HR: 1340h
AN: V13A-1137 INVITED    [Abstracts]
TI: Geodynamic evolution of an UHP Suture Zone in the Greek Rhodope
AU: * Krenn, K
EM: kurt.krenn@ uni-graz.at
AF: Institute of Earth Sciences, Dept. of Mineralogy and Petrology, Karl-Franzens-University of Graz, Universitätsplatz 2, Graz, 8010, Austria
AU: Bauer, C
EM: christoph.bauer@uni-graz.at
AF: Institute of Earth Sciences, Dept. of Mineralogy and Petrology, Karl-Franzens-University of Graz, Universitätsplatz 2, Graz, 8010, Austria
AU: Proyer, A
EM: alexander.proyer@uni-graz.at
AF: Institute of Earth Sciences, Dept. of Mineralogy and Petrology, Karl-Franzens-University of Graz, Universitätsplatz 2, Graz, 8010, Austria
AU: Hoinkes, G
EM: georg.hoinkes@uni-graz.at
AF: Institute of Earth Sciences, Dept. of Mineralogy and Petrology, Karl-Franzens-University of Graz, Universitätsplatz 2, Graz, 8010, Austria
AB: Detailed mapping of Alpine suture zone areas in the Greek Rhodope Metamorphic Complex and characterisation in terms of structures, petrology and geochronology reveal a tectonic wedge geometry with synmetamorphic SW shear at the base and NE shear on-top. These areas define a suture zone (Rhodope Suture Zone, RSZ) which developed between two continental plates of Variscan and Late Jurassic age (Turpaud & Reischmann 2005). It is subdivided into the Lower Rhodope Suture Zone (LRSZ) with material of mainly continental provenance and the Upper Rhodope Suture Zone (URSZ) with constituents of continental and oceanic origin. Both subunits contain microdiamond-bearing metapelites (Perraki et al. 2006) and record metamorphic stages starting from UHP in the Early/Middle Jurassic (≥ 180 Ma) to amphibolite facies conditions in the Late Cretaceous (≤ 79 Ma) (Bauer et al. 2007). The rocks of the LRSZ underwent uniaxial stretch during upward movements to lower crustal levels (≤ 12 kbar; 650°C) at ca. 144 Ma forming L\ggS tectonites (deformation stage D1). The rocks of the URSZ experienced delayed exhumation and static annealing near 16 kbar and ~800°C at ca. 160 Ma. For both subunits subsequent exhumation was controlled by NE-SW shear along the Rhodope Normal Fault (RNF), which kinematically divides the two subunits of the RSZ (deformation stage D2). The duration of activity along the RNF is constrained by the formation of large-scale folds which formed during shear-partitioning (deformation stage D3) at conditions of <8 kbar and 650°C. D3 probably emerged along a discrete steep fault (Avren Fault in Bulgaria), re-orients earlier high-grade structures and separates central and eastern parts of the Rhodope Metamorphic Complex. D3 characterizes the Mid- to Late Cretaceous amphibolite/greenschist facies thrust tectonics in the Aegean region. N-vergent thrusting of low-grade Mesozoic schists including Jurassic ophiolites east of the fault is coeval with SSW vergent nappe consolidation in the central and western region. The source rocks of the RSZ are proposed to originate from a Variscan microcontinent and an ocean basin to the north. This ocean is interpreted as the easternmost branch of the Triassic/Jurassic Neotethyan ocean (Meliata ocean – eo-Alpine phase), which underwent subduction and metamorphism together with the microcontinent since the Early Jurassic. REFERENCES
BAUER, C., RUBATTO, D., KRENN, K., PROYER, A. & HOINKES, G. 2007. A zircon study from the Rhodope Metamorphic Complex, N-Greece: Time record of a multistage evolution. Lithos, in press.
PERRAKI, M., PROYER, A., MPOSKOS, E., KAINDL, R. & HOINKES, G. 2006. Raman micro-spectroscopy on DIAMOND, graphite and other carbon polymorphs from the ultrahigh-pressure metamorphic Kimi Complex of the Rhodope Metamorphic Province, NE Greece. Earth and Planetary Science Letters 241, 672-685.
TURPAUD, P. & REISCHMANN, T. 2005. Relationships between crustal blocks and UHP relicts, an example from Northern Greece. Geophysical Research Abstracts 0453, 7.
DE: 1115 Radioisotope geochronology
DE: 3651 Thermobarometry
DE: 8011 Kinematics of crustal and mantle deformation
DE: 8104 Continental margins: convergent
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting