Evaluation of Semanggol Formation (Permian Facies) Using Electrical Resistivity Tomography and Seismic Refraction Tomography Parameter

Outcrop studies are a fascinating part of geology as it evidently shows the aftermath of how the earth forming processes billion years ago. Outcrops do not cover majority of the Earth's land surface as it is covered by soils or vegetation thus cannot be seen clearly. In Kedah, Malaysia, there are many outcrops exposed in the state. The aim of this research studies was to correlate the parameters of geophysical survey with the properties of the Permian facies of Semanggol Formation in Kedah. The Permian facies consists of bedded chert and claystone. Two geophysical technique, electrical resistivity tomography (ERT) and seismic refraction tomography (SRT) were applied at the same line on top of the outcrop at Bukit Kukus beside Kulim - Baling (Kedah) road. The arrays used for ERT are Pole-dipole and Wenner-Schlumberger. The spacing between electrodes for ERT is 1.5 m while the geophone spacing for SRT is 2 m. Both ERT and SRT line is 60 m and 46 m respectively. Based on the results of both geophysical techniques, relating the porosity and permeability (poroperm) with geophysical parameters, it can be concluded that the bedded chert of low poroperm having seismic velocity and resistivity values at range of 1500 m/s - 2500 m/s and 1400 Omega m - 45000 Omega m. Whereas for claystone, it is very soft and laminated, concluding having high poroperm with seismic velocity between 600 m/s - 1200 m/s and resistivity values between 400 Omega m - 1000 Omega m.