Geochemical and Petrogenesis of Granitoides rocks in South-East of Centeral Iranian Volcanic Belt, North-West of Share-Babak, Kerman Province, Iran

Abstract

In the Centeral Iranian Volcanic Belt (CIVB), north-west of Shahre-Babak, in area of Javazm, Dehaj and khabr, about 20 plutonic porphyritic tonalitic to granodioritic masses (1-50 km2) are intruded into a varity of rock sequences from Eocene to Early Miocene in age. Tonalitic and granodioritic rocks are some part of Dehaj-Sardoieh belt and having early Miocene age. The CIVB contains intrusive and extrusive rockes of Cretaceous-Quaternary age. Geochemical studied indicate that the subalkalic tonalitic to granodioritic masses belong to I-type granitoides and have an adakitic composition tendency with Na2O/K2O (1.82-2.57), high Sr (584-1040 ppm), Mg#=(0.2-0.52) and low Y (7.3-10.7ppm), low Yb (0.7-1.18ppm), and low HREE. Fractionated REE patterns show that, (Ce/Yb)N = 10-22, absence of negative Eu anomaly, low content of Y, Nb, Ti, and high Sr/Y (74-134) and (Ce/Yb)N ratios. Based on geochemical data the source of tonalitic and granodioritic magma was probably garnet-amphibolite or amphibole-eclogite, possibly generated during subduction of the Neo-Tethyan oceanic slab beneath the Central Iran microplate. The adakitic plutonism was followed by adakitic volcanism in Mio-Peliocene and eruption of alkaline magmatism in this area. The thermal needs for slab melting results the shear stress of oblique convergent. The tectonic setting of tonalitic and granodioritic masses are an active continental margin and belong to volcanic arc granitoides.

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