Use of a vertical δ18O profile to constrain hydraulic properties and recharge rates across a glacio-lacustrine unit, Nantucket Island, Massachusetts, USA

Person, Mark; Marksamer, Andee; Dugan, Brandon; Sauer, Peter E.; Brown, Kyle; Bish, David L.; Licht, Kathy J.; Willett, Mark

doi:10.1007/s10040-011-0795-1

Cited by 33 publications

(14 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For example, the fi ne-grained glaciolacustrine sediments on Nantucket Island have a low permeability (k = 1 mD) similar to that of our lowpermeability units (blue shading in Fig. 5) and also contain Holocene meteoric water (Person et al, 2012). Simple 1D advection-dispersion models showed that advection is the dominant fl uid transport mechanism within these deposits and indicate that remnants of Pleistocene glacial melt water could be fl ushed in <200 yr (Person et al, 2012).…”

Section: Modern Watersupporting

confidence: 60%

See 1 more Smart Citation

Fresh-water and salt-water distribution in passive margin sediments: Insights from Integrated Ocean Drilling Program Expedition 313 on the New Jersey Margin

et al. 2013

View full text Add to dashboard Cite

International audienceOn the New Jersey shelf (offshore North America), the presence of pore water fresher than seawater is known from a series of boreholes completed during the 1970s and 1980s. To account for this fresh water, a fi rst hypothesis involves possible present-day active dynamic connections with onshore aquifers, while a second involves meteoritic and/or sub- ice-sheet waters during periods of lowered sea level. Expedition 313 drilled three boreholes on the middle shelf, offering a unique opportunity for the internal structure of the siliciclastic system to be accessed, at scales ranging from the depositional matrix to the continental margin. This enables the stratigraphic architecture to be correlated with the spatial distribution and salinity of saturating fl uids. Expedition 313 revealed both very low salinities (<3 g/L) at depths exceeding 400 m below the seafl oor and evidence for a multilayered reservoir organization, with freshand/ or brackish-water intervals alternating vertically with salty intervals. In this study we present a revised distribution of the salinity beneath the middle shelf. Our observations suggest that the processes controlling salinity are strongly infl uenced by lithology, porosity, and permeability. Saltier pore waters generally occur in coarse-grained intervals and fresher pore waters occur in fi ne-grained intervals. The transition from fresher to saltier intervals is often marked by cemented horizons that probably act as permeability barriers. In the lowermost parts of two holes, the salinity varies independently of lithology, suggesting different mechanisms and/or sources of salinity. We present an interpretation of the sedimentary facies distribution, derived from core, logs, and seismic profi le analyses, that is used to discuss the marginscale two-dimensional reservoir geometry and permeability distribution. These proposed geometries are of primary importance when considering the possible pathways and emplacement mechanisms for the fresh and salty water below the New Jersey shelf

show abstract

Section: Modern Watersupporting

confidence: 60%

“…5) and also contain Holocene meteoric water (Person et al, 2012). Simple 1D advection-dispersion models showed that advection is the dominant fl uid transport mechanism within these deposits and indicate that remnants of Pleistocene glacial melt water could be fl ushed in <200 yr (Person et al, 2012).…”

Section: Modern Watermentioning

confidence: 98%

Fresh-water and salt-water distribution in passive margin sediments: Insights from Integrated Ocean Drilling Program Expedition 313 on the New Jersey Margin

et al. 2013

View full text Add to dashboard Cite

show abstract

“…They found that sea‐level changes and subsequent meteoric recharge alone could not account for the observed distribution of freshwater. By imposing ice sheet loading and recharge beneath pro‐glacial lakes, they were able to drive freshwater far offshore (Person et al. 2011).…”

Section: Model Resultsmentioning

confidence: 99%

Models of ice‐sheet hydrogeologic interactions: a review

et al. 2012

View full text Add to dashboard Cite

This study reviews the state-of-the-art and promising pathways to advance hydrologic models of groundwater flow systems and related transport processes in response to transient glacial loading. We also discuss the utility of hydrologic and geochemical data sets as a means of providing ground truth for these models. The paleohydrologic models presented herein should be used as analogues to assess high-level nuclear waste repository stability in response to future episodes of glaciations in countries such as Canada, Sweden, and Switzerland. The next generation of fully coupled ice-sheet-aquifer models may also be of use in assessing rates of ice sheet denudation on Greenland and Antarctica in response to global warming. However, significant uncertainty exists in paleoclimatic forcing, paleohydrologic boundary conditions, and effective basin-scale petrophysical parameters. Thus, model results must be viewed with some caution. Model results from studies reviewed herein suggest that during the last glacial maximum, recharge rates across glaciated basin margins increased by as much as 2-6 times modern levels. Paleohydrologic models predict that as ice sheets overran sedimentary basin margins, glacial melt water penetrated to depths of up to hundreds of meters. Recent ice-sheet models that incorporated the effects of groundwater flow suggest that the presence of a 1-10 mm film of water at the glacial bed can increase basal ice sliding rates by up to 4 orders of magnitude. No firm theoretical basis exists for coupling ice sheet and subsurface hydrogeologic models nor the effects of permafrost on hydraulic conductivity. These issues could be resolved, to some degree, by additional careful experimental studies. Analysis of fluid pressures and flow rates beneath modern ice sheets using geochemical tracers would help to reduce the uncertainty regarding suitable hydrogeologic boundary conditions, parameterization of poromechanical coupling, and transport processes. Glacial geologists should work closely with modelers to provide better constraints on model boundary conditions.

show abstract

“…From Post et al (2013), it is evident that offshore freshwater storages as long as this do exist. Indeed among the cases they cite, three of them have salinities (TDS) smaller than 2.5 g/L (equivalent to an EC = 5,000 μS/cm) up to 100 km from the coastline-Nantucket Island, USA, Person et al (2012), Beaufort MacKenzie Basin, USA (Grasby et al 2009), Suriname (Groen et al 2000), and one has a TDS smaller than 5 g/L up to 100 km from the coastline, New Jersey (Hataway et al 1979;Malone et al 2002). All are proven by direct observational data.…”

Section: Comparison With Other Casesmentioning

confidence: 99%

Why seawater intrusion has not yet occurred in the Kaluvelli-Pondicherry basin, Tamil Nadu, India

Vincent

Violette

2017

Hydrogeol J

View full text Add to dashboard Cite

Worldwide, coastal aquifers are threatened by seawater intrusion. The threat is greatest when aquifers are overexploited or when recharge is low due to a semi-arid or arid climate. The Kaluvelli-Pondicherry sedimentary basin in Tamil Nadu (India) presents both these characteristics. Groundwater levels in the Vanur aquifer can reach 50 m below sea level at less than 20 km inland. This groundwater depletion is due to an exponential increase in extraction for irrigation over 35 years. No seawater intrusion has yet been detected, but a sulphate-rich mineralization is observed, the result of upward vertical leakage from the underlying Ramanathapuram aquifer. To characterize the mechanisms involved, and to facilitate effective water management, hydrogeological numerical modelling of this multi-layered system has been conducted. Existing and acquired geological and hydrodynamic data have been applied to a quasi-3D hydrogeological model, NEWSAM. Recharge had been previously quantified through the intercomparison of hydrological models, based on climatological and surface-flow field measurements. Sensitivity tests on parameters and boundary conditions associated with the sea were performed. The resulting water balances for each aquifer led to hypotheses of (1) an offshore fresh groundwater stock, and (2) a reversal and increase of the upward leakage from the Ramanathapuram aquifer, thus corroborating the hypothesis proposed to explain geochemical results of the previous study, and denying a seawater intrusion. Palaeo-climate review supports the existence of favourable hydro-climatological conditions to replenish an offshore groundwater stock of the Vanur aquifer in the past. The extent of this fresh groundwater stock was calculated using the Kooi and Groen method.

show abstract

Use of a vertical δ18O profile to constrain hydraulic properties and recharge rates across a glacio-lacustrine unit, Nantucket Island, Massachusetts, USA

Cited by 33 publications

References 31 publications

Fresh-water and salt-water distribution in passive margin sediments: Insights from Integrated Ocean Drilling Program Expedition 313 on the New Jersey Margin

Fresh-water and salt-water distribution in passive margin sediments: Insights from Integrated Ocean Drilling Program Expedition 313 on the New Jersey Margin

Models of ice‐sheet hydrogeologic interactions: a review

Why seawater intrusion has not yet occurred in the Kaluvelli-Pondicherry basin, Tamil Nadu, India

Contact Info

Product

Resources

About