Writers : Samadi,R.; Mirnejad, H.; Shirdashtzadeh, N.; Kawabata,H.
Refference : The first international applied geological congress; Department of geology Islamic azad university- Mashhad
Publishing Year : 2010

Abstract :

Tonalites are mineralogically comprised of quartz, plagioclase (mainly bytownite), garnet (almandine-pyrope), biotite (annite), amphibole (ferro-hornblende), and accessory minerals of chlorite, epidote, calcite, and ilmenite. Based on the geothermobarometrical investigations, the tonalitic melt have had an average temperature and pressure of up to 680oC and 6.4 kbar and the contact metamorphic rocks produced by its intrusion show lower metamorphic degrees (Albite-epidote to hornblende hornfels facies) in compare to schists of area (green schist to amphibolite facies). Thus the by effect of this intrusion, compared to the regional metamorphism of area, is just seen around the intrusive mass of tonalite. Petrography and geochemistry of tonalites and their garnets composition revealed that the parental magma of Dehnow tonalitic rocks was an I-type granitoiid, belonged to calcalkaline series and related to CAG tectonic setting.

Subject List : Tonalit