Scientific Quarterly Journal of Geosciences

Scientific Quarterly Journal of Geosciences

Interpretation of magnetic fabrics based on variations of anisotropy of magnetic susceptibility (AMS) in Bouin- Miandasht granitoid pluton

Document Type : Original Research Paper

Authors
S Saki 1
H Ghasemi 2
M Sadeghian 2
1 M. Sc., Faculty of Earth Sciences, Shahrood University of Technology, Shahrood, Iran
2 Associate Professor, Faculty of Earth Sciences, Shahrood University of Technology, Shahrood, Iran
10.22071/gsj.2016.41261
Abstract
Bouin- Miandashtgranitoid pluton with an area of 40 Km2, outcropped in the north of Bouin Miandasht- Aligoudarz road, was emplaced into Triassic to early Jurassic low to medium grade metapelitic rocks of Sanandaj - Sirjan structural zone. This pluton composed of alkali feldspar granite to leucogranite. For the first time, variation of anisotropy of magnetic susceptibility (AMS) is applied to investigate magnetic fabric of this pluton. The Mean magnetic susceptibility values (Km in µSI) of the different rock groups of Bouin- Miandasht pluton are as follows: alkali feldspar granites (158), fine granites (120), coarse granites (166), and leucogranites (34). The lower Km values for the main compositions of this pluton (< 500 µSI) suggesting the paramagnetic nature of these granites. Biotite is the main carrier of magnetic properties in the studied rocks. The magnetic anisotropy (P %) varies from 1 to 15. Aalkali feldspar granites have the highest P value and show positive correlation with degree of deformation. Shape parameter of magnetic ellipsoid (T) values varies from -0.43 to 0.85 and most of the magnetic ellipsoids are oblate. Seventy five percent of specimens have positive T value. This subject indicates that magnetic ellipsoids are oblate and then foliation is prevailing, and also field evidence confirms this conclusion.
Keywords
Anisotropy of Magnetic Susceptibility
Magnetic fabrics
Paramagnetic
Bouin - Miandasht
Sanandaj-Sirjan
Scientific Quarterly Journal of Geosciences
Volume 25, Issue 98 - Serial Number 98
No. 98, Winter 2016
Winter 2016
Pages 385-394