Upper Cretaceous exhumation of the western Rhodope Metamorphic Province (Chalkidiki Peninsula, northern Greece)

Abstract

The Vertiskos Unit of northern Greece is an elongated basement belt with a complex poly-metamorphic history. It extends from Greece (Chalkidiki peninsula), to the south, up to Serbia, in the north, and arguably represents the westernmost part of the Rhodope Metamorphic Province (northern Greece to southern Bulgaria). The Vertiskos Unit experienced a medium pressure lower amphibolite-facies metamorphic overprint during the Alpine Orogeny. The available medium-temperature geochronology implies that it remained at temperature of approximately 300°C (or slightly higher) during Lower Cretaceous. In order to constrain its post-Lower Cretaceous thermal history, until near-surface exposure, we applied apatite fission track analysis. The central ages obtained range from 68.5 ± 3.8 to 46.6 ± 3.6 Ma (uppermost Cretaceous to Middle Eocene) and mean track lengths between 13 and 13.5 μm. We applied two inverse thermal modeling approaches using either each sample independently (high degree of freedom in the thermal history, better data fit) or all samples together interpreting them as a vertical profile (simpler thermal history, worse data fit). Irrespective of the modeling approach, we conclude that the bulk thermal history of the Vertiskos Unit crosses the high-temperature limit of the apatite partial annealing zone by the uppermost Cretaceous and reaches near-surface conditions as early as lower/middle Eocene. These results contrast with the thermal history of the other domains of the Rhodope Metamorphic Province further east (namely the Southern Rhodope Core Complex and the Northern Rhodope Complex) and establish the Vertiskos basement complex as the oldest exhumed coherent basement fragment of the Rhodope Metamorphic Province and Greece.

Metamorphic conditions and structural evolution of the Kesebir-Kardamos dome: Rhodope metamorphic complex (Greece-Bulgaria)

“…In the southern parts of the KKD dome, the age of the oldest unconformable sediments is Lutetian (48-41Ma; Caracciolo et al 2012). Finally, low-temperature thermochronology data over the western Rhodope suggest cooling below 240ºC at 72Ma (Kydonakis et al 2014;Kounov et al 2015;Schenker et al 2015). Similar correlations between metamorphic ages and crystallization ages of plutons can also be observed in central Rhodope (Fig.…”

Polyphase evolution of Pelagonia (northern Greece) revealed by geological and fission-track data

“…The few data in the AVAZ are 60-47 Ma (Most et al, 2001;Most, 2003). The western Rhodope also yielded AFT ages from 68 to 47 Ma (Kydonakis et al, 2014).…”

Kinematic reconstructions and magmatic evolution illuminating crustal and mantle dynamics of the eastern Mediterranean region since the late Cretaceous

“…the Vertiskos unit) has stayed in near-surface conditions since the early-middle Eocene (figures 3 and 6) [Sokoutis et al, 1993;Brun and Sokoutis, 2007;Wüthrich, 2009;Kydonakis et al, 2014]. Based on paleomagnetism [Kondopoulou and Westphal, 1986] and on the curvature of the stretching lineations in the MCC, Brun and Sokoutis [2007] hypothesize an ~30° clockwise rotation of the hanging wall of the Kerdylion detachment (including the Chalkidiki Peninsula) with the major part of the rotation occurring in the final stage of exhumation of the south Rhodope core complex after 15 Ma [van Hinsbergen et al, 2008].…”