SELECTIVE CONCENTRATION AND ENUMERATION OF TEPHRA SHARDS FROM LAKE SEDIMENT CORES

This paper describes a technique for the enumeration of tephra shards from lake sediment cores whereby approximately 85% of unwanted sedimen t fractions (organic matter, biogenic silica, carbonates) are removed by selective stepwise chemical attack The order of 100 samples can be prepared simultaneously in a modest-sized water-bath and the recovery rate of the technique is greater than 90%. The procedure is applicable to all lake sediment types.