Animated tectonic reconstruction of the Southern Pacific and alkaline volcanism at its convergent margins since Eocene times

Eagles, Graeme; Gohl, Karsten; Larter, Robert D. ORCID: https://orcid.org/0000-0002-8414-7389. 2009 Animated tectonic reconstruction of the Southern Pacific and alkaline volcanism at its convergent margins since Eocene times. Tectonophysics, 464 (1-4). 21-29. 10.1016/j.tecto.2007.10.005

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Official URL: http://dx.doi.org/10.1016/j.tecto.2007.10.005

Abstract/Summary

An animated reconstruction shows South Pacific plate kinematics, in the reference frame of West Antarctica, between 55 Ma and the present-day. The ocean floor in the region formed due to seafloor spreading between the Antarctic, Pacific, Phoenix and Nazca plates (a plate formed by fragmentation of the Farallon plate early in Oligocene times). The Pacific-Antarctic Ridge remained fairly stable throughout this time, migrating relatively northwestwards, by various mechanisms, behind the rapidly-moving Pacific plate. The Nazca and Phoenix plates also moved quickly, but relatively towards the cast or southeast, and were subducted in these directions beneath the South American and Antarctic plates. Segments of spreading centres forming at the trailing edges of the Nazca and Phoenix plates periodically collided with these subduction zones, resulting in the total destruction of the Nazca Phoenix spreading centre and the partial destruction of the Nazca-Antarctica spreading centre (the Chile Ridge) and Antarctic-Phoenix Ridge, which ceased to operate shortly before its northeasternmost three segments could collide with the Antarctic margin. Following collision of segments of the Chile Ridge, parts of the Antarctic plate underwent subduction at the Chile Trench. After these collisions, slab windows Should have formed beneath both the South American and Antarctic convergent margins, and the animation shows Occurrences of alkaline volcanism that have been, or can newly be, related to them. Further occurrences of alkali basalts, at the margins of the Powell Basin and, more speculatively, James Ross Island, can be related to the formation of a slab window beneath them following the collision of segments of the South America Antarctica spreading centre in the northwest Weddell Sea. (C) 2007 Elsevier B.V. All rights reserved.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1016/j.tecto.2007.10.005
Programmes:	BAS Programmes > Global Science in the Antarctic Context (2005-2009) > Glacial Retreat in Antarctica and Deglaciation of the Earth System
ISSN:	0040-1951
Additional Keywords:	plate kinematics; subduction; slab windows
NORA Subject Terms:	Earth Sciences
Date made live:	25 Oct 2010 13:57 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/10735

Item Type:

Publication - Article

Digital Object Identifier (DOI):

10.1016/j.tecto.2007.10.005

Programmes:

BAS Programmes > Global Science in the Antarctic Context (2005-2009) > Glacial Retreat in Antarctica and Deglaciation of the Earth System

ISSN:

0040-1951

Additional Keywords:

plate kinematics; subduction; slab windows

NORA Subject Terms:

Earth Sciences