Strontium isotope systematics and the age of melting ice in the Oppstryn drainage basin, Western Norway

Abstract

A preliminary assessment of the distribution of ⁸⁷Sr/⁸⁶Sr ratio in suspended sediments in stream waters of the Oppstryn drainage basin, located in the north-western part of Jostedalsbreen (Jostedal Glacier, Western Norway), was carried out during late summer 2006. The measured ⁸⁷Sr/⁸⁶Sr ratios vary between 0.71256 and 0.71567 compared to 0.7092 in average seawater and c.0.7098 in rainwater. The highest value was measured in a sample of suspended sediment particles from the glacial lake located below Erdalsbreen, and the lowest value was measured in suspended sediment particles in the river draining Vetledalsbreen. An intermediate value was measured in the sandur area below the confluence of Stordalselva and Vetledalselva. The measured difference in ⁸⁷Sr/⁸⁶Sr ratio between the uppermost and lowermost locations of the investigated part of the drainage basin was 1.75 x 10⁻³. This is significant and sufficient for application in future estimates of weathering rates. The age of water in the glacial lake at the outlet of Erdalsbreen was determined as being in the range 1110±30 to 1430±45 y BP.

Keywords:

• carbon
• Erdalsbreen
• Jostedalsbreen
• meltwater
• Norway
• Oppstryn
• strontium isotopes
• weathering

Acknowledgements

The first-named author is grateful to Steinar Gulliksen, Head of the Laboratory of Radiological Dating at the Norwegian University of Science and Technology (NTNU), for both his and his colleagues’ efforts in obtaining the age of the water in the glacial lake by ¹⁴C chronology.