فهرست مطالب mohsen tabatabaei manesh

The Oligo-Miocene Qazan granitoid body caused contact metamorphic of surrounding rocks and skarn formation in the wall limestone. The main intrusive rocks are essentially granite to diorite in composition. Two different types of skarn, exo and endoskarn have been developed. On the base of microprobe data, the northern skarn are characterized by zoning and the amounts of andradite and grossular changes oscillatory. While garnets from the southwestern skarn is predominantly andradite in composition. Using Fe/Ti vs. Al/ (Alᗯ) diagram that were calculated based on the mole percent of the used elements, it is estimated that about less than 50 percent hydrothermal waters were involved for the northern skarn whereas it was over this amount for the southwestern skarn. This leds to difference in garnet composition. The composition of clinopyroxene in both skarns is the same (diopside). As a result, hydrothermal fluids have not had much influence on pyroxene genesis. With regards to the occurrence of mineral assemblage and the presence of wollastonite in the skarns under study, these rocks have evolved in temperature above 500 ° C and O2 fugacity in the range of 10-17 to 10-15.

The skarns of the Ochestan area are located in the Sanandaj- Sirjan zone، about 60 Km south of Mahallat. The rock complex in this area consist of intrusive bodies and metamorphic rock such as: schist، phyllite، slate، hornfels، amphibolite and metavolcanic. The injection of magma in the Cretaceous-Paleocene with syenogranite and monzogranite composition into the Paleozoic limestone and dolomite led to formation of skarn and marble. Clinopyroxene (diopside)، olivine (forsterite)، tremolite، talc، serpentine، phlogopite، margarite، wollastonite، opaque minerals، calcite and quartz are observed minerals in contact metamorphism rocks. According to the mineralogical studies، the Ochestan skarns are exoskarn-type and the presence of minerals such as: forsterite، diopside، tremolite، antigorite and phlogopite show that the host rock is dolomitic the in study area. These skarns show zoning of intrusive body into the host rock: wollastonite skarn، pyroxene skarn، forsterite- serpentine marbles، mica marbles، tremolite- talc marbles، calcite and dolomite marbles.