Using ⁸¹ Kr and noble gases to characterize and date groundwater and brines in the Baltic Artesian Basin on the one-million-year timescale

Gerber, Christoph; Vaikmäe, Rein; Aeschbach, Werner; Babre, Alise; Jiang, Wei; Leuenberger, Markus; Lu, Zheng-Tian; Mokrik, Robert; Müller, Peter; Raidla, Valle; Saks, Tomas; Waber, H. Niklaus; Weissbach, Therese; Zappala, Jake C.; Purtschert, Roland (2017). Using ⁸¹ Kr and noble gases to characterize and date groundwater and brines in the Baltic Artesian Basin on the one-million-year timescale. Geochimica et cosmochimica acta, 205, pp. 187-210. Elsevier Science 10.1016/j.gca.2017.01.033

[img] Text
gerber17gca.pdf - Published Version
Restricted to registered users only
Available under License Publisher holds Copyright.

Download (2MB) | Request a copy

Analyses for ⁸¹Kr and noble gases on groundwater from the deepest aquifer system of the Baltic Artesian Basin (BAB) were performed to determine groundwater ages and uncover the flow dynamics of the system on a timescale of several hundred thousand years. We find that the system is controlled by mixing of three distinct water masses: Interglacial or recent meteoric water (δ⁸¹O ≈ −10.4‰) with a poorly evolved chemical and noble gas signature, glacial meltwater (δ⁸¹O ⩽ −18‰) with elevated noble gas concentrations, and an old, high-salinity brine component (δ⁸¹O ⩾ −4.5‰, ⩾ 90 g Cl−/L) with strongly depleted atmospheric noble gas concentrations. The 81Kr measurements are interpreted within this mixing framework to estimate the age of the end-members. Deconvoluted ⁸¹Kr ages range from 300 ka to 1.3 Ma for interglacial or recent meteoric water and glacial meltwater. For the brine component, ages exceed the dating range of the ATTA-3 instrument of 1.3 Ma. The radiogenic noble gas components ⁴He∗ and ⁴⁰Ar∗ are less conclusive but also support an age of > 1 Ma for the brine. Based on the chemical and noble gas concentrations and the dating results, we conclude that the brine originates from evaporated seawater that has been modified by later water–rock interaction. As the obtained tracer ages cover several glacial cycles, we discuss the impact of the glacial cycles on flow patterns in the studied aquifer system.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute > Climate and Environmental Physics
10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR)
08 Faculty of Science > Institute of Geological Sciences

UniBE Contributor:

Gerber, Christoph; Leuenberger, Markus; Waber, Niklaus and Purtschert, Roland

Subjects:

500 Science > 550 Earth sciences & geology
500 Science > 530 Physics

ISSN:

0016-7037

Publisher:

Elsevier Science

Language:

English

Submitter:

Doris Rätz

Date Deposited:

27 Apr 2017 14:57

Last Modified:

28 Jun 2017 12:59

Publisher DOI:

10.1016/j.gca.2017.01.033

BORIS DOI:

10.7892/boris.98158

URI:

https://boris.unibe.ch/id/eprint/98158

Actions (login required)

Edit item Edit item
Provide Feedback