Magnetic gradiometer survey in granitic and sedimentary geology

Earth's magnetic fields are recorded in the rocks. Iron-bearing minerals contain in many rocks act as tiny magnets. From igneous rocks to sedimentary rocks, all rocks have a magnetic record. Magnetic gradiometer survey was used to study the difference between magnetic field value of granite geology and sedimentary geology. Magnetic gradiometer survey can measure the local disturbances in the earth's magnetic field caused by the presence of magnetic materials. Thus, the quantification of variations and concentration of magnetic grains in rocks can be defined. Magnetic gradiometer survey is one of the components in geophysical magnetic method which utilized two sensors differs from magnetic survey with one sensor only. The study sites were in two different places with different geological area. The site with granitic geology was inside the campus of Universiti Sains Malaysia, Pulau Pinang while the site with sedimentary geology was in Gelang Patah, Johor. Both sites have almost the same pattern of survey lines with maximum of 10 meter station spacing which been conducted through 0.9 meter magnetic sensor spacing. Based on anomalies signature on the contour maps the qualitative interpretation is made while the quantitative interpretation is made based on data modeling. From the magnetic gradient contour map calculated and extrapolated from raw data, there is significance difference in value of magnetic field between granitic geology and sedimentary geology.