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Abstract

On the basis of field observations, petrographic evidences and chemical data two types of sodic-calcic and potassic alterations have been identified in the center and margin of the Panj-kuh intrusive body, respectively. Development of albitization on the corner of plagioclase crystals, presence of albite with chess board twining, scapolitization of plagio-clase, high sphene and apatite content comparing with fresh igneous protolith and a general absence of magnetite are the most important evidences of sodic-calcic alterations in monzonitic rocks. Potassic alteration is defined by the presence of the shreddy aggregates of hydrothermal biotite and replacement of plagioclase by K-feldspar. Some elements such as Na2O, CaO, MgO, TiO2, P2O5, Sr, V and Sc are increased in sodic - calcic alteration at the same time as K2O, FeO?, Ba, Zr and Rb show decrease, whereas, potassic alteration show reverse trends. These evidences indicate that some elements such as Fe, K, and so on, leached from sodic-calcic zone and transported to the potassic zone by hydrothermal fluids.

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