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Yogeshwar, P. and Tezkan, B. (2017). Two-dimensional basement modeling of central loop transient electromagnetic data from the central Azraq basin area, Jordan. J. Appl. Geophys., 136. S. 198 - 211. AMSTERDAM: ELSEVIER. ISSN 1879-1859

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Abstract

Thick sedimentary sequences are deposited in the central area of the Azraq basin in Jordan consisting mostly of hyper-saline clay and various evaporates. These sediment successions form the 10 km x 10 km large Azraq mudflat and are promising archives for a palaeoclimatical reconstruction. Besides palaeoclimatical research, the Azraq area is of tremendous importance to Jordan due to groundwater and mineral resources. The heavy exploitation of groundwater has lead to a drastic decline of the water table and drying out of the former Azraq Oasis. Two 7 and 5 km long transects were investigated from the periphery of the mud flat across its center using a total of 150 central loop transient electromagnetic (TEM) soundings. The scope of the survey was to detect the thickness of sedimentary deposits along both transects and to provide a basis for future drilling activities. We derive a two-dimensional model which can explain the TEM data for all soundings along each profile simultaneously. Previously uncertain depths of geological boundaries were determined along both transects. Particularly the thickness of the deposited mudflat sediments was identified and ranges from 40 m towards the periphery down to approximately 130 m at the deepest location. Besides that, the depth and lateral extent of a buried basalt layer was identified. In the basin center the groundwater is hyper-saline. The lateral extent of the saline water body was determined precisely along both transects. In order to investigate the detectability of the basement below the high conductive mudflat sediments an elaborate two-dimensional modeling study was performed. Both, the resistivity and depth of the basement were varied systematically. The basement resistivity cannot be determined precisely in most zones and may range roughly between 1 and 100 Omega m without deteriorating the misfit. In contrast to that, the depth down to the basement is detected accurately in most zones and along both transects. Varying the depth of the basement or removing it completely results in a poor data fitting and, therefore, proves its significance. From the modeling study we derived bounds for the resistivity and depth of the base layer as a measure of their uncertainty. (C) 2016 Elsevier B.V. All rights reserved.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Yogeshwar, P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Tezkan, B. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-247633
DOI:	10.1016/j.jappgeo.2016.11.001
Journal or Publication Title:	J. Appl. Geophys.
Volume:	136
Page Range:	S. 198 - 211
Date:	2017
Publisher:	ELSEVIER
Place of Publication:	AMSTERDAM
ISSN:	1879-1859
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language TIME; DECOMPOSITION; FREQUENCY Multiple languages Geosciences, Multidisciplinary; Mining & Mineral Processing Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/24763