Coupled phengite 40Ar–39Ar geochronology andthermobarometry: P-T-t evolution of AndrosIsland (Cyclades, Greece) - Archive ouverte HAL Access content directly
Journal Articles Geological Magazine Year : 2015

Coupled phengite 40Ar–39Ar geochronology andthermobarometry: P-T-t evolution of AndrosIsland (Cyclades, Greece)

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Abstract

Andros is a key island for understanding both the timing of high-pressure–low-temperature(HP-LT) metamorphism and the dynamics of crustal-scale detachment systems exhuming high-gradeunits in the Cyclades (Greece). Using phengite 40Ar–39Ar geochronology coupled with thermobarometry,as well as data from literature, we constrain the pressure–temperature–time (P-T-t) paths of theMakrotantalon and Attic–Cycladic Blueschist units on Andros. Peak conditions of the HP-LT episodein the Makrotantalon unit are 550 °C and 18.5 kbar, dated at 116 Ma. We correlate this episode withEarly Cretaceous blueschist facies metamorphism recognized in the Pelagonian zone of continentalGreece. This is a new argument favouring a Pelagonian origin for the Makrotantalon unit. In the Attic–Cycladic Blueschist unit, the P-T-t path is characterized by: (1) exhumation after peak conditions inHP-LT conditions between 55 and 35 Ma; (2) isobaric heating at 7 kbar until 30 Ma; and (3) isothermaldecompression until 21 Ma. This thermal evolution and timing are similar to those of the neighbouringTinos Island, emphasizing major thermal re-equilibration at the transition between stable and retreatingsubduction. Modifications of the crustal thermal state played a major role in the evolution of the NorthCycladic Detachment System, below which Andros HP-LT units were exhumed.

Dates and versions

insu-01114909 , version 1 (10-02-2015)

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Benjamin Huet, Loic Labrousse, Patrick Monié, Benjamin Malvoisin, Laurent Jolivet. Coupled phengite 40Ar–39Ar geochronology andthermobarometry: P-T-t evolution of AndrosIsland (Cyclades, Greece). Geological Magazine, 2015, 152 (4), pp.711-727. ⟨10.1017/S0016756814000661⟩. ⟨insu-01114909⟩
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