Study of biotite quartzdiorite rocks of NW Delijan by using biotite mineral chemistry

The composition of skarn's mineralizing fluids is closely related to the physicochemical conditions prevailing during the cooling and crystallization of magma. Biotite is an effective indicator for determining the physio-chemical conditions prevailing during the cooling and crystallization of magma. In this study, the biotite composition of Sarvian biotite quartz diorite from Urmia-Dokhtar magmatic arc was investigated to estimate the magma crystallization conditions and also to determine the petrological and metallogenic characteristics of the granitoid rocks.

The study area is located 15 km northeast of Delijan city and in Markazi province (Figure 1). Miocene Sarvian quartzdiorite rocks are classified into three subgroups: quartzdiorite, micro quartzdiorite and biotite quartzdiorite. In this study, 21 spots of Sarvian biotite quartzdiorite were analyzed at the Iran Mineral Processing Research Center (Table 1).

The biotites of Sarvian granitoid are crystallized at a temperature of about 750 ° C, oxygen fugacity is between 10-11 and 10-13 and the pressure is about 0.6-1.1 kbar. The mentioned crystallization conditions indicate that the biotite quartzdiorite rocks of Sarvian crystallized at high temperature, shallowly and under high oxygen fugacity conditions. In addition, it shows that Sarvian biotite quartzdiorite has a high chance of mineral exploration. Placement of Sarvian biotite quartzdiorite rocks in Cretaceous limestones and Eocene pyroclastics, crystallization at a pressure of about 1 kbar and the mentioned crystallization conditions, indicate the formation of skarns in the region. The formation of skarn iron ores in the area is a confirmatory examination that has been performed on the studies.

Emplacement of Sarvian biotite quartzdiorite rocks are at shallow depth and crystallization at high temperature conditions. High magnesium calc-alkaline magmatic series, high oxygen fugacity and type I orogenic granites from subduction of the oceanic crust below the continental plate leads to magma which is the result of melting and mixing of crust and mantle. So it has created suitable conditions for the formation of metal skarns.