petrlojicprocess modelling and empaced anderian Granitoid Intrusion in westherr north ofI RAN

Category Petrology
Group GSI.IR
Location 20th symposium on geosciences
Holding Date 16 April 2008

     Anderian Granitoid Intrusion (AGI) contains a complex of granitoid plutonic bodies with Eocene-Oligocene age, which are I- type in character and are emplaced in continental volcanic arc setting. The AGI appears as stock, dyke and sill and can he classified into four distinct series based on chronological order. Evidence from field and petrographical studies and trace elementmodeling show that fractional crystallization of plagioclase and hornblende was the most effective process in AGI magmatic evolution. Crystallization rates of plagioclase and hornblende, based on Ba-Sr vector diagram modeling, are determined
approximately 30 and 20 percent, respectively. The same process tends to produce a gradual and relative zoning in magma chamber, therefore the basic compositions lies in the lower parts of the chamber, due to their higher densities. As a result, a gradual variety of rock compositions can be seen in the complex, with the early series of the complex having an acidic and the late ones having a relatively basic composition.

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