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Title of paper Geophysical Imaging of the Roter Kamm Crater in the Sperrgebiet National Park, Namibia, using TEM and AMT
List of authors Nienhaus, H., Yogeshwar, P., Mörbe, W., Tezkan, B., Lushetile, B., Melles, M.
Affiliation(s) Institute of Geophysics and Meteorology (University of Cologne), Institute of Geophysics and Meteorology (University of Cologne), Institute of Geophysics and Meteorology (University of Cologne), Institute of Geophysics and Meteorology (University of Cologne), Geological Survey of Namibia, Institute of Geology and Mineralogy (University of Cologne)
Summary The Roter Kamm Crater is a 3.7-million-year-old meteoritic impact crater in the Sperrgebiet National Park in southern Namibia. The geophysical exploration of the Roter Kamm Crater can lead to valuable information about its internal structure, as only a very limited number of geophysical studies had been carried out at this site. To be able to image the basement in the crater, two electromagnetic methods were selected: the Transient Electromagnetic (TEM) and the Audiomagnetotelluric (AMT) method. TEM is an active time domain method, that has already proven its capability imaging sedimentary deposits, is suited for investigations in shallow subsurface. AMT, on the contrary, is a passive frequency domain method that can reach penetration depths up to a few kilometres. Both methods are sensitive to good conductive structures. Within two weeks of fieldwork at the Roter Kamm Crater 153 TEM and 15 AMT soundings were carried out along three profiles. We measured TEM in a coincidence-loop setup for quadratic transmitter/receiver loops with an edge length of 50 m and 100 m. Additionally, TEM measurements were carried out in a fixed-loop-setup using 4 transmitter loops (edge length: 200 m). At each transmitter loop 11 soundings were conducted in profile and perpendicular to profile direction. The 1D inversion models of the TEM data showed a good conducing anomaly in a depth of 100 m, but only the AMT data could resolve the basement at a maximum depth of over 300 m in the centre of the Roter Kamm Crater. Overall, AMT and TEM are in very good agreement with each other and show the expected bowl-shaped anomaly in the impact.
Session Keyword 3.0 Exploration, Monitoring and Hazards
File upload 3.0_geophysical_imaging_of_th_nienhaus_03.pdf
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