P Ahmadi Moghadam; H Ahmadipour
Abstract
A part of the Hezar volcanic complex (Urmia-Dokhtar Volcanic Belt), Eocene in age, has been cropped out in the CheheltanMountain at southwest of the Bardsir town, in the Kerman province. This part consists of alternation of lava flows, pyroclastics and epiclastics that are cut by several gabbroic and ...
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A part of the Hezar volcanic complex (Urmia-Dokhtar Volcanic Belt), Eocene in age, has been cropped out in the CheheltanMountain at southwest of the Bardsir town, in the Kerman province. This part consists of alternation of lava flows, pyroclastics and epiclastics that are cut by several gabbroic and dioritic intrusions and dykes. The lava flows can be divided into andesites and basalts and the pyroclastics consist of volcanic breccias, agglomerates, ignimbrites and fine-grained tuffs. The epiclastics consist of several layers of volcanic sandstones and conglomerates that cover a vast area. Alternation of lava flows, pyroclastics and epiclastics show that the volcanic activities in the area have been done periodically from stratovolcanoes and when intensive volcanic eruptions were ceased epiclastics were deposited. It seems that lava flows and pyroclastics have been formed by volcanian and in some cases, plinian eruptions, and continuous basin subsidence during volcanic eruptions have led to the formation of thick layers of pyroclastics and epiclastics. The field evidences such as lacking of unconformities and paleosols show that there is no great interval between volcanic eruptions. The geochemical characteristics indicate that the lava flows probably have the same origin. It seems that fractional crystallization was the main process in the evolution of parental magmas, while crustal contamination played a minor role, so that the andesitic lava flows were produced by fractional crystallization of the basalts and the magmas had no very long stops en rout to the surface.
