F. Høgaas, L. Olsen, L. Gislefoss, O. Longva, Anders Romundset, H. Sveian
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引用次数: 0
Abstract
This paper presents results from glacial geomorphology mapping in and adjacent to Velfjorden and Ursfjorden in the southern Nordland region of Norway. Submarine and terrestrial landforms were studied and mapped using high-resolution multibeam bathymetric and airborne LiDAR data, in addition to reconnaissance in the field. The work unites ice-marginal deposits related to the established Tautra and Tjøtta glacial events which took place during the Younger Dryas (YD) chronozone. In Ursfjorden, an outlet glacier deposited a c. 100 m-high terminal moraine, whereas moraine ridges and a large sedimentary wedge were deposited in the inner part of Velfjorden. Highly elongated subglacial bedforms located inside the ice-marginal landforms reveal that the fjords were occupied by fast-flowing ice streams during YD. Eighteen new radiocarbon dates from the region, along with twelve recalibrated dates from previous studies, provide time-constraints for ice-sheet configuration and dynamics during deglaciation. Radiocarbon dates suggest that the outer coastal islands became ice-free prior to 14 cal ka BP. Glacially overridden shell-rich units dated to the Allerød Interstadial indicate that the YD ice sheet readvanced at least 5 km before depositing the terminal moraine in Ursfjorden. The ages of shells found near the distinct, regionally correlative, YD raised shoreline indicate that the glacial readvance culminated around early to mid-YD.
期刊介绍:
The Norwegian Journal of Geology publishes high-quality, fully peer-review papers from all geoscientific disciplines. Papers are commonly based on regional studies and should emphasise the development of understanding of fundamental geological processes. More specialised papers can also be submitted, but should be written in a way that is easily understood by nonspecialists, and illustrate the progress being made within that specific topic in geosciences. We also encourage initiatives for thematic issues within the scope of the Journal.