Study of collision-related volcanoes of

Prof Marjorie Wilson ([email protected]), Dr Ivan Savov ([email protected])

Rationale

Little is known about the petrology and geochemistry of Tertiary-Holocene volcanoes of Armenia, which form part of an extensive continental collision-related volcanic province within the Caucasus Mountains extending from through Armenia and into , Iran and Georgia. This is a region with very active crustal-scale faults responsible for triggering large earthquakes. The volcanoes of the Caucasus region have been erupting since the and many are still active. Their position is intimately related to major fault locations, which are associated with the ongoing collision between 3 tectonic plates- Eurasia, Arabia and Africa. This region represents one of the few places on Earth (in addition to the Himalayan orogenic belt in Tibet), where it is possible to study volcanism associated with active continent-continent collision.

Noradus is an andesite cinder cone and is among the many unstudied collision-related volcanoes in the region of Sevan in Armenia.

The Quaternary volcanoes of Armenia (> 500 mapped) form an arc of activity that is associated with numerous small pull apart basins related to regional tectonic movements. Many have never been studied previously, making this a frontier area for research. Improved knowledge of the active volcanism in Armenia will provide a critical contribution to a large interdisciplinary international research project (in which Dr. Savov and Univ. Leeds geochemistry labs are key partners) focused on volcanic hazard assessment in the context of site selection for new nuclear power plant (NPP) constructions in the region.

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Small cindercone in the foothills of Mt.Ararat Holocene lava flow from Porak volcano and Mt.Lesser Ararat volcanoes in E. Turkey. entering the nearby glacial lake, Vardenis Studies of the petrology and geochemistry of Volcanic Ridge, Armenia. small versus large in size structures will

provide clues on understanding the big volume differences of magma erupting at the

surface.

Training

This project will include the construction of a petrological and geochemical synthesis of the magmatism within Armenia, with a focus on the Holocene and Quaternary volcanism. It will involve field mapping and sampling of series of volcanic structures-cinder cones, lava flows and stratovolcanoes,followed by detailed petrographic and textural description of the volcanic rocks and microprobe (EPMA) analysis of the constituent minerals. The student will be trained in the lab for preparing and analyzing samples for bulk-rock major and trace elements and the isotope ratios of Sr-Nd-Pb-B. This project will be in collaboration with scientists from the Carnegie Institution of Washington-DTM (USA), CNR-Pisa (Italy) and Univ. Potsdam (Germany). The geochemical data will be used to develop petrogenetic models for the magmatism and to understand the relationships between magma chemistry and magma volumes, mantle and crustal structure and tectonic setting. References:

Keskin, M., 2003. Magma generation by slab steepening and breakoff beneath a subduction-accretion complex: An alternative model for collision-related volcanism, Geophys. Res. Lett. 30, 24, 8046, doi: 10.1029/2003GL018019;

Karakhanian, A., et al 2002. Holocene-historical volcanism and active faults as natural factors for Armenia and adjacent countries, J. Volcanol. Geotherm. Res. 113, 319-344;

Guo, Z., Wilson, M., Liu, J., Mao, Q., 2006. Post-collisional, potassic and ultrapotassic magmatism of the Northern Tibetan plateau: constraints on characteristics of the mantle source, geodynamic setting and uplift mechanisms, J.Petrology, doi:10.1093/petrology/egl007

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