the salt basins. We argue that the conjugate Aptian salt basins are post-breakup, not pre-breakup; they were separated from the start by a mid-oceanic ridge; distal salt accumulated on proto-oceanic crust, not rift basins. This hypothesis is supported by: seismic stratigraphy and structure; magnetic anomalies; plate reconstructions; and hydrothermal potash evaporites. An important implication for exploration is that thick basalts, rather than rift-age source rocks, may underlie distal parts of the salt basins. 7

show abstract

“…Volcanic rifted margins are characterised by massive occurrences of extrusive volcanism and intrusive magmatism formed during the rupture of the continental lithosphere and breakup (Hinz, 1981;Mutter et al, 1982;Roberts et al, 1984;White and McKenzie, 1989;Holbrook and Kelemen, 1993;Eldholm et al, 1995). Recent reviews illustrate the wide distribution of such margins that may represent 75-90% of the global continental passive margins (Eldholm et al, 2000;Menzies et al, 2002).…”

Section: Introduction and Geological Settingmentioning

confidence: 99%