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Tectonics and sedimentary environment of the North Scotia Ridge region revealed by side-scan sonar

Cunningham, A. P.; Barker, P. F.; Tomlinson, J. S.. 1998 Tectonics and sedimentary environment of the North Scotia Ridge region revealed by side-scan sonar. Journal of the Geological Society, 155 (6). 941-956. 10.1144/gsjgs.155.6.0941

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Abstract/Summary

The North Scotia Ridge is a series of islands and submarine ridges extending 2000 km from Tierra del Fuego to South Georgia in the western South Atlantic. The ridge forms the elevated northern tectonic margin of the Scotia Sea, and accommodates E–W sinistral strike-slip motion at the South American–Scotia plate boundary. Existing studies have shown that the northern flank of the North Scotia Ridge is a large and continuous accretionary prism, formed during presumed mid–late Cenozoic N–S convergence. In this study, we present long-range side-scan sonar (GLORIA) images and seismic reflection profiles which show the structural style of the accretionary prism for the first time. The youngest accreted sediments show a uniform fabric of initial deformation (symmetric–gently asymmetric folds of 1–4 km wavelength), which has been subsequently disrupted at shallower depths by additional shortening and uplift. Between 52 degrees 45 minutes W and 50 degrees 30 minutes W, the deformation front is exposed at the sea floor, and the Falkland Trough retains the appearance of an active convergent margin. Elsewhere, however, the deformation front is buried beneath younger, undeformed drift sediments indicating that convergence has ceased. GLORIA sonographs also show geological features consistent with current-control of sedimentation, nondeposition, and erosion beneath the Antarctic Circumpolar Current. In particular, this study describes current-influenced sedimentation in the Falkland Trough, and steep-sided, eroded depressions and diffuse slope-parallel fabric on the elevated Falkland Plateau.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1144/gsjgs.155.6.0941
Programmes: BAS Programmes > Pre 2000 programme
ISSN: 0016-7649
Additional Keywords: GLORIA, Scotia Ridge, South Atlantic, accretionary wedges
Date made live: 20 Nov 2013 14:12 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/503950

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