Trachyandesites, trachytes and latites associated with ignimbrite and pyrocalstic rocks, characterized by shoshonitic affinity are the main Plio-Quaternary volcanic rocks in the Sabalan region (Ardabil). Plagioclase, K-feldspar, biotite associated with clinopyroxene and glass are the main constituents of these lavas. Plagioclases are andesine to labradorite while clinopyroxenes have augitic composition. The Sabalan volcanic rocks show enrichment in LREE relative to HREE and are characterized by enrichment in LILE and depletion in HFSE. Petrological observations along with geochemistry of rare earth and trace elements of these lavas suggest shoshonitic affinity and derivation from a subduction zone. The Sabalan volcanic rocks are isotopically characterized by derivation from an enriched mantle source (with/without crustal influence) with tendency to plot in a field defined by island-arc basalts (IAB) and OIBs (in 4Nd vs. 87Sr/86Sr diagram). The geochemical and isotopic signatures of the Sabalan lavas suggest that their magma has been issued via low degree partial melting of a subduction-metasomatized continental lithospheric mantle. The formation of these lavas is linked to slab steepening and break-off in a post-collisional regime.
کلید واژگان :Geochemistry; Sr-Nd isotopes; Petrogenesis; Plio-Quaternary lavas; Sabalan.
ارزش ریالی : 600000 ریال
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