Late Cretaceous-to-Pliocene thermo-tectonic history of Pelagonia (northern Greece) from zircon and apatite fission-track ages

Schenker, Filippo and Fellin, Maria Giuditta and Burg, Jean-Pierre (2014) Late Cretaceous-to-Pliocene thermo-tectonic history of Pelagonia (northern Greece) from zircon and apatite fission-track ages. In: Abstract Volume, 12th Swiss Geoscience Meeting 12th Swiss Geoscience Meeting, Fribourg, Switzerland.

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Abstract

The Pelagonian zone, between the External Hellenides/Cyclades to the west and the Axios/Vardar/Almopia (AVA) zone and Rhodope to the east, was involved in the late Early Cretaceous and in the Late Cretaceous-Eocene compressional events. Timing and spatial distribution of these events have remained so far partly unresolved. We will present new and published zircon (ZFT) and apatite (AFT) fission-track ages integrated with new field observations to constrain their thermal overprint. The Early Cretaceous (130-110 Ma) thrust system of the Pelagonian basement and AVA zone was covered on a 99-to-80 Ma unconformity by marine sediments, whose deposition continued until ca. 66 Ma (documented by Globotruncanae). The metamorphic imbricates of the western AVA zone cooled below 240 °C between 102 and 93.5-90 Ma and the ones of northern Pelagonia, eastern AVA zone and western Rhodope between 80 and ca. 68 Ma. This regional ca. 30 Ma long cooling and subsidence was followed by the reactivation of thrusting that caused abrupt and rapid cooling and erosion of the Pelagonian basement at ca. 68 Ma, as documented by clasts in ca. 66 Ma old marine sediments with detrital ZFT ages clustering at ca. 68 Ma. In the Paleocene-Eocene thrusting migrated in the External Hellenides and cooled western Pelagonia below ca. 120 °C in the hanging wall of its sole thrust. Subsequently in central-eastern Pelagonia, ZFT and AFT ages attested rapid and uniform cooling between 24 and 16 Ma in the footwall of a major extensional fault. Extension started even earlier at 32.7 Ma in the western AVA zone according to reset AFT ages within normal faults. A final post-7 Ma rapid cooling is inferred by inverse modeling of AFT lengths along a E-W normal fault zone cutting Pliocene-to-recent sediments.

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