Annually Laminated Lake Sediments and Their Palaeoclimatic Relevance

Summary

This review aims to give an overview on annually laminated (varved) lake sediments and provides a guideline of their use as palaeoclimatic proxy data archives. A brief survey of about one hundred years of varve research demonstrates the long history of dating and palaeoenvironmental reconstruction based on varved lake sediments. Considering methodologies, this review confines to some main principles and fundamental requirements for varve studies. The factors favouring varve deposition and preservation in lacustrine systems and consequences for the occurrence of long varved profiles are thoroughly discussed. The concept of varve micro-facies describes the main varve types and their relation to climatic regimes and environmental conditions. The palaeoclimatic relevance of varved lake sediments is reflected in a large variety of different proxy data. These are discussed under a more general aspect including the pathways of climatic signals into the sediment with special emphasis on the interpretation of varve thickness. Two case studies demonstrate the value of varve micro-facies analyses for obtaining a complex picture of changes in seasonality of past climates.