The fibrolite enigma: A study of occurrence and variety of fibrolites in the metamorphic and plutonic rocks of the Hamadan region
|Location||The 25 Symposium of Geosciences|
|Author||A. A. Sepahi -S. R. Jafari -S. Mani-Kashani|
|Holding Date||01 July 2007|
In the Hamadan region, fibrolite occurs in many regional and contact metamorphic rocks (i.e. schists, migmatites and hornfelses), and also in some plutonic and vein rocks. It has commonly nucleated inside and around the other minerals such as garnet, cordierite, kyanite, sillimanite, biotite, feldspar and also in the groundmass of the rocks. Peraluminous affinity of rocks and minerals which were related to the formation of fibrolites as well as rapid heat gradients and possibly existence of fluid phases in the vicinity of the intrusive bodies has been essential factors for the generation of fibrolites in these rocks. The fibrolite crystallites of the metamorphic and plutonic rocks of the Hamadan region have very variable diameters, so that, there are continuous changes (in a range or a spectrum) in the diameter of sillimanite needles from fibrous (fibrolite) to prismatic sillimanite. The inherent heat for the fibrolite nucleation and growth, has been possibly provided by intrusive bodies and related fluids.