Sediment accumulation rates and geochronologies measured in the Saguenay Fjord using the Pb-210 dating method

Sediment accumulation rates were estimated from-the vertical distribution of excess Pb-210 measured in sediment cores collected at seven stations in the Saguenay Fjord, Quebec. These rates decrease with increasing water depth and distance from the mouth of the Saguenay River, ranging from 4.0 g cm^?2 yr^?1 (～- 7 cm yr^?1) near the head of the fjord to 0.07 g cm^?2 yr^?1 (～- 0.1 cm yr^?1) in the deep inner basin of the fjord. In one core from the head of the fjord, layered sediment structures, having different physical characteristics and composition, appear related to recent, pulsed inputs of older raised marine deposits displaced by a landslide in 1971. Synchronous depositional anomalies in several cores provide evidence of other large scale sediment redistribution processes in the fjord. Pb-210 geochronologies are generally in good agreement with time-stratigraphic horizons inferred both from Cs-137 activity profiles and from the analysis of pollen assemblages in one core.