Luminescence dating of loess-palaeosol sequences and coversands: methodological aspects and palaeoclimatic implications

Of the terrestrial archives, loess-palaeosol sequences provide a most compl ete record of climatic change. This may be compared with the Marine oxygen isotope stratigraphy, and may help in the reconstruction of past atmospheri c circulation patterns. Numerical chronometry of loess-palaeosol sequences has generally been based on correlation of variations in climatic proxies ( such as magnetic susceptibility and particle sizes) with Marine isotopic da ta. Such chronometric assignments involve implicit assumptions about the co nstancy of sedimentation rates and particle fluxes through time. This revie w presents a brief survey of the present status, methodology, outstanding p roblems and interpretational aspects of luminescence techniques, and discus ses the import of luminescence ages on global land-sea correlations. Statis tical analysis of the ages suggests episodicity of loess accumulation with extended periods of quiescence, Recent luminescence dating studies on close ly spaced samples also lead to a similar inference. Luminescence ages imply high variability in loess sedimentation rates. This conflicts with the ass umption, made in some current attempts to correlate loess records with mari ne records, of almost constant particle fluxes. A review of source-proximal coversand deposits of northwest Europe is also presented. Evidence of the onset of coversand deposition at 15 ka, with a peak in accretion during the Younger Dryas and subsequent minor reactivation episodes. is discussed. (C ) 2001 Elsevier Science B.V. All rights reserved.