Petrogenesis of NW of Bam Volcanic Rocks Print

In the north and northwestern parts of Bam, extensive volcanism has occurred during Eocene time mainly composed of basic and felsic volcanic rocks associated volcanoclasitc, which are cut by different dykes. The volcanic rocks have sub alkaline and calc-alkaline to shoshonitic nature, while dykes are alkaline and potassic. In the spider diagrams, all samples show enrichment in the LILEs and depletion in the HFSs elements that coincide with the subduction related and upper crust rocks features. The studied rocks are enrichments in the LREE and show various (La/Yb)N. Andesy-basalts and andesites formed from evolution of primary magmas by MASH processes and primary magma originated from partial melting of a metasomatised spinal-lherzolitic source. Dacitic magma generated from partial melting of amphibolitic mafic lower crust while rhyolites were formed from partial melting of metagreywacke source in the crust. The dykes generated from less than 5% partial melting of metasomatized garnet- spinel-bearing lherzolitic mantle source. Eocene volcanism in Bam area ccurred during subduction of Neo-Tethys oceanic crust beneath the central Iran in a continental volcanic arc tectonic setting.