A Newly Developed 2D DC and Time-domain IP Inversion Algorithm -Application on Data Acquired on an Ore Deposit in Turkey

We present the application of a newly developed 2D direct current (DC) resistivity and time-domain induced polarization (TDIP) inversion algorithm on synthetic and on field data. The algorithm applies local smoothness constraints and error weighting. The inversion is conducted in two steps. First, an effective resistivity model is obtained from inversion of the measured apparent resistivity data. Subsequently, a non-linear IP inversion is applied resulting in a chargeability model of the subsurface. The implemented forward calculation uses the Finite Element (FE) method. Unstructured triangular meshes are used for all forward and inverse calculations allowing the incorporation of complex surface topography in the inversion mesh.

A modeling study with synthetic data shows that the algorithm is capable of resolving chargeability anomalies independent from the corresponding resistivity anomaly. This is important for disseminated deposits, since the resistivity signature of finely distributed material might be insignificant whereas the IP effect of ores, especially sulfides, is strong.

The inversion of DC/TDIP field data acquired on a (mainly disseminated) copper ore deposit in Turkey reveals a strong IP effect, as expected, which is interpreted to be caused by sulfidic copper ore content.