Annually Laminated Lake Sediments

The collection of papers presented in this book illustrates the recent progress made in varved sediment research and highlights the large variety of methodological approaches and research directions applied. The contributions cover monitoring of modern sediment fluxes using sediment traps; geochronological and sedimentological analyses of annually laminated lacustrine sediments or varves; and multiproxy investigations, including geochemical and biological proxies as well as spatiotemporal analyses based on multicore studies supported by satellite images and X-ray computed tomography (CT). The scientific issues discuss the influences of hydrological and climatological phenomena on short-term changes in sediment flux, the relationships between biogeochemical (limnological) processes in the water column and the formation of varves, the preservation of environmental signals in varved sediments, and possibilities of synchronizing varved records with other high-resolution environmental archives such as tree rings.

The collection of papers presented in this book illustrates the recent progress made in varved sediment research and highlights the large variety of methodological approaches and research directions applied. The contributions cover monitoring of modern sediment fluxes using sediment traps; geochronological and sedimentological analyses of annually laminated lacustrine sediments or varves; and multiproxy investigations, including geochemical and biological proxies as well as spatiotemporal analyses based on multicore studies supported by satellite images and X-ray computed tomography (CT). The scientific issues discuss the influences of hydrological and climatological phenomena on short-term changes in sediment flux, the relationships between biogeochemical (limnological) processes in the water column and the formation of varves, the preservation of environmental signals in varved sediments, and possibilities of synchronizing varved records with other high-resolution environmental archives such as tree rings.

This book reports on efforts by geoscientists and climate modellers (KIHZ) to assess natural climate variability during the Holocene. Part 1 is an overview of the climate system and its dynamics. Part 2 describes the efforts of the KIHZ members to reconstruct past climate by using proxy data derived from ice cores, lake sediments, tree rings and corals, statistical analyses and climate models.

Lakes in North America that are meromictic or that contain sediments with annual layers are assessed for their potential for reconstruction of ancient climates.

The magnitude and causes of decadal to century-scale changes in climate are major issues of global concern. The separation of anthropogenically driven change from natural 'baseline' variability within the atmosphere/ocean system is a prerequisite to identifying human impact on global climate. An understanding of past climate variability is therefore a key to predicting future climate change. The sedimentary record of the oceans, seas and lakes is produced by a series of depositional events that occur on seasonal timescales but can rarely be resolved due to mixing of the sediment by bottomdwelling organisms. Where they are preserved, laminated sediments act like tree rings to record these seasonal-scale processes, such as plankton blooms and floods, and provide a uniquely high-resolution record of environmental change. In addition, annually laminated or 'varved' sediment sequences act as geochronometers against which other timescales can be tested. Laminated sediments may therefore be used to develop records of interannual and decadal-scale variability which serve to test models of climate change. The authors cover a range of topics that include strategies for study and techniques of analysis. A series of case studies, dealing with a variety of lacustrine and marine records, illustrates the wide potential of laminated sediments as palaeoclimatic and palaeoceanographic indicators.

Origins of fallout radionuclides Sediment records of fallout radionuclides Simple dating models Vertical mixing Numerical techniques Radiometric techniques Discussion Summary Acknowledgements References 10. chronostratigraphic techniques in paleolimnology. Svante Björck & Barbara Wohlfarth 205 Introduction Methods and problems Radiocarbon-dating different fractions of the sediment as a chronostratigraphic tool Dating of long (old) stratigraphies High resolution dating and wiggle matching dating versus absolute dating techniques of lacustrine sediments Concluding remarks Summary Useful www addresses Acknowledgements References 11. Varve chronology techniques. Scott Lamoureux 247 Introduction Methods Summary and future directions Acknowledgements References 12. Luminescence dating. Olav B. Lian & D.J. Huntley 261 Introduction The mechanism responsible for luminescence Dating and estimation of the paleodose Thermoluminescence dating Optical dating Evaluating the environmental dose rate xi Sample collection and preparation What types of depositional environments are suitable for luminescence dating? What can lead to an inaccurate optical age? Summary Acknowledgements References 13. Electron spin resonance (ESR) dating in lacustrine environments. Bonnie A.B. Blackwell 283 Introduction Principles of ESR analysis Sample collection ESR analysis ESR microscopy and other new techniques Applications and datable materials in limnological settings Summary Acknowledgements References 14. Use of paleomagnetism in studies of lake sediments. John King & John Peck 371 Introduction Recording fidelity of geomagnetic behavior by sediments Field and laboratory methods Holocene SV records Magnetostratigraphic studies of Neogene lake sediments Excursions, short events and relative paleointensity Conclusions Summary References 15. Amino acid racemization (AAR) dating and analysis in lacustrine environments.

This is a guide to imaging techniques for sedimentologists, paleolimnologists, paleoceanographers and microscopists involved in paleoenvironmental reconstruction. Case studies illustrate the range of information obtainable from different sediments (marine, lacustrine, aeolian) and different types of samples (cores, embedded blocks, microscopic slides) using different regions of the electromagnetic spectrum (visible, UV, IR, X-ray). Includes comprehensive protocols, guidelines, and recommendations for the use of low cost image analysis techniques.