The investigation of skarn mineralization at Alam-Kuh in Kelardasht area (North of Iran) with special view on fluid inclusions studies

The widespread stratigraphic sequences, from Precambrian to Cenozoic have been affected by metasomatic and thermal- metamorphic events of the Pliocene age by the Alam- Kuh alkali-granitic intrusion. Skarnification is the main metasomatic type in the studied area with 1-2km in extent. This intruded alkali-granite is probably related to syn-collision and post collision tectonic regimes as A-type granite. Intrusion of alkali-granitic rocks into the surrounded wall rocks caused to form the skarn zones and oxide-sulfide mineralization, mainly consists of magnetite and some chalcopyrite as well as pyrite. The fluid inclusion studies show five types of inclusions in quartz synchronous with mineralization as V + L + S, V + L, L + V, L, and V. Geothermometric evidences indicate temperatures of 478°C- 488°C and 368°C- 378°C for oxide phase formation and sulfide mineralization respectively. Magmatic and meteoric fluids mixing are effective in generation of fluids during mineralization processes. The field geology evidences, microscopic and geothermometery characteristics suggest a skarn origin for the metallic mineralization of the Alam- Kuh intrusive body.