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2D Inversion of Time Domain Induced Polarization Data Observed on the Black Shales Near Bramsche/Germany
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 25th European Meeting of Environmental and Engineering Geophysics, Sep 2019, Volume 2019, p.1 - 5
Abstract
Induced polarization measurements in the time domain (TDIP) are carried out near Bramsche/ Germany. The study area is well known for a lateral IP and resistivity anomaly caused by a thermally metamorphosed layer of Jurassic clays which marks the almost vertical Lias/Dogger boundary. Two kilometers westward of the survey area, the anomaly is geophysically well explored using radiomagnetotelluric (RMT) and DC-resistivity. The possible east continuation of the anomaly should be investigated with the new IP measurements.
The IP measurements were realized with the ABEM Terrameter LS device. In total, six parallel profiles with a length of 202.5 m and an electrode spacing of 2.5 m were investigated. A gradient array with a separate cable spread was chosen to eliminate electromagnetic disturbances by capacitive coupling between the potential and current multielectrode cables.
The data were inverted by using a newly developed 2D DC/IP inversion algorithm (Adrian and Tezkan, 2017) The algorithm uses finite elements and unstructured meshes. A clear lateral limited low resistive (5 Qm) and high chargeable (180 mV/V) anomaly was detected at about 15 m depth beneath all six profiles as a result of the 2D inversion indicating a good corrrelation with the geology.