Writers : VaUzadeh.M.V and Ghasemi.H
Refference : Geosciences Scientific Quarterly Journal,No.:7,P.:74

Abstract :

Bum- Miandasht region is situated southeast of Aligudarz and Juxtaposed to the Zagros Thrust.The activities of Zayandeh Rud, Najafabad reverse faults and the Main Zagros fault, induced the exposures of Precambrian,Upper Precambrian-Lower Cambrian, Triassic and Jurassic metamorphic complex. The effects of various metamorphic eposides at different times can be observed on these rocks.Following the Laramian orogeny,the intrusive granitoid massif, affected the metamorphic rocks of the region. Geochemical investigation indicates that the mentioned magmatic massif is of calc- alkaline type.
The same study shows that the intrusion of basic magma, derived from the mantle,led to melt partially a
large portion of lower crust. The differentiated basic magma, having tonalitic composition, subsequently mixed with anatectic acid granite and produced a hybrid magma, which on cooling gave rise to the granitoid massif of the region.The tectonic discrimination diagrams showed that the granitoid massif is of post-orogenic type.Additionally, regarding the geochemical affinities with other granitoids of adjacent regions (Borujerd, Hamadan,Shazand,Aligudarz and others), they have been injected after the Laramian orogeny.

Subject List : granit