HR: 1340h
AN: V43B-1367    [Abstracts]
TI: Significance of E. Paleozoic Paleo-Tethyan Ophiolites in the Balkan Terrane and the Greater Caucasus for the Cadomian-Hercynian Continental Growth of Southern Europe
AU: * Zakariadze, G S
EM: gurzak@geokhi.ru
AF: Russian Academy of Sciences, Vernadsky Institute of Geochemistry and Analytical Chemistry, Moscow, 119991, Russian Federation
AU: Karamata, S O
EM: inga@eunet.yu
AF: Serbian Academy of Sciences and Arts, Knez Mihailova 35, Belgrade, YU-11000, Yugoslavia
AU: Dilek, Y
EM: dileky@muohio.edu
AF: Miami University, Dept. of Geology, Oxford, OH 45056, United States
AU: three others, a
EM: tamara@geoksc.apatity.ru, korik@igem.ru, sergeev@mail.wplus.net
AF: Russian Academy of Sciences, Geol. Inst. of Kola Branch, Apatity, 111000, Russian Federation
AB: New geochronological & geochemical data from dismembered E. Paleozoic ophiolites in the Balkan Terrane (Serbia) & the Greater Caucasus (Russian Federation) link these remnants of the Paleo-Tethyan oceanic crust to a series of events associated with the Cadomian and Hercynian evolution of S. Europe. The Balkan-South Carpathian ophiolite belt (BSCOB) WSW of the Moesian platform is part of the South European suture zone (SESZ) & includes the Deli Jovan massif (DJM) composed of ultramafic mantle restites, ultrabasic & basic cumulates, gabbros, diabasic dikes and basalts. The analyzed gabbros of DJM are high-Al (19-24.5 wt.%) cumulate gabbros-troctolites (Ol_82-89+Cpx_79-87+Pl_77-91) originated from shallow-depth crystallization of low-K (<0.3 wt.%) tholeiitic basaltic melt (T=1050°-1160°). Dike rocks are composed of fine-grained, Cpx-Pl microphyric, high-Mg tholeiitic microgabbro-diabase showing MORB affinities [(La/Sm)_n=0.18-1.31; (La/Yb)_n=0.22-1.35; Th/La=0.073-0.19; Zr/Y=1.60-2.39] derived from depleted mantle source(s). New isotopic ages range between 406±24 Ma and 399.7±5.2 Ma [Sm-Nd isochron age of 406±24 Ma, MSWD=0.71; U-Pb isotope dilution zircon age of 399.7±5.2 Ma; U-Pb SHRIMP zircon age of 405.0±2.6 Ma]. Ophiolitic rocks of the BSCOB continue E into the Paleozoic metamorphic basement of the Istanbul-Zonguldak Unit (IZU) in NW Turkey & the Crystalline Core and the Fore Range Zones of the Greater Caucasus. The metaophiolites in the Greater Caucasus include residual peridotites, ultrabasic & basic cumulates, gabbros, dike complexes, and volcanic rocks with limestones, ranging in age from 490 to 416 Ma. The volcanic sequences in these ophiolites include low-silica (SiO₂=43.94-48.10 wt.%), high-Ti (TiO₂=2.0-3.3 wt.%) and high phosphorus tholeiitic basalts showing slightly enriched T-MORB affinities [(La/Sm)_n=2.98±0.57; (La/Yb)_n=5.72±2.05; (Tb/Yb)_n=1.42±0.62; and (Yb)_MORB=0.97±0.35], and high-silica (SiO₂=47.54-53.94 wt.%), low-Ti (TiO₂=0.46-1.09 wt.%) and low-K tholeiitic basalts, basaltic andesites & andesites, showing suprasubduction zone affinities [(Tb/Yb)_n=1.04±0.34; (Yb)_MORB=0.62±0.28; and negative Nb and Zr anomalies]. The Early Paleozoic ophiolitic rocks within the SESZ along the southern edge of the European Platform (including the Moesian and Scythian platforms) developed during the evolution of the Paleo-Tethyan back-arc basin via seafloor spreading and arc-trench-subduction rollback processes behind the northward drifting peri-Gondwanan terranes (i.e. Transcaucasian massif in Georgia; IZU, Menderes and Armutlu massifs in Turkey; Florina terrane in Greece). They were accreted to the Eurasian continental margin during the Hercynian orogeny. The Cadomian peri- Gondwanan terranes & the SESZ ophiolites subsequently became part of the basement of a Late Paleozoic magmatic arc above a Paleo-Tethyan subduction zone along the southern margin of Europe.
DE: 3621 Mantle processes (1038)
DE: 8103 Continental cratons
DE: 8120 Dynamics of lithosphere and mantle: general (1213)
DE: 8178 Tectonics and magmatism
DE: 8413 Subduction zone processes (1031, 3060, 3613, 8170)
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting