Paleoenviromental Reconstruction from the Sediment Record of the Varved Proglacial Linnévatnet, Svalbard, Norwegian High Arctic

• Main Author: Williams, Gwenyth
• Format: Text
• Language: unknown
• Published: SCARAB 2017
• Subjects: Arctic; Linnéelva; Linnévatnet; Svalbard; glacier; Magnetic susceptibility; Spitsbergen
• Online Access: https://scarab.bates.edu/geology_theses/35; https://scarab.bates.edu/cgi/viewcontent.cgi?article=1037&context=geology_theses

Arctic environments are highly sensitive to local climate variability, which can be reconstructed using a number of proxies. Linnévatnet is a proglacial deep lake located on Western Spitsbergen, Svalbard in the Norwegian High Arctic. The distinctly seasonal arctic climate and deep-lake setting allow for the deposition of annually laminated sediments. Sediments are sourced from glacier-fed Linnéelva at the southern end of the lake, a currently-stagnant cirque glacier to the West, and overland flow from alluvial fans that occurs mainly during melt and rain events. Two sediment cores, each measuring approximately 26 centimeters in length, were collected from the East Basin of Linnévatnet at coring sites C (more proximal) and D (more distal) in July, 2016. The cores were subsampled for grain size, bulk density, and for the production of thin sections. Magnetic susceptibility and ITRAX X-ray fluorescence were measured on the archive halves of the cores. Lead 210 and cesium 137 geochronology and varve measurements from previous studies were used to corroborate the varve chronology. Laminations were correlated between the two cores. Some laminations include complex structures which can be interpreted as non-cyclical sedimentation events. Core C extends back to approximately 150 years before present while the record in Core D extends to approximately 250 years before present. An increase in varve thickness during the past century correlates to the warming following the cool Little Ice Age. Calcium peaks can be seen in several cores taken from Linnévatnet at proximal and distal locations. Detrital calcium is sourced from the limestones and dolomites present in the bedrock geology of the eastern side of the valley. Other relevant element geochemistry was used to identify sediment provenance and possible events leading to deposition.