Book of Abstracts Oral Presentations EARLY JURASSIC METAMORPHISM IN CENTRAL IRAN: GEODYNAMIC IMPLICATIONS Zanchi, A.1, Zanchetta, S.2, and Javadi, H.3 1,3Department of Earth and Environmental Sciences, Univ. Milano- Bicocca, Milan, Italy 2Geological Survey of Iran, Meraj Boulevard, Teheran, Iran E-mail:
[email protected] Central Iran consists of several terranes, mainly derived from Gondwana and accreted to the Eurasian margin during the Cimmerian orogeny. In its NW part, three metamorphic complexes containing dismembered “ophiolites”, the Anarak, Jandaq and Posht-e-Badam, occur. The age of metamorphism, geodynamic significance, and palaeogeographic provenance of such units are largely debated. The evolution of the Anarak complex is, until now, the best understood among the others. It has been interpreted as an allochthonous crustal fragment belonging to the accretionary belt developed during Carboniferous times on the southern margin of Eurasia. The mechanisms and timing of large-scale deformation during Mesozoic and Cenozoic times that brought the Anarak unit in its present-day position are poorly understood. An undefined Precambrian to early Palaezoic age has been instead inferred for the Posht-e-Badam and Jandaq complexes. The Jandaq complex is divided in two subunits: the Arusan ophiolitic mélange and the Jandaq metamorphic unit. To the north, the complex is in tectonic contact with the Airekan basement, mainly made of Lower Cambrian granites. The ophiolitic mélange consists of serpentinized harzburgites, metagabbros, prasinites and quartzites, the last likely representing metacherts. Minor marbles lenses also occur. The ophiolites display a predominant greenschists facies mineralogical assemblage, with only minor relicts of amphibolite-facies minerals.