Adrian, J.FZJ* ; Tezkan, B.

2017

Abstract: We present inversion studies obtained with a newly developed 2D inversion algorithm for DirectCurrent Resistivity (DCR) and Time-domain induced polarization (TDIP) data. The algorithm usesthe finite element approach on unstructured meshs which simplifies the incorporation oftopography. The model parameters resistivity and chargeability are connected by a perturbationapproach and the inversion is conducted in two steps.By inversion studies with synthetic data, it is shown that chargeability structures can be reproducedby the algorithm in presence or absence of a corresponding resistivity anomaly. A further studycompares the effects of different smoothness constraint matrices that approximate first orderderivatives of parameter transitions of neighboring mesh elements. It is shown that it is preferable touse a constraint that considers the shape and size of the elements of unstructured meshs overconstraints that weight all element boundaries equally. Furthermore, a method is presented thatapproximates a depth of investigation by deriving a threshold of sensitivity coverage from the ruleof thumb.As a case study, inversion results of field data acquired on a copper ore deposit located in Turkeyare presented. The ore deposit is elongated beneath a valley structure and has sulfide content. Dueto its disseminated form, resistivity anomalies induced by this deposit are hard to detect. However,chargeability inversion results show anomalies below 10 m depth with values of >100 mV/V. Thisclearly indicates the presence of ore with sulfide content.