Cosmogenic Exposure Dating (36Cl) of Landforms on Jan Mayen, North Atlantic, and the Effects of Bedrock Formation Age Assumptions on 36Cl Ages ...

• Main Authors: Anjar, Johanna, Akçar, Naki, Larsen, Eiliv A., Lysa, Astrid, Marrero, Shasta, Mozafari, Nasim, Vockenhuber, Christof
• Format: Article in Journal/Newspaper
• Language: English
• Published: ETH Zurich 2021
• Subjects: cosmogenic surface exposure dating; 36Cl; background production; Iceland; Jan Mayen; North Atlantic
• Online Access: https://dx.doi.org/10.3929/ethz-b-000508229; http://hdl.handle.net/20.500.11850/508229

Jan Mayen is a small volcanic island situated 550 km north of Iceland. Glacial sediments and landforms are relatively common on the island but, so far, only a few of them have been dated. In this study, we present and discuss 89 36Cl dates of primarily glacial and volcanic events on Jan Mayen. Calculations of sample exposure ages were complicated by young exposure ages, young rock formation age, and high native Cl contents, leading to updates in CRONUScalc to enable accurate exposure age calculations. The samples provide good evidence against an equilibrium assumption when subtracting background production (e.g., 36Cl produced by neutron capture from fission of U or Th) for samples on young bedrock, with younger exposure ages most significantly affected. Exposure ages were calculated with a range of assumptions of bedrock formation ages appropriate for Jan Mayen, including the assumption that the rock formation age equaled the exposure age (i.e., the youngest age it could possibly have), and we found that ... : Geosciences, 11 (9) ...