Characteristics of floodplain deposits within a braided sandur system in upper erdalen (nordfjord, western norway)

摘要

This study aims to characterize the morphology and contemporary floodplain deposit dynamics within a braided sandur system in upper Erdalen, a steep U-shaped valley in western Norway. The braided sandur system is fed by two tributary valleys connected to the Jostedalsbreen Ice Field. Based on field observations, two different sub-systems can be identified within the braided sandur system: fine-grained to sandy flood sediments down-valley, and coarser, gravelly deposits in the upper part. A combination of different methods is applied for studying sediment dynamic processes within the braided sandur system (sedimentological and stratigraphic analyses, ~(14)C dating, dendrochronology and lichenometry). The coarser deposits are interpreted as originating from the Little Ice Age advance in Erdalen. Preliminary results indicate that the floodplain sediments were deposited after the Little Ice Age advance. Different sedimentary facies types are present and different phases of flooding can be identified. Within the entire braided sandur system, multiple sub-systems characterized by different levels of process intensities exist.