Quaternary Climates, Environments and Magnetism


Book Description

The Quaternary has been a period of major climatic and environmental oscillations, and our knowledge of these past variations is important for our understanding of the possible impact of human activity on the present-day environment. First published in 1999, Quaternary Climates, Environments and Magnetism presents an account of the rich variety of uses of magnetic measurements in the environmental geosciences. Ten chapters by leading world authorities describe the highlights of environmental magnetic work during the last decade and identify directions for future research. Emphasis is placed on a multidisciplinary approach to achieve a more thorough understanding of the environmental processes involved. This volume will be of interest to research scientists from a wide range of disciplines working on Quaternary environments, including earth and environmental sciences, physical geology, geography and palaeoclimatology. It will also be valuable as a supplementary text for graduates and advanced undergraduates.




Geomagnetic Field Variations in the Past


Book Description

In the last decades, palaeomagnetic research has provided important information about the past variation of the Earth’s magnetic field (EMF) from its origin to the present day. However, questions regarding the origin and evolution of the EMF as well as the frequency and spatial distribution of its variations still remain open to debate. This Special Publication provides new insights into the study of the temporal and spatial evolution of the EMF presenting new data from palaeomagnetic and rock magnetic studies of archaeological materials, sediments and lavas. The papers presented cover a wide range of topics related to archaeology, stratigraphy and climate, including new data from several parts of the world, such as Europe, Africa, Australia, New Zealand, India and the Baltic Sea. This Special Publication aims to present an overview of the most recent secular variation studies and their use to disclose fundamental properties of the EMF evolution.




Geomagnetic Field Variations


Book Description

Earth’s magnetic field is currently changing dramatically. Is the observed decrease of the dipole moment indicating a future polarity transition? What would be the effects of such a drastic change on system Earth? Can any positive or negative effects on our biosphere or even humans be expected? This book gives a first overview about the geomagnetic field in general and serves as an introduction into geomagnetism. As the topic of the book covers a wide range of scientific disciplines, the first chapter summarises basic principles of geomagnetism and related fields including a historic overview, instruments and measurements, paleomagnetic fields, basics of dynamo theory, etc. The contributed chapters review major results of international activities aiming at understanding the causes and effects of geomagnetic field variations in view of the questions above.







The Evolving Geomagnetic Field


Book Description

Earth’s magnetic field has protected our planet for billions of years and provides key insights into the internal workings of our home planet. The geomagnetic field varies in distinctive fashions across a broad spectrum of timescales from milliseconds to millions of years. To understand these variations, Earth scientists utilize a diverse arsenal of tools from hi-tech satellites, such as the Swarm array, to archeological pottery and geological materials, through to advanced numerical simulations that harness the power of supercomputers. Armed with these tools we tackle problems related to the ancient magnetic field, how the geodynamo works and what this means for modern life. Despite being studied for more than 400 years, there are many unanswered questions about the geomagnetic field. This Research Topic on “The Evolving Geomagnetic Field” brings together these varied approaches to present our latest understanding of the workings of the geodynamo and the geomagnetic field across all timescales.




The South Atlantic in the Late Quaternary


Book Description

The South Atlantic plays a critical role in the couplingofoceanic processes between the Antarctic and the lower latitudes. The Antarctic Ocean, along with the adjacent southern seas, is of substantial importance for global climate and for the distributionofwater masses because itprovides large regions ofthe world ocean with intermediate and bottom waters. In contrast to the North Atlantic, the Southern Ocean acts more as an "information distributor", as opposed to an amplifier. Just as the North Atlantic is influencedby the South Atlantic through the contributionofwarm surface water,the incomingsupply ofNADW - in the area of the Southern Ocean as Circumantarctic Deep Water - influences the oceanography ofthe Antarctic. The competing influences from the northern and southern oceans on the current and mass budget systems can be best studied in the South Atlantic. Not only do changes in the current systems in the eastern Atlantic high-production regions affect the energy budget, they also influence the nutrient inventories, and therefore impact the entire productivity ofthe ocean. In addition, the broad region of the polar front is a critical area with respect to productivity-related circulation since it is the source of Antarctic Intermediate Water. Although theAntarctic Intermediate Watertoday liesdeeper than the water that rises in the upwelling regions, it is the long-term source ofnutrients that are ultimately responsible for the supply oforganic matter to the sea floor and to sediments.




Quaternary Dating Methods


Book Description

Quaternary Dating Methods




Tracking Environmental Change Using Lake Sediments


Book Description

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.




Proxies in Late Cenozoic Paleoceanography


Book Description

The present volume is the first in a series of two books dedicated to the paleoceanography of the Late Cenozoic ocean. The need for an updated synthesis on paleoceanographic science is urgent, owing to the huge and very diversified progress made in this domain during the last decade. In addition, no comprehensive monography still exists in this domain. This is quite incomprehensible in view of the contribution of paleoceanographic research to our present understanding of the dynamics of the climate-ocean system. The focus on the Late Cenozoic ocean responds to two constraints. Firstly, most quantitative methods, notably those based on micropaleontological approaches, cannot be used back in time beyond a few million years at most. Secondly, the last few million years, with their strong climate oscillations, show specific high frequency changes of the ocean with a relatively reduced influcence of tectonics. The first volume addresses quantitative methodologies to reconstruct the dynamics of the ocean andthe second, major aspects of the ocean system (thermohaline circulation, carbon cycle, productivity, sea level etc.) and will also present regional synthesis about the paleoceanography of major the oceanic basins. In both cases, the focus is the "open ocean leaving aside nearshore processes that depend too much onlocal conditions. In this first volume, we have gathered up-to-date methodologies for the measurement and quantitative interpretation of tracers and proxies in deep sea sediments that allow reconstruction of a few key past-properties of the ocean( temperature, salinity, sea-ice cover, seasonal gradients, pH, ventilation, oceanic currents, thermohaline circulation, and paleoproductivity). Chapters encompass physical methods (conventional grain-size studies, tomodensitometry, magnetic and mineralogical properties), most current biological proxies (planktic and benthic foraminifers, deep sea corals, diatoms, coccoliths, dinocysts and biomarkers) and key geochemical tracers (trace elements, stable isotopes, radiogenic isotopes, and U-series). Contributors to the book and members of the review panel are among the best scientists in their specialty. They represent major European and North American laboratories and thus provide a priori guarantees to the quality and updat of the entire book. Scientists and graduate students in paleoclimatology, paleoceanography, climate modeling, and undergraduate and graduate students in marine geology represent the target audience. This volume should be of interest for scientists involved in several international programs, such as those linked to the IPCC (IODP – Integrated Ocean Drilling Program; PAGES – Past Global Changes; IMAGES – Marine Global Changes; PMIP: Paleoclimate Intercomparison Project; several IGCP projects etc.), That is, all programs that require access to time series illustrating changes in the climate-ocean system. - Presents updated techniques and methods in paleoceanography - Reviews the state-of-the-art interpretation of proxies used for quantitative reconstruction of the climate-ocean system - Acts as a supplement for undergraduate and graduate courses in paleoceanography and marine geology