Structural Analysis of the Volcano- sedimentary Rocks in Tafresh Area, Evidence for Transpression Tectonic in Uroumieh- Dokhtar Volcanic Belt

Category Tectonic & Seismotectonic
Group GSI.IR
Location 21th symposium on geosciences
Holding Date 24 May 2008

      More than three thousand meters thickness is estimated to the volcano-sedimentary sequence exposed in the Tafresh area (about 280km southwest of Tehran). This volcanic sequence consists of three continental margin volcanic units inter-bedded with two distinct green marine volcanic rocks. Two sets of dykes cut these rocks. The first are Eocene age dacite-andesite dykes and the second are Neogene's aged andesite-basaltic dykes. Three structural sub-zones are made by two major faults of Ezaldin fault in north and Tafresh fault in south. The northern fault moderately dips to the northeast, thrust Eocene rocks of the northern part over the Neogene's sediments in the central sub-zone, in contrast, the southern fault with the same strike but the opposite dip-direction thrust the Eocene volcanic sequence of the southern part over the central sub-zone. Structural analysis of the thrust faults; folds and dyke orientations reveal a transpression tectonic event in this part of the Uroumieh-Dokhtar volcanic belt.

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