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Tectonic response of the central Chilean margin (35-38 degrees S) to the collision and subduction of heterogeneous oceanic crust: a thermochronological study

Spikings, R. and Dungan, M. and Foeken, J. and Carter, Andrew and Page, L. and Stuart, F. (2008) Tectonic response of the central Chilean margin (35-38 degrees S) to the collision and subduction of heterogeneous oceanic crust: a thermochronological study. Journal of the Geological Society 165 (5), pp. 941-953. ISSN 0016-7649.

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Official URL: http://dx.doi.org/10.1144/0016-76492007-115

Abstract

Along-strike geological segmentation in the Andean chain has been recognized at various scales and is usually attributed to changes in plate motion vectors, as well as the upper-plate expression of differing subducted slab age, strength and composition. We present new multi-phase 40Ar/39Ar, apatite fission-track and zircon and apatite (U–Th)/He data from a north–south-oriented traverse between 35 and 38°S along the Principal Andean Cordillera of Chile that reveal (1) rapid cooling at 18 and 15 Ma, which can be attributed to both thermal relaxation following magmatic intrusion and regional-scale exhumation, and (2) along-strike differences in the extent of exhumation since 7.5 Ma that may be a consequence of the subduction of the Juan Fernandez Ridge above the flat-slab segment at 32°, since 10 Ma. A comparison of the response of the South American Plate to the collision of the Carnegie, Nazca and Juan Fernandez ridges suggests that slab flattening is not the dominant driving force that exhumes the upper plate in these settings. Rather, the extent of exhumation is controlled by pre-existing structural weaknesses, the time duration of the dynamically supported topography, and climate.

Item Type: Article
School or Research Centre: Birkbeck Schools and Research Centres > School of Science > Earth and Planetary Sciences
Depositing User: Administrator
Date Deposited: 10 Feb 2011 09:43
Last Modified: 17 Apr 2013 12:18
URI: http://eprints.bbk.ac.uk/id/eprint/1752

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