Found 7 datasets

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A resistivity-depth model of the central Azraq basin area, Jordan: 2D forward and inverse modeling of time domain electromagnetic data

The focus of this thesis is the geophysical exploration of the central part of the Azraq basin in the northeastern desert of Jordan. In addition to common 1D inversion techniques, further 2D forward modeling strategies and a rarely used 2D inverse modeling scheme are applied to transient electromagnetic data. The Azraq area is of potential interest for palaeoclimatical and archaeological research in the frame of the interdisciplinary Collaborative Research Centre 806, entitled "Our Way to Europe" (CRC 806)....
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Investigation of the Azraq Basin in the Eastern Desert of Jordan using Integrated Geoelectrical Techniques

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Investigation of the Azraq sedimentary basin, Jordan using integrated geoelectrical and electromagnetic techniques doi

The Eastern Mediterranean has been used as a passageway for human migration from Africa to the Middle East, the Balkans and Europe. The Azraq basin in the eastern desert of Jordan has been a major spot for human settlements since the middle Pleistocene. The former lake in the basin centre has developed to a hyper-saline alluvial mudflat, the Qa’ Al Azraq. In the mudflat thick sequences of alluvial sediments are deposited. Such sediment successions are promising archives used for reconstructing a...
Keywords: GQT2
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Aquatic community response in a groundwater-fed desert lake to Holocene desiccation of the Sahara doi Spatial

The finely laminated sediment record of a permanent, hypersaline, desert oasis lake in the Ounianga region of northeastern Chad presents a unique opportunity to document the hydrological evolution of this groundwater-fed aquatic ecosystem during mid- and late-Holocene desiccation of the Sahara. In this study we reconstruct long-term changes in zoobenthos and zooplankton communities of Lake Yoa as their early-Holocene freshwater habitat changed into the hypersaline conditions prevailing today. Chironomid...
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Varved sediments of Lake Yoa (Ounianga Kebir, Chad) reveal progressive drying of the Sahara during the last 6100 years doi Spatial

The sedimentological and geochemical properties of a 7.47 m long laminated sequence from hypersaline Lake Yoa in northern Chad have been investigated, representing a unique, continuous 6100 year long continental record of climate and environmental change in the eastern Central Sahara. These data were used to reconstruct the Mid to Late Holocene history of this currently hyper-arid region, in order to address the question of whether the Mid Holocene environmental transition from a humid to a dry Sahara was...
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Modern and early Holocene mollusc fauna of the Ounianga lakes (northern Chad): implications for the palaeohydrology of the central Sahara doi Spatial

The fresh and saline lakes of Ounianga Kebir and Serir in northeastern Chad are among the very few permanent aquatic ecosystems currently existing in the hyper-arid core of the Sahara desert. The confirmed modern fauna of aquatic molluscs at Ounianga comprises three widespread species (Melanoides tuberculata, Biomphalaria pfeifferi and Lymnaea natalensis), of which only the first appears to maintain a thriving population. We recovered seven more species of gastropods, among which one is new to science...
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Climate-Driven Ecosystem Succession in the Sahara: The Past 6000 Years doi Spatial

Desiccation of the Sahara since the middle Holocene has eradicated all but a few natural archives recording its transition from a “green Sahara” to the present hyperarid desert. Our continuous 6000-year paleoenvironmental reconstruction from northern Chad shows progressive drying of the regional terrestrial ecosystem in response to weakening insolation forcing of the African monsoon and abrupt hydrological change in the local aquatic ecosystem controlled by site-specific thresholds. Strong reductions...
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