Journal articles
First-report on Mesozoic eclogite-facies metamorphism preceding Barrovian overprint from the western Rhodope (Chalkidiki, northern Greece)
Abstract : The Chalkidiki block in Northern Greece represents the southwesternmost piece of the
ultrahigh-pressure Rhodope and has played an important role in the evolution of the North
Aegean. The eastern part of the Chalkidiki block is a basement complex (Vertiskos Unit) that
is made largely of Palaeozoic granitoids and clastic sediments metamorphosed during the
Mesozoic. This basement is traditionally considered as part of the Rhodopean hanging-wall,
an assignment mainly supported by the absence of high-pressure mineral indicators and the
presence of a regional medium-pressure/medium-temperature amphibolite-facies Barrovian
metamorphic imprint. Toward the west, the basement is juxtaposed with meta-sedimentary
(Circum-Rhodope belt) and arc units (Chortiatis Magmatic Suite) that carry evidence of a
Mesozoic high-pressure/low-temperature event. In this study, garnet-staurolite-mica schists
from the eastern part of the basement were examined by means of micro-textures, mineral
chemistry and isochemical phase-diagram sections in the system NCKFMASHMn(Ti)
[Na2O-CaO-K2O-FeO-MgO-Al2O3-SiO2-H2O-MnO-(TiO2)]. The schists represent former
Mesozoic sedimentary sequences deposited on the Palaeozoic basement. We document the
presence of a relict eclogite-facies mineral assemblage (garnet + chloritoid + phengite +
rutile) in an amphibolite-facies matrix composed of garnet + staurolite + phengite ± kyanite.
Model results suggest the existence of a high-pressure/medium-temperature metamorphic
event (1.9GPa / 520°C) that preceded regional re-equilibration at medium-pressure/mediumtemperature
conditions (1.2GPa / 620°C). Clearly, the eastern part of the Chalkidiki block
(basement complex) retains memory of an as yet unidentified Mesozoic eclogitic
metamorphic event that was largely erased by the later Barrovian overprint. In the light of our
findings, the basement complex of the Chalkidiki block shares a common tectonometamorphic
evolution with both the high-pressure units to the west, and the high-grade
Rhodopean gneisses further to the northeast. Our results are consequential for the geodynamic reconstruction of the Rhodope since they require participation of the Chalkidiki
block to the well-established Mesozoic subduction system.
https://hal-insu.archives-ouvertes.fr/insu-01117877
Contributor : Isabelle Dubigeon <>
Submitted on : Wednesday, February 18, 2015 - 2:02:36 PM
Last modification on : Thursday, January 14, 2021 - 11:45:59 AM
Long-term archiving on: : Sunday, April 16, 2017 - 9:58:01 AM
Contributor : Isabelle Dubigeon <>
Submitted on : Wednesday, February 18, 2015 - 2:02:36 PM
Last modification on : Thursday, January 14, 2021 - 11:45:59 AM
Long-term archiving on: : Sunday, April 16, 2017 - 9:58:01 AM
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Kydonakis-lithos-2015.pdf
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