Red Sea Rifting Controls on Groundwater Reservoir Distribution: Constraints from Geophysical, Isotopic, and Remote Sensing Data
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Date
2008-10
Authors
Sturchio, Neil C.
Sagin, Jay
Becker, Richard H.
Ahmed, Mohamed
Journal Title
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Abstract
Highly productive wells in the Central
Eastern Desert of Egypt are tapping groundwater
in subsided blocks of Jurassic to
Cretaceous sandstone (Taref Formation of
the Nubian Sandstone Group) and Oligocene
to Miocene sandstone (Nakheil Formation),
now occurring beneath the Red Sea coastal
plain and within the proximal basement complex.
Aquifer development is related to Red
Sea rifting: (1) rifting was accommodated by
vertical extensional displacement on preexisting
NW-SE– to N-S–trending faults forming
a complex array of half-grabens and asymmetric
horsts; and (2) subsided blocks escaped
erosion accompanying the Red Sea–related
uplift. Subsided blocks were identifi ed and
verifi ed using satellite data, geologic maps,
and fi eld and geophysical investigations. Interpretations
of very low frequency (VLF)
measurements suggest the faults acted as
conduits for ascending groundwater from the
subsided aquifers. Stable isotopic compositions
(δD: –19.3‰ to –53.9‰; δ18O: –2.7‰ to
–7.1‰) of groundwater samples from these
aquifers are interpreted as mixtures of fossil
(up to 70%) and modern (up to 65%) precipitation.
Groundwater volumes in subsided
blocks are large; within the Central Eastern
Desert basement complex alone, they are estimated
at 3 × 109 m3 and 10 × 109 m3 for the
Nakheil and Taref Formations, respectively.
Results highlight the potential for identifying
similar rift-related aquifer systems along
the Red Sea–Gulf of Suez system, and in rift
systems elsewhere. An understanding of the
distribution of Red Sea rift–related aquifers
and modern recharge contributions to these
aquifers could assist in addressing the rising
demands for fresh water supplies and water
scarcity issues in the region
Description
Keywords
Groundwater Reservoir Distribution
Citation
Neil C Sturchio, Jay Sagin, Richard H Becker, Mohamed Ahmed; 2008; Red Sea Rifting Controls on Groundwater Reservoir Distribution: Constraints from Geophysical, Isotopic, and Remote Sensing Data