Regional Paleomagnetism: Remanent Magnetism in Local Rocks of Nongalbibra, East Garo Hills, Meghalaya

This study analyzes the paleomagnetic properties of Nongalbibra rock samples, East Garo Hills, Meghalaya, for the purpose of creating a preliminary paleomagnetic record for use at high school level. Field work included systematic sampling of outcrops with accurate recording of GPS coordinates, strike, and dip, whereas laboratory testing utilized a handheld magnetic susceptibility meter and a simple fluxgate magnetometer. Five standard samples were investigated; intrusive basalt and metamorphic gneiss had high magnetic susceptibility (3.2–4.0×10⁻³ SI units) and intense natural remanent magnetization (1.5–2.0 mA/m) with almost identical vector orientations to that of expected geomagnetic field. Sample sandstone had much lower values (0.9×10⁻³ SI units; 0.5 mA/m). This fits with the argument that lithology has a controlling strong influence upon magnetic properties and implies differences in magnetic mineral composition.