ژيوشيمي و محيط تكتونيكي سنگ هاي آتش فشاني پاليوزوييك زيرين در دره جهق (جنوب كاشان)

Gochemistry and Tectonic Setting of Early Paleozoic Volcanic Rocks in Jahagh Valley (South of Kashan)

Jahagh anticline in south of Kashan is host to the Silurian volcanic rocks at the base of Niure formation (with sandstone lithology).This area is located in the western edge of Central Iran zone. The volcanic rocks under study involved basalt until trachy basalt and contain Plagioclase. These rocks belong to alkali basalt to sub- alkali basalt field on the geochemical diagrams.The investigation of rare earth elements indicate garnet presence in the source with low partial melting degree. High Ti and Zr content in these rocks show that the magmatic series is alkaline- transitional. The geotectonic setting is intracontinental rift that follow the extension phases after Caledonian orogeny and creatie the deep faults in Iran cratonic crust. In all probability, Isfahan fault activation that is one of the old and basal faults in this area cause the eruption and volcanism at Silurian in this part of Iran.