Late Weichselian-Holocene evolution of the high-latitude Andoya submarine Canyon, North-Norwegian continental margin

摘要

Canyons are rare on most glaciated continental margins and little is generally known on their evolution. Here we have analysed high-resolution geophysical data and sediment cores from one of these canyons, the Andoya Canyon located on the north-Norwegian continental margin, in order to study the sedimentary processes and paleoenvironment of this system from the Last Glacial Maximum until the present. During the last glacial maximum and the early deglaciation (>similar to 15 ka cal BP) up to 570 turbidites per thousand years were deposited on the northern levee of the lower canyon. The turbidity currents were relatively large and deposited sandy turbidites on the levee, up to 90 m above the floor. We ascribe this high frequency of turbidity currents to an episodic but relatively constant supply of sediments due to the presence of the Andfjorden paleo-ice stream at the shelf break, i.e. very close to the canyon head. The frequency and volume of turbidity currents decreased during the deglaciation (similar to 15-11.7 ka cal BP) as the sediment supply from the Andfjorden paleo-ice stream ceased. However, the increase in strength of northward and alongslope flowing ocean bottom currents caused winnowing on the continental shelf south of the canyon and led to the deposition of sediments in the southern canyon wall area. These sediments occasionally failed and led to the deposition of turbidites in the lower Andoya Canyon. The Holocene record is dominated by hemipelagic sediments generated by the increased strength of the northward flowing bottom currents causing more profound winnowing of the shelf sediments during this period. A few sandy turbidity currents were also triggered during this period. Thus within the high-latitude Andoya Canyon, turbidity currents were the most important process eroding and transporting sediments into the deep sea. (C) 2015 Elsevier BY. All rights reserved.