EGU23-6006, updated on 06 May 2023
https://doi.org/10.5194/egusphere-egu23-6006
EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Last ice sheet recession and landscape emergence above sea level in east central Sweden, evaluated using 14C produced in situ in quartz

Bradley W. Goodfellow1, Arjen P. Stroeven2,3, Alexander Lewerentz1, Kristina Hippe4, Jakob Heyman5, Nathaniel A. Lifton6,7, Marc W. Caffee6,7, and Jens-Ove Näslund8
Bradley W. Goodfellow et al.
  • 1Geological Survey of Sweden, Lund, Sweden (bradley.goodfellow@sgu.se)
  • 2Geomorphology & Glaciology, Department of Physical Geography, Stockholm University, Stockholm, Sweden (arjen.stroeven@natgeo.su.se)
  • 3Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden (alexander.lewerentz.sgu.se)
  • 4Umweltplanung Dr. Klimsa, Berlin, Germany (hippe.kristina@gmail.com)
  • 5Department of Earth Sciences, University of Gothenburg, Gothenburg, Sweden (jakob.heyman@gu.se)
  • 6Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, USA (nlifton@purdue.edu)
  • 7Department of Physics and Astronomy, Purdue University, West Lafayette, USA (mcaffee@purdue.edu)
  • 8Swedish Nuclear Fuel and Waste Management Company, Stockholm, Sweden (Jens-Ove.Naslund@skb.se)

The aim of this study is to test the Holocene relative sea-level (RSL) curve (or shoreline displacement curve) for east central Sweden using 14C produced in situ in quartz-bearing bedrock (in-situ 14C). The original RSL curve is instead based on radiocarbon dating of organic material from isolation basins. Having an accurate RSL curve is crucial from at least two aspects. In Sweden’s safety assessments for a planned spent nuclear fuel repository and for the existing repository for low- and intermediate level waste, the RSL curve is used to constrain the emergence above sea level in landscape development models. Also, the RSL is used to constrain model estimates of rates and depths of glacial and subaerial erosion from cosmogenic 10Be and 26Al produced in situ in quartz in bedrock surfaces.

Avoiding vein quartz and hydrothermally altered bedrock, five samples of granitoid bedrock were taken along an elevation transect extending southwards from Forsmark, the location of the planned spent nuclear fuel repository. Because all samples derive from bedrock outcrops positioned below the highest postglacial shoreline, they target the timing of progressive landscape emergence above sea level. To further assess the accuracy of in-situ 14C dating, we took an additional five samples from bedrock outcrops 100 km west of Forsmark, above the highest postglacial shoreline. The in-situ 14C concentrations in these samples should reflect local deglaciation ages.

The ten new in-situ 14C measurements provide robust age constraints that compare favorably with the original RSL curve derived from radiocarbon dating of organic material in isolation basins and with the regional deglaciation chronology. Inferences of limited rates and depths of bedrock erosion over the past 1 Myr, inferred from 10Be and 26Al inheritance and which are critically dependent on the RSL curve, therefore glean strong support from these new in-situ 14C measurements.

How to cite: Goodfellow, B. W., Stroeven, A. P., Lewerentz, A., Hippe, K., Heyman, J., Lifton, N. A., Caffee, M. W., and Näslund, J.-O.: Last ice sheet recession and landscape emergence above sea level in east central Sweden, evaluated using 14C produced in situ in quartz, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-6006, https://doi.org/10.5194/egusphere-egu23-6006, 2023.