Geochemistry and Petrogenesis of Gandom-Berian Quaternary Alkali Basalts, North of Shahdad, Kerman Province

Gandom-Berian area, located on southern part of the Kavir-e Lut, covers an area around 480 km2 and morphologically is a covered messa by very dark basaltic lava flows. Their major minerals are olivine and clinopyroxene phenocrysts along with plagioclase microlites and their main textures are microlitic porphyry to glomeroporphiry with interestal to intergranular groundmass. The in line position of volcanic cones along the line of movements of Nayband fault show its effect on the formation of Gandom-Berian basaltic magma. The genetic realationship of these lava flows with deep seated lithospheric fractures as a result of Nayband fault, the presence of mantle xenoliths and alkaline nature of basalt all reveal a fast deep ascending of magmas. Based on geochemical analysis and occurrence of nepheline in the norm composition the Gandom-Berian basaltic lava flows belong to basanite-tephrite group. The investigation on Gandom-beriyan alkali basalts clearly shows their relationships to an intera-continental extensional environment. Low ratio of Ce/Nb, Th /Nb, U/Nb, Ba/Nb and High levels Zr with mean 234.81 indicate a none depleted asthenospheric mantle source the origin of Gandom-Berian basaltic lava flows. Enrichment and depletion of light and heavy rare earth elements respectively indicate the existence of garnet in the source rock.