History of Magmatism and Crustal Evolution in the Central Greater Caucasus Mountain Range, Southern U.S.S.R.

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The Greater Caucasus Mountain Range is a rapidly rising mountain belt driven by the collision of the Iranian-Turkish and Arabian continental blocks with the Russian craton. In cooperation with Soviet colleagues a number of problems bearing on the tectonic evolution of the northern Tethys ocean margin, the involvement of the Russian craton in active margin processes have been identified. These have significance for widely- applicable processes of intra- sialic rifting, the irregular response to deformation of irregular shapes of collisional blocks and in the recycling of compositionally heterogeneous basement nappes into new sialic crust by superposed batholithic magmatism. The work will focus on the structural setting and isotope geochemistry of the Chegem River Caldera and related rocks and possible relationships to the transcaucasus structural zone, U/Pb zircons geochronology of previously collected samples from the Bechasin, Fore Range and Main Range basement zones and the age and tectonic setting of the Kasbek diabase belt and related intrusions along the southern boundary zone. Results are expected to increase knowledge of sialic crustal genesis, mesozoic intra-sialic rifting and the neotectonic regime of this area.