Depositional Settings of an Arctic Coast: A Shallow Seismic Investigation

• Main Authors: Radosavljevic, Boris, Lantuit, Hugues, Fritz, Michael, Overduin, Paul, Krautblatter, Michael
• Format: Conference Object
• Language: unknown
• Published: 2013
• Subjects: Arctic; Climate change; Herschel; Herschel Island; Ice; Mackenzie river; permafrost; Yukon
• Online Access: https://epic.awi.de/id/eprint/34594/; https://epic.awi.de/id/eprint/34594/1/2013_Radosavljevic_ArcticNet.pdf; https://hdl.handle.net/10013/epic.42804; https://hdl.handle.net/10013/epic.42804.d001

A shallow seismic investigation of the possibility of sediment and carbon deposition was conducted in nearshore areas of Herschel Island, Yukon Territory, Canada. Permafrost coasts are known to erode rapidly, despite being protected from erosion by ice from October to June. Even though protected from wave attack for nine months of the year, arctic coasts made of unconsolidated sediments erode very rapidly due to the combined effects of mechanical and thermal erosion processes. In particular, coasts characterized by ice-rich permafrost, like the western Canadian Arctic are especially vulnerable to climate change. Recent estimates indicate carbon stored in permafrost soils exceeds the atmospheric carbon pool by factor two. With the potential for positive feedback to ongoing climate change, processes leading to the release and sequestration of the carbon have received much scientific attention. These processes include coastal erosion and burial in the marine realm. Carbon input from the Mackenzie River and deposition on the Beaufort continental shelf has been quantifi ed by previous studies; however depositional settings in the nearshore zone have not been thoroughly investigated. Th is is due to logistical diffi culties, but also because in many cases, erosional processes dominate on the arctic shoreface. Shallow seismic profiles were obtained along transects in three areas of the roughly rectangular island. Areas of deposition were identified in the SE region of the island. Th is area is protected from prevailing winds from the NE by the island itself. To a degree, the island also shields this area from ice movement on the open sea and associated ice-gouging. In comparison with transects around the island, it was found that exposure, not depth, controls the depositional regime. Exposure to ice processes is indicated by highly disturbed stratigraphy, interpreted as ice-keel turbate.