PALAEOCLIMATIC IMPLICATIONS OF MAGNETIC PROPERTIES AND GEOCHEMISTRY OF HOLOCENE SEDIMENTS FROM BOSTEN LAKE, XINJIANG, CHINA

Bosten Lake is a large (1019 km2 area), shallow (maximum depth 15.7 m), currently eutrophic lake in the Yanqui Basin, southern Xinjiang province, China. We retrieved a ~9 m-long piston core from a site in 5.5 m water depth in the northwestern corner of the lake in summer 2000. The lithology consists of carbonate (up to ~80%) with varying amounts of fluvially-derived siliciclastic material. We measured rock magnetic, geochemical and textural characteristics on the core as part of a multi-disciplinary project to reconstruct the Holocene climatic history of the site. The record shows coherent variations in magnetic, geochemical and textural properties, which we take to reflect fluctuations in fluvial sediment supply and in lake level. The magnetic properties are significantly influenced by the presence of the ferrimagnetic iron sulphide greigite, the occurrence of which is associated with phases of lowered lake level. An initial low resolution AMS 14C chronology enables us to date the episodes of inferred lowered lake level, and to make tentative correlations with published Holocene climate records from north China