Magnetotelluric (MT) Data Analysis and 2D Modeling of the Kutai Basin, Indonesia: Preliminary Results

Magnetotellurics (MT) is a passive electromagnetic method that measures fluctuations of electric and magnetic fields at the earth’s surface. In this study, MT method is applied for basin delineation based on the resistivity contrast between sediments and basement. Thirty MT stations were deployed at eastern part of the Kutai basin, East Kalimantan, Indonesia. We analyzed the MT data using phase tensor analysis, to obtain the dimensionality and the geoelectrical strike of the subsurface. Most of the MT data are characterized by phase ellipse and low skew value (-3o < β < 3o). This indicates that MT data have 2D character with the direction of geoelectrical strike N 30o E. This result is in a good agreement with the geological strike that of NE-SW direction. We performed 2D modeling at two lines to obtain the resistivity configuration of the Kutai basin. The low resistivity anomalies may be associated with shale or black shale of the Pamaluan Formation showing geometries influenced by Samarinda anticlinorium and its fault structures.