The geological origin of the Umm Al-Binni Lake within the Ahwar of Southern Mesopotamia, Iraq
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ORIGINAL PAPER
The geological origin of the Umm Al-Binni Lake within the Ahwar of Southern Mesopotamia, Iraq Varoujan K. Sissakian 1,2 & Hayder A. Al-Bahadily 3 Received: 18 May 2018 / Accepted: 15 October 2018 / Published online: 6 November 2018 # Saudi Society for Geosciences 2018
Abstract The Umm Al-Binni Lake is one of the well-known lakes within the Ahwar of southern Mesopotamia in Iraq. It is located about 45 km north of the confluence of the Tigris and Euphrates rivers. The Umm Al-Binni Lake has been postulated as a-meteoriteimpact crater, particularly by geo-archeologists, based on indices such as shape, size, depth, and the presence of a perceived lakerim structure. However, no unambiguous evidence of such an impact has been put forward to date though. The lake measures 3.4 km in diameter, and it has a polygonal shape, with a maximum depth of 3 m. The age of the alleged crater was estimated to be less than 5000 years (or earlier than 3000 BC), based on the reported deposition rates of the Tigris–Euphrates delta sediments as a result of the Holocene sea-level changes of the Arabian Gulf during that time around the Umm Al-Binni Lake area. In the current study, using geophysical data and remote-sensing techniques investigates the origin of the Umm Al-Binni Lake. The results of magnetic and gravity analyses showed that the Ahwar area of southern Mesopotamia, including the Umm Al-Binni Lake, was subjected to the differential subsidence of the basement faulted blocks, as the distribution of the lakes is mostly controlled by such basement tectonic zones of weakness. Satellite imagery also showed some evidence of anthropogenic activity that contributed to the shaping of the southern sector of the Lake rim, which locally displays an angular shape. None of the latter evidence could support any meteorite-impact origin for the Umm Al-Binni Lake. Keywords The Umm Al-Binni Lake . Ahwar . Meteorite-impact crater . Satellite images . Gravity and magnetic data analysis . Southern Mesopotamia . Neotectonics . Basement lineaments . Iraq
Introduction Southern Mesopotamia (i.e., the southeastern part of Iraq) is characterized by vast marshlands of shallow-water lakes and vegetated mashes mostly by reeds (locally called Ahwar) (Aqrawi 1993; Aqrawi and Evans 1994). They can be divided based on their location to the following: Eastern, Central, and Southern Ahwar (Fig. 1). They are all developed along the lower reaches of the Tigris and
* Varoujan K. Sissakian [email protected]; [email protected] Hayder A. Al-Bahadily [email protected] 1
University of Kurdistan, Hewler, KRG, Iraq
2
Private Consultants Geologist, Erbil, Iraq
3
Senior Chief Geophysicist Iraq Geological Survey, Baghdad, Iraq
Euphrates rivers and their prograded ancient delta (Aqrawi 1993) within the Mesopotamian Plain (Yacoub 2011a; Sissakian and Fouad 2012). Among those Ahwar, tens of open lakes of different sizes and shapes are developed and scattered across southern Mesopotamia. Such lakes are free of reeds and other vegetation types due t
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