Dissolved noble gases and stable isotopes as tracers of prefential fluid flow along faults in the Lower Rhine Embayment, Germany

V.F. Bense, L.P. Gumm, P. Dennis, N. Hiscock, N. Cremer, S. Simon

Research output: Contribution to journalArticleAcademicpeer-review

10 Citations (Scopus)

Abstract

Groundwater in shallow unconsolidated sedimentary aquifers close to the Bornheim fault in the Lower Rhine Embayment (LRE), Germany, has relatively low d2H and d18O values in comparison to regional modern groundwater recharge, and 4He concentrations up to 1.7¿×¿10-4 cm3 (STP) g–1¿±¿2.2 % which is approximately four orders of magnitude higher than expected due to solubility equilibrium with the atmosphere. Groundwater age dating based on estimated in situ production and terrigenic flux of helium provides a groundwater residence time of ~107 years. Although fluid exchange between the deep basal aquifer system and the upper aquifer layers is generally impeded by confining clay layers and lignite, this study’s geochemical data suggest, for the first time, that deep circulating fluids penetrate shallow aquifers in the locality of fault zones, implying that sub-vertical fluid flow occurs along faults in the LRE. However, large hydraulic-head gradients observed across many faults suggest that they act as barriers to lateral groundwater flow. Therefore, the geochemical data reported here also substantiate a conduit-barrier model of fault-zone hydrogeology in unconsolidated sedimentary deposits, as well as corroborating the concept that faults in unconsolidated aquifer systems can act as loci for hydraulic connectivity between deep and shallow aquifers. The implications of fluid flow along faults in sedimentary basins worldwide are far reaching and of particular concern for carbon capture and storage (CCS) programmes, impacts of deep shale gas recovery for shallow groundwater aquifers, and nuclear waste storage sites where fault zones could act as potential leakage pathways for hazardous fluids.
Original languageEnglish
Pages (from-to)99-108
JournalHydrogeology Journal
Volume24
Issue number1
DOIs
Publication statusPublished - 2016

Fingerprint Dive into the research topics of 'Dissolved noble gases and stable isotopes as tracers of prefential fluid flow along faults in the Lower Rhine Embayment, Germany'. Together they form a unique fingerprint.

Cite this