A stratigraphical-sedimentological study of the last interglacial period in the central Nordic seas on the basis of XRF core scanning

• Main Authors: Kolling, Henriette, Bauch, Henning A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Deutsche Gesellschaft für Polarforschung; Alfred-Wegener-Institu für Polar- und Meeresforschung 2017
• Subjects: Nordic Seas; Polarforschung
• Online Access: https://oceanrep.geomar.de/id/eprint/40985/; https://oceanrep.geomar.de/id/eprint/40985/1/AWI_Polar_FB87-1_015-022.pdf; https://doi.org/10.2312/polarforschung.87.1.15

The recognition of specific geological time intervals is one of the major issues when establishing the stratigraphies of marine sediment cores. The automatic XRF core scanning method provides a fast and non-destructive method to precisely identify a given time interval and its changeable sedimentation histories. To test the applicability of XRF core scanning to recognize such periods, we studied in detail sedimentation processes across the last interglacial climate cycle (MIS 5e) on unsampled sediment core section from the central Nordic Seas – an area of high interest for paleoceanographic reconstructions. To further ground truth the XRF scanning results the core was sampled and the contents of iceberg-rafted debris (IRD) and shards of tephra were quantified. On that basis we identified Ti/Ca ratios as a potential indicator for IRD depositional peaks, and Ca as indicator of high biogenic carbonate production. Two well-known tephras from MIS 5e, Midt-RHY and 5e-low/Bas-IV, could be identified based on specific elemental content, such as Si, Ti, Zr, and Rb. By cross-core correlations using Ca-content and IRD-counts, the iceberg-free interval with enhanced deposition of biogenic carbonate lasted for about 9 ky, with a return of significant iceberg presence around 115 ka, notifying the onset of the last glacial inception. According to the age model applied we could further define the age of the 5e-Midt-RHY tephra at ~121.5 ka and of the 5e-low/Bas-IV at ~125.5 ka.