Volcanological and Geochemical Features of the Products of Sabalan’s Last Eruption, NW Iran

Abstract

Sabalan volcano is located in the northwest part of Iran and 25km south of Meshkinshahr in the west Alborz-Azerbaijan structural zone. The rocks forming the Sabalan and its eastern and northern slopes are covered with significant amounts of white-gray pyroclastic deposits, which is indicating a very intense explosive activity at the last stage of this huge volcano activity. After conducting field studies and analyzing the results obtained using the mathematical calculations, a Plinian eruption was detected, and the extrapolated volume of the latest pyroclastic fall eruption was estimated 3.24 km3, and the eruption of Sabalan rated a VEI of 5. Also, due to the shape of the isopach curve, the role of wind in dispersing these deposits is from the west to the east. Also based on geochemical data, the Sabalan’s ignimbrite was rhyodacitic with calc-alkaline signatures and the high ratios of Ba/Nb>28 and Ba/Ta>450 are consistent with subduction related zone.

Keywords

• pyroclastic
• plinian
• volcanic explosivity index
• ignimbrite
• sabalan volcano
• west alborz