Shahsavaran (volcanic field) west

 volcano, volcanic plateau

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Volcanic FieldShahsavaran is a volcanic field in Iran. It covers an ellipse shaped area west of Bazman volcano. The field has erupted lava cones and lava flows, along with some explosive volcanic activity especially in the eastern part of the field. Volcanic rocks in the field are dominated by andesite, with subordinate basalt, dacite and rhyodacite. The volcanism has lasted from 12 million years ago to recent times, the 2010 Hosseinabad earthquake took place within the field but seems to be unrelated to volcanic activity.
The field has a surface area of 60 by 120 kilometres (37 mi × 75 mi),[1] with the shape of an ellipse.[2] This ellipse "points" to the volcanic arc formed by the Bazman, Taftan and Koh-i-Sultan volcanic arc.[3]

The field features well preserved lava cones, associated with lava flows.[1] The basal basaltic lava flows are interlayered with volcanic debris and more silicic lava flows.[4] To a more recent phase of volcanism belong andesitic centres, some of which lie on river terraces and form easily recognizable coulees.[4] Explosive activity has also left ignimbrites and pumices;[2] such explosive activity took place in the eastern part of the field towards Bazman volcano and was accompanied by the formation of nuee ardente breccia.[4]

Petrology and petrogenesis[edit]
The field has erupted basalt,[1] which forms several 1 kilometre (0.62 mi) long lava flows in the basal units of the field. Andesites form the bulk of the products with subordinate dacites,[2] as well as some rhyodacites which are found in the eastern part of the field, where the explosive activity took place.[5][4] The dacites are found in the eastern part of the field. The rocks are porphyritic and follow the calc-alkaline trend,[2] except the basalts which are of the Al-rich variety. Elemental composition is typical for island arc volcanoes, although Sr content is rather high.[6] The rocks contain phenocrysts of clinopyroxene, orthopyroxene and plagioclase.[2] Amphibole and olivine is also found in the rocks. Some rocks have a glassy composition.[6] These rocks probably formed by subduction of oceanic crust and the interaction of anatexis products thereof with abovelying mantle, with some fractionation of the subsequently formed magma.[7] The basement of the area is formed by even older (Oligocene-Eocene) volcanic rocks that contains intrusions of granodiorite.[2]