Investigation of paleoclimate signatures in Sfax deep groundwater (Southeastern Tunisia) using environmental isotopes and noble gases

We have studied environmental isotopes and noble gases in groundwater samples from various locations in the Great Hungarian Plain along two selected hydrogeological cross-sections of ca 100km. The 14C groundwater ages were corrected hydrochemically and compared with age information derived from excess helium due to 4He from α-decay of U and Th and their daughter nuclides within the aquifer and to He accumulation from the crustal (and mantle) He flux. In correcting the 14C groundwater ages, we considered carbonate dissolution under open and closed system conditions in the infiltration areas. Non-radioactive reduction of the 14C/12C isotope ratio also plays an important role due to the addition of “dead” carbon species to groundwater along its subsurface pathway. High (corrected) 14C ages, which fall into the last global cold period, are supported by significantly lower heavy stable isotope values as well as lower temperatures derived from the noble gases Ne, Ar, Kr and Xe.

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Environmental isotopes and noble gas ages of the deep groundwater with coupled flow modelling in the Baltic artesian basin

Lithuanian Journal of Physics ◽

10.3952/physics.v61i1.4407 ◽

2021 ◽

Vol 61 (1) ◽

Author(s):

R. Mokrik ◽

V. Samalavičius ◽

M. Gregorauskas ◽

M. Bujanauskas

Keyword(s):

Noble Gas ◽

Sedimentary Cover ◽

Regional Scale ◽

Environmental Isotopes ◽

Age Dating ◽

Coupled Flow ◽

Deep Groundwater ◽

Artesian Basin ◽

Deep Aquifers ◽

The Baltic

In this study, modelled groundwater actual flow times in intermediate and deep aquifers, covered by regional scale impermeable aquitards, were compared with 4He and 81Kr age dating results. To improve the reliability of the steady state 3D groundwater flow model, the isotopic ages of deep groundwater were compared to the MODPATH modelled travel times. The highest helium values in groundwater reservoirs coincide with fault zones in the crystalline basement and sedimentary cover near Rapakivi granite massifs. Insights into isotope-geochemical anomalies of the Baltic Artesian Basin intermediate and deep groundwater support their main distribution peculiarities in the flow path towards the Baltic Sea coast lowland and seabed depression as the regional groundwater discharge area.

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Tracing groundwater recharge conditions based on environmental isotopes and noble gases, Lom depression, Bulgaria

Journal of Hydrology Regional Studies ◽

10.1016/j.ejrh.2019.100611 ◽

2019 ◽

Vol 24 ◽

pp. 100611

Author(s):

Marianna Túri ◽

Mihály Molnár ◽

Tatiana Orehova ◽

Aglaida Toteva ◽

Vladimir Hristov ◽

...

Keyword(s):

Groundwater Recharge ◽

Noble Gases ◽

Environmental Isotopes

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Environmental isotopes and noble gases in the deep aquifer system of Kazan Trona Ore Field, Ankara, central Turkey and links to paleoclimate

Quaternary Research ◽

10.1016/j.yqres.2012.12.001 ◽

2013 ◽

Vol 79 (2) ◽

pp. 292-303 ◽

Cited By ~ 7

Author(s):

Sebnem Arslan ◽

Hasan Yazicigil ◽

Martin Stute ◽

Peter Schlosser

Keyword(s):

North Africa ◽

Noble Gases ◽

Noble Gas ◽

Environmental Isotopes ◽

Climatic Conditions ◽

Deep Aquifer ◽

Aquifer System ◽

Ground Temperatures ◽

Groundwater Samples ◽

Central Turkey

AbstractEnvironmental isotopes and noble gases in groundwater samples from the Kazan Trona Ore Field are studied to establish the temperature change between the Holocene and the late Pleistocene. Noble gas temperatures (NGTs) presented in this study add an important facet to the global paleotemperature map in the region between Europe and North Africa. The groundwater system under investigation consists of three different aquifers named shallow, middle and deep in which δ18O and δ2H vary from − 8.10‰ to − 12.80‰ and from − 60.89‰ to − 92.60‰ VSMOW, respectively. The average isotopic depletion between unconfined and confined parts of the system is − 2.5‰ in δ18O and − 20‰ in δ2H. It is not possible to explain this depletion solely with the elevation effect. Recharge temperatures derived from dissolved atmospheric noble gases reflect the current average yearly ground temperatures (13°C) for samples collected near the recharge area but are 3 to 8°C lower than today's temperatures in the deep aquifer system. Low 14C activities and high He excesses in the confined parts of the aquifer system suggest that the water in the deep aquifer was recharged during the last Pleistocene under considerably cooler climatic conditions.

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Case study: methane gas in a groundwater system located in a dolerite ring structure in the Karoo Basin; South Africa

South African Journal of Geology ◽

10.25131/sajg.122.0025 ◽

2019 ◽

Vol 122 (3) ◽

pp. 357-368 ◽

Cited By ~ 1

Author(s):

D. Hohne ◽

F. de Lange ◽

S. Esterhuyse ◽

B. Sherwood Lollar

Keyword(s):

Meteoric Water ◽

Shallow Groundwater ◽

Environmental Isotopes ◽

Ring Structure ◽

Deep Groundwater ◽

Methane Gas ◽

Karoo Basin ◽

Close Proximity ◽

Local Municipality

Abstract In the past few years numerous assumptions were made on groundwater in the Karoo Basin and related shale gas development, but not many baseline studies were conducted on groundwater and on boreholes where methane currently occurs. This article focuses on one of these boreholes (BHA) in the Ubuntu Local Municipality area, located close to a dolerite ring structure, which is releasing methane gas. Water samples were analysed for macro and trace elements, environmental isotopes and methane concentrations. Chemical analyses results indicate that groundwater at this borehole may be a mixture between deep groundwater, shallow groundwater and meteoric water. A rise in the groundwater level and subsequent flowing artesian conditions that was observed, support the theory that mixing between deeper groundwater from the Ecca Group and shallower water from the Beaufort Group is taking place. These water level reactions could be due to possible seismic activity within close proximity to the dolerite ring structure and/or due to recharge and interflow to BHA.

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