Constrained interpretation of aeromagnetic data using tilt-angle derivatives from north-western part of Bangladesh

Md. Mahbubar Rahman¹ and Shaikh Enayet Ullah²

¹Department of Applied Physics, Electronics and Communication Engineering, Islamic University, Kushtia-7003, Bangladesh.

²Department of Applied Physics and Electronic Engineering, Rajshahi University, Rajshahi-6205, Bangladesh.

Corresponding author E-mail:mahbublv@yahoo.com

Accepted 12 August 2013

Abstract

This paper describes the implementation of tilt-angle derivative based algorithms on the interpretation of aeromagnetic data in the north-western part of Bangladesh. With consideration of subtle contributions from both shallow/deep seated magnetic anomaly sources, analysis of magnetic data using the tilt-angle derivative technique indicates the presence of three prospective magnetic anomaly sources with depth of occurrence less than 1.00 km in the north-western part and  Kishorgang upazilla of  Nilphamari district, Taragong and Badargong upazillas of Rangpur  district. The estimated values of magnetic susceptibility of the subsurface geologic features in such identified zones ranges from 20.00 ´10^-3 to 26.67 ´10^-3 SI units. The probable location of a deep-seated magnetic anomaly source at the north-western part of Chirrirbandar upazilla of Dinajpur district has also been detected and its estimated depth of 4.68 km is found to have in good agreement with the statistically estimated depth of  5.44 km. Results of the present study show that the subsurface geologic features occur at depths ranging from  0.22 to 4.68 km  with magnetic susceptibility  ranging from 0.12´10^-3 to 26.67´10^-3 SI. Based on the integrated borehole, geological, previous geophysical information and present findings, the present study has provided new insights on the occurrence of potential intrabasement magnetic intrusions in the north-western part of Bangladesh.

Keywords: Magnetic susceptibility, wavelength filtering, Tilt angle derivatives.