The investigation of anisotropy of magnetic susceptibility (AMS) and the emplacement mechanism of Darreh Bagh granitoid pluton (NW Aligudarz).

The Darreh Bagh granitoid pluton (DGP), with middle Jurassic age (178 Ma), located in the northwest of Aligudarz city. The pluton is mainly granodioritic composition which emplaced in metapelitic rocks of Sanandaj-Sirjan structural zone. For the first time, the emplacement mechanism of this pluton, investigated by anisotropy of magnetic susceptibility (AMS) method. Based on the present investigations, the mean magnetic susceptibility, in terms of µSI for the studied rock groups are as follow: granodiorites (257), leucogranites (47), high tourmaline leucogranites (148), low tourmaline leucogranites (48), migmatites (437), surmicaceous enclaves (386). Considering the obtained values, the felsic part of the DGP belongs to the paramagnetic granitoids (500>km>0 in µSI) (equal to ilmenite series or S-type). Based on the magnetic parameters and their interpretations it is possible to divide DGP into the A and B domains and A1, A2 subdomains. The magnetic lineations in the subdomains oriented to the north. Whereas in the middle part of the pluton (B domain) it oriented dominantly to the east and southeast. Based on distribution patterns of magnetic lineations these domains were emplaced with a short delay compared to each other. Meanwhile, A domain was emplaced prior to B domain. With attention to distribution patterns of magnetic lineations and foliations, the principles of interpretation of magnetic parameters and regional geological characteristics, the Darreh Bagh granitoid pluton was emplaced in the form of a relatively large sill in a dextral shear zone (related to a transpression regime). [ABSTRACT FROM AUTHOR]