Review and comparing geochemistry of barren and productive hypabbysal intrusive bodies considering evidence for adakitic rocks in the Dehaj-Meiduk area (North Shahrbabak)

Dehaj-Meiduk area is located at North of Shahre-babak. There are nine porphyry intrusive bodies in this region, which include Meiduk, Parkam, Iejoo, Segino, Chah Firouzeh, Narkoh, Ayoub Ansar, Sara and Keder. Meiduk, Chah Firouzeh, Parkam, Iejoo and Segino are productive among them and Narkoh, Keder, Ayoub Ansar and Sara are barren. These intrusive bodies are mostly composed of porphyry diorite, quartzdiorite and granodiorite. Geochemical studies indicate that the magma of these rocks has the peraluminous to metaluminous nature and magma series are calc-alkaline with high potassium and shoshsonitic nature. The geochemical variation diagrams of major oxides and minor elements, illustrate the continuous spectrum of rock compositions for the studied samples, which indicates high crystallization differentiation during magmatic processes. Field observations, petrographic and geochemical studies suggest that the rocks in the Dehaj-Meiduk area are I type. All available data demonstrate that these rocks are result of subduction of Neotethyan oceanic crust beneath the central Iran continental crust. Flat subduction happened in some parts of the study area and because of that, partial melting rate has been low and as a result adakitic rocks are produced. The adakitic rocks have formed intrusive bodies in Pliocene. Since magma is depleted in metallic elements by forming earlier stage productive plutons, the later rocks do not contain metallic elements and are barren.