Deposition of fine-grained sediments in a proximal glacimarine environment near Berghem, southwestern Sweden

Abstract

The depositional environment of fine-grained sediments distal to the Berghem end-moraine zone at Berghem is interpreted from a detailed investigation of a 5 m long core sequence. Palacontological data (foraminifers, moluses, diatoms and pollen) indicate a high accumulation rate in a glacimarine environment. From sedimentological characteristics of the sediments it is concluded that deposition from meltwater overflow caused high accumulation rates close to the ice-front. In the bottom of the sequence, deposition of silty clays is interrupted by deposition of coarser layers from sediment gravity flows (including, e.g., turbidity currents and meltwater underflows), while in the upper part coarser layers are absent due to glacier retreat. Radiocarbon dating gave ages of c. 13,000 B.P., which is 600 years older than expected. Either a correction of the deglaciation chronology is necessary, or the unexpectedly high age can be explained by old carbonates transported into the glacimarine environment.

Key Words:

• Berghem
• southwestern Sweden
• fine-grained sediments
• glacimarine environment
• grain-size parameters
• radiocarbon dating