Groundwater dating with dissolved organic radiocarbon: A promising approach in carbonate aquifers

Heine, Florian; Einsiedl, Florian

doi:10.1016/j.apgeochem.2020.104827

Cited by 9 publications

(15 citation statements)

References 51 publications

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“…The concept of subglacial recharge and cross-formational flow in the south-west of the SGMB (lake Constance region) and ion-exchange of paleo-water with an assumed northwards flow direction to the draining river Danube by [32,57] was recently supported by groundwater dating results derived from 81 Kr [44] and 14 C DOC [58].…”

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confidence: 99%

Hydrochemical Zoning and Chemical Evolution of the Deep Upper Jurassic Thermal Groundwater Reservoir Using Water Chemical and Environmental Isotope Data

Heine

Zoßeder

Einsiedl

2021

Water

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A comprehensive hydrogeological understanding of the deep Upper Jurassic carbonate aquifer, which represents an important geothermal reservoir in the South German Molasse Basin (SGMB), is crucial for improved and sustainable groundwater resource management. Water chemical data and environmental isotope analyses of δD, δ18O and 87Sr/86Sr were obtained from groundwater of 24 deep Upper Jurassic geothermal wells and coupled with a few analyses of noble gases (3He/4He, 40Ar/36Ar) and noble gas infiltration temperatures. Hierarchical cluster analysis revealed three major water types and allowed a hydrochemical zoning of the SGMB, while exploratory factor analyses identified the hydrogeological processes affecting the water chemical composition of the thermal water. Water types 1 and 2 are of Na-[Ca]-HCO3-Cl type, lowly mineralised and have been recharged under meteoric cold climate conditions. Both water types show 87Sr/86Sr signatures, stable water isotopes values and calculated apparent mean residence times, which suggest minor water-rock interaction within a hydraulically active flow system of the Northeastern and Southeastern Central Molasse Basin. This thermal groundwater have been most likely subglacially recharged in the south of the SGMB in close proximity to the Bavarian Alps with a delineated northwards flow direction. Highly mineralised groundwater of water type 3 (Na-Cl-HCO3 and Na-Cl) occurs in the Eastern Central Molasse Basin. In contrast to water types 1 and 2, this water type shows substantial water-rock interaction with terrestrial sediments and increasing 40Ar/36Ar ratios, which may also imply a hydraulic exchange with fossil formation waters of overlying Tertiary sediments.

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confidence: 99%

Hydrochemical Zoning and Chemical Evolution of the Deep Upper Jurassic Thermal Groundwater Reservoir Using Water Chemical and Environmental Isotope Data

Heine

Zoßeder

Einsiedl

2021

Water

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“…where H is the GW recharge elevation (m), δ 18 O GTW is the isotopic composition of the sample collected at the GW sampling site, δ 18 O r is the isotopic composition of the sample of precipitation at the reference site, gradδ 18 O is the average gradient in the low-latitude southern region of China (−0.3‰/100 m) [14], and H r is the ground elevation at the GW reference site (i.e., the Nanjing Observation Station of the GNIP) (26 m). The mixing relationship between the GTW and the cold GW in the study area was examined using a binary mixing model based on Sr and 87 Sr/ 86 Sr, as shown below [15][16][17][18] The age of the GTW in Tangquan was determined by 14 C using the following equation [19]:…”

Section: Methodsmentioning

confidence: 99%

Recharge Sources and Genetic Model of Geothermal Water in Tangquan, Nanjing, China

Yu²,

Luo

2021

Sustainability

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This paper introduces a method to study the origin of geothermal water by analysis of hydrochemistry and isotopes. In addition, the genetic mechanism of geothermal water (GTW) is revealed. The study of the origin of geothermal water is useful for the sustainability of geothermal use. As an example, Tangquan is abundant in GTW resources. Elucidating the recharge sources and formation mechanism of the GTW in this area is vitally important for its scientific development. In this study, the GTW in Tangquan was systematically investigated using hydrochemical and isotopic geochemical analysis methods. The results show the following. The GTW and shallow cold water in the study area differ significantly in their hydrochemical compositions. The geothermal reservoir has a temperature ranging from 63 to 75 °C. The GTW circulates at depths of 1.8–2.3 km. The GTW is recharged by the infiltration of meteoric water at elevations of 321–539 m and has a circulation period of approximately 2046–6474 years. The GTW becomes mixed with the shallow cold karst water at a ratio of approximately 4–26% (cold water) during the upwelling process. In terms of the cause of its formation, the geothermal system in the study area is, according to analysis, of the low-medium-temperature convective type. This geothermal system is predominantly recharged by precipitation that falls in the outcropping carbonate area within the Laoshan complex anticline and is heated by the terrestrial heat flow in the area. The geothermal reservoir is composed primarily of Upper Sinian dolomite formations, and its caprock is made up of Cambrian, Cretaceous, and Quaternary formations. Through deep circulation, the GTW migrates upward along channels formed from the convergence of northeast–east- and north–west-trending faults and is mixed with the shallow cold water, leading to geothermal anomalies in the area.

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“…The western and northern rather shallow parts of the Molasse Basin show a widespread heterogenous Tertiary overlay directly on the Upper Jurassic carbonates. Following, it may be assumed, that the terrigenous sediments are partly in hydraulic contact with the Upper Jurassic aquifer system in this area [44].…”

Section: Geologic Description Of the Sgmbmentioning

confidence: 99%

Section: Hydrogeological Situation Of the Upper Jurassic Aquifermentioning

confidence: 99%

“…The majority of shallow groundwaters at the western and northern margin of the SGMB are mostly of the Ca-[Mg]-HCO3 type and were recharged under predominantly warm climate conditions [8,9,44]. Generally, they include considerable amounts of tritium and radiocarbon (DIC) which indicate modern, sub-modern and medium old groundwater ages [9,35,44,61,62]. Some groundwaters in the proximity of the river Danube, especially to the north-east of the basin, deviated from this and show similar hydrochemical characteristics to groundwaters from the central SGMB.…”

Section: Hydrogeological Situation Of the Upper Jurassic Aquifermentioning

confidence: 99%

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Transformational Geothermal Fluids in the Upper Jurassic Carbonate Reservoir of the South German Molasse Basin

Schneider¹,

Heine²,

Heidinger³

et al. 2022

Preprint

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The hydrochemical composition of the Upper Jurassic groundwaters in the South German Mo-lasse Basin (SGMB) indicates a heterogeneous and varying hydrogeochemical evolution, which contradicts previous flow model concepts. For this study, the data of 88 Tertiary, Cretaceous and Upper Jurassic groundwater samples were investigated for hydrochemical elements, 2H/18O-H2O isotopes, 87Sr/86Sr ratios as well as δ11B values. In addition, the geochemical composition, 87Sr/86Sr and δ11B values were analysed from depth-oriented Upper Jurassic rock samples to delineate water-rock interactions in the aquifer systems. Slightly elevated 87Sr/86Sr ratios of the carbonates compared to the typical signatures of marine Upper Jurassic carbonates indicate a synsedimentary radiogenic influence due to the erosion of the adjacent Bohemian Massif. However, these values cannot explain the significant higher Sr-isotope fingerprint of the groundwaters in the central SGMB. Different water types occur in the Upper Jurassic aquifer, primarily distinguished by the dominant cations, calcium or sodium with subclasses of the major anions. The calcium-dominated groundwaters occur mainly at the western and northern margins of the SGMB. The sodi-um-dominated ion exchange groundwaters instead dominate in the central and eastern SGMB. With increasing strontium content, the 87Sr/86Sr ratios of the Upper Jurassic groundwater samples either indicate a strontium uptake by carbonate of the host rocks, or a prevailing radiogenic sig-nature. This implies a basic interaction with terrestrial or marine Tertiary sediments. The results illustrate a downward transformational fluid flow systematic via the thick Tertiary sediment cover into the Upper Jurassic carbonate formation in the SGMB, highlighting a new understanding on the evolution of the Upper Jurassic groundwaters and a basin-wide recharge mechanism.

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Groundwater dating with dissolved organic radiocarbon: A promising approach in carbonate aquifers

Cited by 9 publications

References 51 publications

Hydrochemical Zoning and Chemical Evolution of the Deep Upper Jurassic Thermal Groundwater Reservoir Using Water Chemical and Environmental Isotope Data

Hydrochemical Zoning and Chemical Evolution of the Deep Upper Jurassic Thermal Groundwater Reservoir Using Water Chemical and Environmental Isotope Data

Recharge Sources and Genetic Model of Geothermal Water in Tangquan, Nanjing, China

Transformational Geothermal Fluids in the Upper Jurassic Carbonate Reservoir of the South German Molasse Basin

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