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Stable isotope evidence for the hydrogeological characteristics of clay-rich till in northern East Anglia

K. M. Hiscock, M. A. George and P. F. Dennis
Stable isotope evidence for the hydrogeological characteristics of clay-rich till in northern East Anglia
Quarterly Journal of Engineering Geology and Hydrogeology (May 2011) 44 (2): 173-189

Abstract

The intrinsic vulnerability of the Chalk aquifer in East Anglia in eastern England to surface-derived contamination is dependent on the nature and juxtaposition of overlying Quaternary deposits. The study presented here is a direct investigation of the physical characteristics and pore water isotope composition of the glacial deposits found overlying the Chalk at five drilled locations in north Norfolk. The pore water isotopic composition demonstrated a range of delta (super 18) O values from -8.13 to -6.47 per mil, similar to the range for Chalk groundwater in the area of -8.18 to -7.01 per mil. A lithology-dependent model is developed that recognizes the presence of isotopically depleted palaeowater of late Pleistocene origin contained within layers of clay-rich till, adjacent to pore water containing modern meteoric water within layers of sand-rich till. The presence of (weathered) vertical fractures and intercalated lenses of sand- and gravel-rich layers is inferred to explain the occurrence of isotopically enriched water within the general mass of clay-rich till. It is apparent that groundwater movement in the heterogeneous lodgement till is controlled by advection in the more permeable sand-rich layers, whereas in the mass of clay-rich till, diffusion is more dominant. At one confined site, the observed pore water isotopic profile is modelled as having developed by downward diffusion of modern meteoric water during the past 5-10 ka.


ISSN: 1470-9236
EISSN: 2041-4803
Serial Title: Quarterly Journal of Engineering Geology and Hydrogeology
Serial Volume: 44
Serial Issue: 2
Title: Stable isotope evidence for the hydrogeological characteristics of clay-rich till in northern East Anglia
Affiliation: University of East Anglia, School of Environmental Sciences, Norwich, United Kingdom
Pages: 173-189
Published: 201105
Text Language: English
Publisher: Geological Society of London, London, United Kingdom
References: 74
Accession Number: 2011-048425
Categories: HydrogeologyIsotope geochemistry
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables, geol. sketch map
N52°25'00" - N53°00'00", E00°10'00" - E01°45'00"
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data from The Geological Society, London, London, United Kingdom
Update Code: 201127
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