Variation in Anisotropy of Magnetic Susceptibility with Depth in the Upper 1 km of the Earth’s Crust in Singhbhum Region (India) – First Results

Abstract

In this paper the first results of anisotropy of magnetic susceptibility (AMS) studies carried out on 10 schist samples taken from different depths of a borehole in the vicinity of Singhbhum Shear Zone (SSZ) are presented. A cube of 8 cm3 volume was extracted from each borehole sample and its AMS was measured; the shallowest sample is from 112 m depth, while the deepest is from 850 m depth. In the depth vs. mean magnetic susceptibility (Km) plot, a sharp decrease in the Km values is noted in samples from 547 m and 588 m depths. Microstructural investigation of the different samples reveals presence of thick quartz veins in samples from the above mentioned depths vis-à-vis other samples. Petrographic studies also reveal presence of the mineral “allanite” in sample from 547 m depth, which contained a thick quartz vein. It is thus suggested that studies involving AMS investigation of borehole samples from the top 1 km depth of the region hold promise in mineral exploration studies.