Isotopic and noble gas study of Chalk groundwater in the London Basin, England

Dennis, Frank; Andrews, John N.; Parker, Andrew; Poole, Jason; Wolf, Marco

doi:10.1016/s0883-2927(97)00046-2

Cited by 27 publications

(17 citation statements)

References 13 publications

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“…Despite the low noble gas temperatures and Late Pleistocene ages, very few isotopically depleted waters have been documented in the Chalk aquifer. This may be a function of mixing of waters between fissures and the chalk matrix as demonstrated by Dennis et al. (1997), who were able to calculate reasonable 14 C ages for groundwaters in the Chalk aquifer assuming a diffusion model, which incorporates mixing of waters with older groundwaters from the aquifer matrix.…”

Section: Pleistocene Recharge To European Sedimentary Basinsmentioning

confidence: 99%

Glacial impacts on hydrologic processes in sedimentary basins: evidence from natural tracer studies

McIntosh¹,

Schlegel²,

Person³

2011

Geofluids

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This study reviews and synthesizes the results from geochemical and isotopic case studies across Europe, North America, Antarctica, and Greenland to evaluate the effects of Pleistocene glaciation on continental-scale groundwater circulation in sedimentary basins. The most effective studies, in terms of delineating high-resolution records of paleorecharge to aquifers, combine solute chemistry, stable isotopes of water, age tracers, and dissolved noble gases. Some of the lowest d 18 O values ()22&), and noble gas temperatures (0°C), and high excess air concentrations were found in confined groundwaters in northern Estonia, likely derived from Scandinavian Ice Sheet subglacial recharge. These results are consistent with groundwater systems in North America that were recharged beneath the Laurentide Ice Sheet. Late Pleistocene precipitation may have also been an important source of recharge, as indicated by low-temperature, isotopically enriched groundwaters in several basins. Detectable age gaps have been observed in several aquifer systems in North America and Europe, likely caused by a hiatus of groundwater recharge in areas covered by permafrost during the Last Glacial Maximum (10-21 ka). Aquifers that were not covered by ice sheets or permafrost contain continuous records of Pleistocene to Holocene recharge with variable d 18 O values and low paleotemperatures (4-9°C lower than today). The maximum depth of glacial meltwater penetration into sedimentary basins is approximately 50-1000 m. Infiltration of dilute meltwaters dissolved large quantities of halite in evaporite-bearing basins. The presence of clay-rich glacial deposits and bedrock confining units enhanced the storage of meltwaters within low-permeability sediments and limited flushing of paleowaters in underlying aquifers. These results demonstrate the importance of continental glaciation as a driver for basinal-scale fluid and solute transport and have implications for long-term storage of radioactive waste and carbon dioxide at depth in high-latitude sedimentary basins.

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Section: Pleistocene Recharge To European Sedimentary Basinsmentioning

confidence: 99%

Glacial impacts on hydrologic processes in sedimentary basins: evidence from natural tracer studies

McIntosh¹,

Schlegel²,

Person³

2011

Geofluids

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“…The finding that extratropical study sites usually have

\frac{{((), R / P)}_{winter}}{{((), R / P)}_{summer}}

values exceeding one (i.e., δ G < δ P (annual) ) even for studies that do not account for snowpack evolution (most works compiled in Table ) strengthens the conclusion that recharge is often biased to cold‐season precipitation. The impact of evaporation on δ 18 O during infiltration may also affect some groundwater isotope compositions, though at a global‐scale most groundwaters have d‐excess values similar to precipitation (implying partial evaporation of infiltrating waters to be of lesser importance; section ; Figure ). Multiple studies suggest that evaporative isotope effects have minimal impact on isotopic compositions of recharge (e.g., Dennis et al, ; Geirnaert et al, ; Mountain et al, ). Yet other works identify groundwater δ 18 O and δ 2 H values that plot “below” meteoric water lines in δ 18 O‐δ 2 H space, implying evaporative isotope effects may be important (especially in certain arid areas; e.g., Fontes & Edmunds, ).…”

Section: Seasonal Biases In Groundwater Rechargementioning

confidence: 99%

Global Isotope Hydrogeology―Review

Jasechko

2019

Reviews of Geophysics

230

124

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Groundwater 18O/16O, 2H/1H, 13C/12C, 3H, and 14C data can help quantify molecular movements and chemical reactions governing groundwater recharge, quality, storage, flow, and discharge. Here, commonly applied approaches to isotopic data analysis are reviewed, involving groundwater recharge seasonality, recharge elevations, groundwater ages, paleoclimate conditions, and groundwater discharge. Reviewed works confirm and quantify long held tenets: (i) that recharge derives disproportionately from wet season and winter precipitation; (ii) that modern groundwaters comprise little global groundwater; (iii) that “fossil” (>12,000‐year‐old) groundwaters dominate global aquifer storage; (iv) that fossil groundwaters capture late‐Pleistocene climate conditions; (v) that surface‐borne contaminants are more common in younger groundwaters; and (vi) that groundwater discharges generate substantial streamflow. Groundwater isotope data are disproportionately common to midlatitudes and sedimentary basins equipped for irrigated agriculture, but less plentiful across high latitudes, hyperarid deserts, and equatorial rainforests. Some of these underexplored aquifer systems may be suitable targets for future field testing.

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“…In United Kingdom, the Chalk aquifers were studied by Hiscock et al [32] in the Norfolk area (eastern England), by Dennis et al [33] in the London Basin (SE England) and by Elliot et al [34] in the London and the adjacent Berkshire Basin (east of the London Basin). The geology consists of Cretaceous Chalk overlain by Tertiary clastic deposits with a thickness of more than 400 m in the Norfolk area and up to 250 in the London Basin.…”

Section: London Basinmentioning

confidence: 99%