The study of petrography, geochemistry and petrogenesis of the basaltic rocks, NE-Qorveh (Kurdistan)


1 Department of Geology, Faculty of Sciences, Bu-Ali Sina University, Hamedan, Iran

2 همدان- خیابان شهید فهمیده- دانشگاه بوعلی سینا- گروه زمین شناسی


In the northeastern part of Kurdistan province, there are many volcanic cones that are basaltic in composition. Petrographic investigations reveal these rocks are dominated by clinopyroxene and olivine phenocrysts and plagioclase and pyroxene micro crystals, while space between them is filled by opaque mineral and brown glass. The presence of zoned pyroxenes and sieve texture in these rocks are evidences of crustal contamination and magmatic unequilibrium. The studied rocks with 5-14% normative nepheline are alkaline nature. On Harker diagrams fractional crystallization is indicated by MgO decreasing while CaO, FeO, Ni, TiO2 and Cr and SiO2 increase. On discriminated diagrams the tectonic environment of the samples is inter continental extensional zone. Geochemical characteristics such as LILE, LREE enrichment, Nb, Ta and Y negative anomalies, positive anomalies of Ba, Pb, Th and Th/Yb enrichment suggest that the basaltic lavas studied derived from lithospheric mantle that contaminated by subduction fluids. Also, Zr/Hf and Hf/La ratios are evidence for upper crustal contamination. High (Th/Yb)N, (La/Yb)N and high Nb anomaly (0.37-0.98) show that the magma generated from a garnet lherzolitic source.