Sedimentological descriptions and results of analytical tests of sediment cores from fjords and lakes in northwest Western Norway

Abstract

This cooperative project, involving NGU. Norsk Hydro ASA, the University ofBergen and Sogn og Fjordane College, aims at documenting past slide\/masasmovement events recorded in Holocene fjord and lake sediments in western Norwaybetween Sognefjorden and Kristiansund. The assessment og triggering mechanismsof past mass movements is of critical importance for evaluating future risks oncoastal infrastructure and offshore installations.In this report (Phase c) we present the results of laboratory tests and visualdescriptions performed on 43 fjord cores and 26 lake cores that have beencollected in the frame of the current project. Most of the core have beenprofiled using the X-ray inspection system (XRI) and the multi sensor corelogger (MSCL). 55 cores were opend and sedimentologically described.Determinations of geotechnical parameters and sediment physical properties werecarried out on 27 and 26 fjord cores, respectively. Grain-size distibution hasbeen analysed in 35 samples from 3 fjord cores. Radiocarbon dating offoraminifers and shells in fjord cores and bulk gyttja and shells in lake coreswas carried out using both accelerator mass spectrometry (AMS) and conventionalradioactive counting methods. The dating samples were typically collectedbeneath or close to relatively coarse grained sediment intervals that canpossibly be linked to mass movement events. 51 samples from 25 cores have beendated and calendar year ages before present (BP) are reported in the next andon figures.