Timing of the Amorgos detachment system and implications for detachment faulting in the southern Aegean Sea, Greece
Uwe Ring, Stuart N. Thomson, Gideon Rosenbaum, 2009. "Timing of the Amorgos detachment system and implications for detachment faulting in the southern Aegean Sea, Greece", Extending a Continent: Architecture, Rheology and Heat Budget, U. Ring, B. Wernicke
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We present apatite and zircon fission-track (AFT and ZFT) ages from the Amorgos detachment system in the Aegean Sea, Greece. The Amorgos detachment system consists of a basal and an upper detachment. The lower Amorgos detachment occupies the same tectonic position as the regionally important large-magnitude Cretan detachment and therefore can provide improved constraints on the evolution of the latter. AFT ages from the footwalls of both detachments show that detachment-related cooling occurred in the early Miocene, coeval with an important phase of cooling in the footwall of the Cretan detachment on Crete. We interpret the footwall AFT ages to indicate an early Miocene age of movement on the Amorgos detachments, essentially simultaneously with slip on the Cretan detachment. ZFT ages from rocks above the lower Amorgos detachment are not reset indicating that metamorphic temperatures during the Tertiary Hellenic orogeny did not exceed c. 300 °C significantly. We discuss a model in which top-to-the-north movement on the Cretan/Amorgos detachment commenced in the early Miocene. Soon after the inception of the Cretan/Amorgos detachment, top-to-the-south movement on the South Cyclades shear zone deformed the latter and brought the Amorgos detachment into a higher crustal position.
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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.