TY  - JOUR
A1  - Mörbe, Wiebke
A1  - Yogeshwar, Pritam
A1  - Tezkan, Bülent
A1  - Hanstein, Tilman
T1  - Deep exploration using long-offset transient electromagnetics: interpretation of field data in time and frequency domain
Y1  - 2020
VL  - 68
IS  - 6
SP  - 1980
EP  - 1998
JF  - Geophysical Prospecting
DO  - 10.1111/1365-2478.12957
DO  - 10.23689/fidgeo-4467
N2  - In the framework of the Deep Electromagnetic Soundings for Mineral Exploration project, we conducted ground-based long-offset transient-electromagnetic measurements in a former mining area in eastern Thuringia, Germany. The large-scale survey resulted in an extensive dataset acquired with multiple high-power transmitters and a high number of electric and magnetic field receivers. The recorded data exhibit a high data quality over several decades of time and orders of magnitude. Although the obtained subsurface models indicate a strong multi-dimensional subsurface with variations in resistivity over three orders of magnitude, the electrical field step-on transients are well fitted using a conventional one-dimensional inversion. Due to superimposed induced polarization effects, the transient step-off data are not interpretable with conventional electromagnetic inversion. For further interpretation in one and two dimensions, a new approach to evaluate the long-offset transient-electromagnetic data in frequency domain is realized. We present a detailed workflow for data processing in both domains and give an overview of technical obstructions that can occur in one domain or the other. The derived one-dimensional inversion models of frequency-domain data show strong multi-dimensional effects and are well comparable with the conventional time domain inversion results. To adequately interpret the data, a 2.5D frequency-domain inversion using the open source algorithm MARE2DEM (Modeling with Adaptively Refined Elements for 2-D EM) is carried out. The inversion leads to a consistent subsurface model with shallow and deep conductive structures, which are confirmed by geology and additional geophysical surveys.
UR  - http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/8813
ER  -