Cenozoic tectonic evolution of Naxos Island through a multi-faceted approach of fission-track analysis
Published:January 01, 2009
Diane Seward, Olivier Vanderhaeghe, Luc Siebenaller, Stuart Thomson, Christian Hibsch, Anatol Zingg, Patrick Holzner, Uwe Ring, Stephanie Duchêne, 2009. "Cenozoic tectonic evolution of Naxos Island through a multi-faceted approach of fission-track analysis", Extending a Continent: Architecture, Rheology and Heat Budget, U. Ring, B. Wernicke
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New zircon and apatite fission-track ages obtained on samples from all lithotectonic units exposed on Naxos Island are presented. Zircon ages of the exhumed metamorphic rocks range from 25.2 to 9.3 Ma and from 13.0 to 6.4 Ma for apatite. Zircon track-length analysis distinguishes partial overprinting of an earlier event (M1) in the south. Northwards no overprint is seen and the ages there represent rapid exhumation since c. 12 Ma. Both zircon and apatite ages are slightly older toward the north of the island probably due to variation of the geotherm in the proximity of the fault.
Zircon fission-track ages of the granodiorite range from 13.7 to 12.2 Ma are statistically identical to previously determined U–Pb ages. Apatite fission-track ages however, yield a younging trend from south to north from 12.9 to 9.0 Ma. This could be due to differential depth of emplacement and/or to differential exhumation during tectonic unroofing by a top-to-the north detachment.
Fission-track ages on detrital grains in Lower Miocene sediments indicate a source not identified within the present outcropping rocks of Naxos. Ages on boulders and grains in the Middle to Upper Miocene sediments point to rapid erosion until about 8.5–7 Ma.
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Extending a Continent: Architecture, Rheology and Heat Budget
Over the last three decades, there has been a growing appreciation of the role of extensional tectonics in convergent orogens. The opening contribution to this book, by Brian Wernicke, provides a flavour of how this ‘detachment era’ has changed our views on tectonometamorphic relationships in mountain belts. This introduction provides a historical account on how our views on large-scale tectonic contacts in mountain belts have changed over the years. Wernicke concludes that controversy still persists over the existence and mechanics of slip on shallowly dipping extensional detachments, although incontrovertible field evidence indicates that slip on shallowly dipping extensional faults occurs in nature. Other papers in the volume provide a mix of new, innovative and controversial ideas that may help to solve the mechanical paradox on slip on shallowly dipping extensional detachments and quantitative case studies from New Zealand, the Aegean extensional province, the Alps and Finland.