Uranium-series age determinations by mass spectrometric methods were done for travertines and ass... more Uranium-series age determinations by mass spectrometric methods were done for travertines and associated carbonate veins related to clastic deposits of the last glaciation (Pinedale) in the northern Yellowstone area. Dramatic variations in the hydrologic head are inferred ...
Chemical and stable isotopic compositions of groundwater samples from the Rub Al Khali (RAK) in s... more Chemical and stable isotopic compositions of groundwater samples from the Rub Al Khali (RAK) in southern Saudi Arabia were analyzed. Samples were collected from wells of variable depth (1.5–800 m) along the perimeter of the eastern half of the RAK including flowing ...
... open and productive wells tapping three types of aquifers: (1) fractured 187 basement (sample... more ... open and productive wells tapping three types of aquifers: (1) fractured 187 basement (samples: Bir Haroun, Bir Zeituna, Bir Halwagy, Bir Sahab, Bir Al ... groundwater samples from the ED (Sultan et al., 2007); and (3) data for 198 modern precipitation from Al Arish and Rafah (Fig. ...
ABSTRACT The Nubian Aquifer system of northeast Africa is one of the world's largest pota... more ABSTRACT The Nubian Aquifer system of northeast Africa is one of the world's largest potable groundwater reserves. Because it occurs in one of the world's driest climates, understanding its history and behavior has both scientific and practical importance. The sparse settlement of the huge (2x106 km2) area underlain by this aquifer, and the limited resources of the nations in which it occurs, result in a situation where knowledge of its origin and history is incomplete. We defined the paleodrainage channels across the entire aquifer using Shuttle Radar Topography Mission data (SRTM) and ARC/INFO watershed delineation routines. The SRTM-based streams, which are now partially covered by sand sheets and dunes, were validated by comparison to stream distribution inferred from co-registered Space-borne Imaging Radar-C/Synthetic Aperture Radar (SIR-C) data. A good correspondence between the SRTM-derived channels and the SIR-C derived channels is evident. Results indicate that there are two major paleodrainage patterns: the first extends in a NE direction from the highlands of NW Sudan towards the Kharga oasis in Egypt and feeds the underlying Nubian Aquifer Dakhla sub-basin. The second trends N-S from the highlands of northern Chad along the eastern borders of Lybia and feeds the underlying Nubian Aquifer Kufra sub-basin. We postulate that extensive recharge of the underlying Nubian aquifer must have occurred beneath the paleodrainage networks during previous wet climatic periods since the Nubian sandstone crops out across major sectors of the entire area covered by the delineated watersheds. The autochtonous recharge is supported by the presence of surrounding highlands that are largely formed of basement uplifts suggesting that these sub-basins are probably largely disconnected. This suggestion is further corroborated by the progressive increase in ages of Nubian Aquifer groundwater in the Dakhla sub-basin along the hydraulic gradient (from SW to NE). For example, the youngest 36Cl age (~50 kyr) was obtained from East Uweinat and the oldest 81Kr age (~1million yr) was obtained from Bauti-1 (Baharyia).
Uranium-series age determinations by mass spectrometric methods were done for travertines and ass... more Uranium-series age determinations by mass spectrometric methods were done for travertines and associated carbonate veins related to clastic deposits of the last glaciation (Pinedale) in the northern Yellowstone area. Dramatic variations in the hydrologic head are inferred ...
Chemical and stable isotopic compositions of groundwater samples from the Rub Al Khali (RAK) in s... more Chemical and stable isotopic compositions of groundwater samples from the Rub Al Khali (RAK) in southern Saudi Arabia were analyzed. Samples were collected from wells of variable depth (1.5–800 m) along the perimeter of the eastern half of the RAK including flowing ...
... open and productive wells tapping three types of aquifers: (1) fractured 187 basement (sample... more ... open and productive wells tapping three types of aquifers: (1) fractured 187 basement (samples: Bir Haroun, Bir Zeituna, Bir Halwagy, Bir Sahab, Bir Al ... groundwater samples from the ED (Sultan et al., 2007); and (3) data for 198 modern precipitation from Al Arish and Rafah (Fig. ...
ABSTRACT The Nubian Aquifer system of northeast Africa is one of the world's largest pota... more ABSTRACT The Nubian Aquifer system of northeast Africa is one of the world's largest potable groundwater reserves. Because it occurs in one of the world's driest climates, understanding its history and behavior has both scientific and practical importance. The sparse settlement of the huge (2x106 km2) area underlain by this aquifer, and the limited resources of the nations in which it occurs, result in a situation where knowledge of its origin and history is incomplete. We defined the paleodrainage channels across the entire aquifer using Shuttle Radar Topography Mission data (SRTM) and ARC/INFO watershed delineation routines. The SRTM-based streams, which are now partially covered by sand sheets and dunes, were validated by comparison to stream distribution inferred from co-registered Space-borne Imaging Radar-C/Synthetic Aperture Radar (SIR-C) data. A good correspondence between the SRTM-derived channels and the SIR-C derived channels is evident. Results indicate that there are two major paleodrainage patterns: the first extends in a NE direction from the highlands of NW Sudan towards the Kharga oasis in Egypt and feeds the underlying Nubian Aquifer Dakhla sub-basin. The second trends N-S from the highlands of northern Chad along the eastern borders of Lybia and feeds the underlying Nubian Aquifer Kufra sub-basin. We postulate that extensive recharge of the underlying Nubian aquifer must have occurred beneath the paleodrainage networks during previous wet climatic periods since the Nubian sandstone crops out across major sectors of the entire area covered by the delineated watersheds. The autochtonous recharge is supported by the presence of surrounding highlands that are largely formed of basement uplifts suggesting that these sub-basins are probably largely disconnected. This suggestion is further corroborated by the progressive increase in ages of Nubian Aquifer groundwater in the Dakhla sub-basin along the hydraulic gradient (from SW to NE). For example, the youngest 36Cl age (~50 kyr) was obtained from East Uweinat and the oldest 81Kr age (~1million yr) was obtained from Bauti-1 (Baharyia).
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