Burg, J. 2012.   Rhodope: From Mesozoic convergence to Cenozoic extension. Review of petro-structural data in the geochronological frame. In: (Ed.) Emmanuel Skourtsos, and Gordon S. Lister, The Geology of Greece, Journal of the Virtual Explorer, Electronic Edition, ISSN 1441-8142, volume 42, paper 1.

Rhodope: From Mesozoic convergence to Cenozoic extension. Review of petro-structural data in the geochronological frame

Jean-Pierre Burg

Geologisches Institut, ETH and University Zurich , Sonnegstrasse 5, CH-8092, Zürich, Suisse. <jean-pierre.burg@erdw.ethz.ch>


Mylonitic gneisses of the Bulgarian and Greek Rhodope were deformed under amphibolite-facies conditions of medium pressure type metamorphism. The kinematic information contained on the strain regime and histories of these gneisses shows that ductile, shear-deformation occurred during development of a nappe complex. The nappe complex is characterised by south to southwestward (forelandward) piling-up and both coeval and subsequent extension. Different lithologies, deformation and metamorphic histories discriminate lower (footwall) and upper (hangingwall) continental terranes that define a crustal-scale duplex. Ultrahigh-Pressure metamorphic rocks, eclogites, ophiolitic and magmatic arc protoliths are found in various units of the crustal-scale duplex structure. These rocks delineate a suture zone between the hanging wall and footwall continental units. Synmetamorphic suturing and thrusting imply crustal thickening during the Cretaceous, which implies that the Rhodope massif is a complex of synmetamorphic nappes stacked in a Tethyan active margin environment. The two blocks involved in the collision are the Moesian part of the European continent to the north, and the Lower-Rhodope Terrane to the south, which was a migrating block detached from Pangea during breakup times of this supercontinent.

Regional inversions of synmetamorphic sense-of-shear indicate that exhumation tectonics began in Cretaceous times, possibly linked to upward-forward expulsion of low density arc and continental rocks. A Late Eocene marine transgression separates the early, late-orogenic extension/exhumation phase from another extension event accompanied by a major thermal and magmatic event and followed by the Miocene Aegean extension responsible for late grabens over the Rhodope Massif.

Keywords: Alpine chains, regional synthesis, thrust and exhumation tectonics