Micromorphology of loess-paleosol sequences: a record of paleoenvironmental change

The record of paleoenvironmental change retained within thin sections from loess-paleosol sequences is discussed with reference to case studies from w estern Europe, China and northwestern USA. The paleoenvironmental significa nce of individual micromorphological features such as calcitic concentratio ns, clay coatings and cryogenic structures are first evaluated, and the val ue of recognising and interpreting microstratigraphic relationships of feat ures in terms of paleoenvironmental change is illustrated, Recent developme nts have seen a greater emphasis on using micromorphology within a pedosedi mentary approach, whereby both pedogenic and sedimentary processes are take n into account when interpreting loess-paleosol sequences. This has led not only to the acquisition of important information on conditions during phas es of enhanced loess accretion and periods of climatic transition, but also to an increased awareness of spatial changes in processes and environmenta l controls during particular time periods, Micromorphologically based recon structions have enabled the isolation of key stages of pedosedimentary deve lopment, although absolute dating of stages is often limited by lack of age controls. A novel approach aimed at addressing this limitation, afforded b y presence of datable tephra in microstratigraphic association with key mic romorphological features, is discussed. (C) 1999 Elsevier Science B.V. All rights reserved.