The magnetic record of the Late Glacial-Holocene transition in sediments from Grandfather Lake (Southwest Alaska)

Abstract

Preliminary rock magnetic measurements on a 8.5 m long sediment core from Grandfather Lake, southwest Alaska, indi- cate that the remanence in these sediments is carried by large multi-domain magnetite grains. This suggests a detrital magnetic signal. An abrupt change in magnetic properties at 5.95 m depth (ca. 9500 14C yr.) probably reflects the beginning of the temperate Holocene. The magnetic and pollen records show different patterns below this transition. The latter suggests the occurrence of a first slight warming at the end of the Late Glacial period, followed by the Younger Dryas cooling event and the actual beginning of the Holocene. Neither the first warming event nor the Younger Dryas are recorded in the magnetic signal. One of the explana- tions for this discrepancy is that the impact of these climate events, if any, may have been limited in this region.