81Kr/85Kr-Dating of thermal groundwaters in the Upper Jurassic (Molasse Basin)

Heidinger, Michael; Eichinger, Florian; Purtschert, Roland; Mueller, Peter; Zappala, Jake; Wirsing, Gunther; Geyer, Tobias; Fritzer, Thomas; Groß, Doris (2019). 81Kr/85Kr-Dating of thermal groundwaters in the Upper Jurassic (Molasse Basin). Grundwasser, 24(4), pp. 287-294. Springer 10.1007/s00767-019-00431-0

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81Kr (half-life 229,000 years) is an ideal tracer for old groundwater. The Upper Jurassic rock in the deep Molasse Basin is an outstanding geothermal groundwater reservoir (with temperatures up to 140 °C). However, due to the complex groundwater evolution (ion and isotope exchange, gas flux, etc.), comprehensive hydrogeological studies completed to date, including 14C‑DIC and He isotopes, could not resolve the recharge dynamics and residence times. Nine geothermal wells were therefore sampled for 81Kr/85Kr employing the laser-based atom trap tracer analysis technique (ATTA). In the western and central basin, the results reveal predominant groundwater recharge during the last glacial period with one sample influenced by infiltration during the earlier glacial period. Recharge signatures and 81Kr-model-ages fit very well to subglacial recharge with cross-formational flow through the sedimentary cover (600 to >3000 m deep). In the eastern basin, the results point to the Cromerian complex, indicating a slower flow system with less influence from recharge during glacial periods.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute > Climate and Environmental Physics

UniBE Contributor:

Purtschert, Roland

Subjects:

500 Science > 530 Physics

ISSN:

1430-483X

Publisher:

Springer

Language:

German

Submitter:

Doris Rätz

Date Deposited:

30 Jun 2021 16:42

Last Modified:

05 Dec 2022 15:51

Publisher DOI:

10.1007/s00767-019-00431-0

Uncontrolled Keywords:

Molasse basin Old groundwater Krypton Isotope Dating Recharge Cross-formational flow ATTA 81Kr 85Kr

BORIS DOI:

10.48350/157195

URI:

https://boris.unibe.ch/id/eprint/157195

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