The 3D geometry of the Naxos detachment fault and the three-dimensional tectonic architecture of the Naxos metamorphic core complex, Aegean Sea, Greece

Autor: Reuben J. Hansman, Uwe Ring, Henrik Linnros
Rok vydání: 2018
Předmět:
Zdroj: International Journal of Earth Sciences. 108:287-300
ISSN: 1437-3262
1437-3254
Popis: We reconstruct the three-dimensional (3D) geometry of the Naxos detachment fault and quantify E–W shortening associated with strong N–S extensional deformation. In addition, 3D reconstruction of the detachment indicates how it interacted with the underlying metamorphic sequence, as well as a set of concentric metamorphic isograds that formed during extensional deformation. For doing so, we used the software MOVE™ (Midland Valley Ltd.) to develop a 3D model of the Naxos metamorphic core complex (NCC) and the Naxos detachment fault. The model is constrained by structural data, metamorphic isograds, and fission-track ages from the footwall of the NCC. Our analysis shows that greater minimum amounts of E–W shortening correlate with higher metamorphic grade, ranging from 6 to 10% outside the migmatite dome and up to 17% within the migmatite dome. The metamorphic isograds around the migmatite dome are less intensely folded by E–W shortening than the lithologic layering. We conclude that this is because the isograd surfaces “froze-in” after folding had already started. Our model indicates that the isograds are cut by the brittle detachment, demonstrating that the final stages of top-to-the-NNE extension outlasted the formation of the metamorphic dome and the isograds. Despite some limitations of the 3D model, the outlined geometric reconstruction of a major extensional fault system in the central Aegean highlights: (1) the interplay between large-scale extension and temperature-dependant shortening perpendicular to the extension direction, (2) the evolution of metamorphism and migmatization, (3) the formation of metamorphic isograds, and (4) granitoid intrusions during extension and exhumation.
Databáze: OpenAIRE
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