The South Atlantic in the Late Quaternary
The South Atlantic in the Late Quaternary

Author: Gerold Wefer

Publisher: Springer Science & Business Media

Published: 2004

Total Pages: 742

ISBN-13: 9783540210283

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The South Atlantic plays a significant role as a link between the Antarctic Ocean and the North Atlantic, both in terms of the heat budget of the North Atlantic and the circulation of the entire ocean. The heat and mass exchanges between the Antarctic Ocean and the South Atlantic during the Late Quaternary have been investigated over the past ten years, including their impact on world climate. This has required the study of present-day early diagenetic processes in the water column and sediments, as well as sediment properties that have a close relationship to environmental parameters ("proxies"), which can be used to decipher past conditions (temperature, salinity, productivity, etc.). The interdisciplinary research project "The South Atlantic in the Late Quaternary - Reconstruction of material budgets and current systems" was a long-term scientific program at Bremen University. This program benefited from the sample material gained on several expeditions with the research vessels Meteor and Polarstern. This book presents the summarized results of the various topics of study in 30 articles arranged in seven sections. TOC:Particle Flux in the South Atlantic.- Documentation of the Marine Environment in Microfossil Assemblages and Stable Isotopes.- Physical Sedimentary Records of Palaeoenvironmental and Depositional Conditions.- Source and Transport Signatures of the Terrigenous Sediment Fraction.-Early Diagenetic Processes and Preservation of Primary Signals.-History of Upper Ocean Circulation.- History of Bottom and DeepWater Circulation.-

The South Atlantic in the Late Quaternary
The South Atlantic in the Late Quaternary

Author: Gerold Wefer

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 742

ISBN-13: 3642189172

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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.

Use of Proxies in Paleoceanography
Use of Proxies in Paleoceanography

Author: Gerhard Fischer

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 768

ISBN-13: 3642586465

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Paleoceanographic proxies provide infonnation for reconstructions of the past, including climate changes, global and regional oceanography, and the cycles of biochemical components in the ocean. These prox ies are measurable descriptors for desired but unobservable environmental variables such as tempera ture, salinity, primary productivity, nutrient content, or surface-water carbon dioxide concentrations. The proxies are employed in a manner analogous to oceanographic methods. The water masses are first characterized according to their specific physical and chemical properties, and then related to particular assemblages of certain organisms or to particular element or isotope distributions. We have a long-standing series of proven proxies available. Marine microfossil assemblages, for instance, are employed to reconstruct surface-water temperatures. The calcareous shells of planktonic and benthic microorgan isms contain a wealth of paleoceanographic information in their isotopic and elemental compositions. Stable oxygen isotope measurements are used to detennine ice volume, and MglCa ratios are related to water temperatures, to cite a few examples. Organic material may also provide valuable infonnation, e. g. , about past productivity conditions. Studying the stable carbon isotope composition of bulk organic matter or individual marine organic components may provide a measure of past surface-water CO 2 conditions within the bounds of certain assumptions. Within the scope of paleoceanographic investigations, the existing proxies are continuously evolving and improving, while new proxies are being studied and developed. The methodology is improved by analysis of samples from the water column and surface sediments, and through laboratory experiments.

The Northern North Atlantic
The Northern North Atlantic

Author: Priska Schäfer

Publisher: Springer Science & Business Media

Published: 2001-04-02

Total Pages: 520

ISBN-13: 9783540672319

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The northern North Atlantic is one of the regions most sensitive to past and present global changes. This book integrates the results of an interdisciplinary project studying the properties of the Greenland-Iceland-Norwegian Seas and the processes of pelagic and benthic particle formation, particle transport, and deposition in the deep-sea sediments. Ice-related and biogeochemical processes have been investigated to decipher the spatial and temporal variability of the production and fate of organic carbon in this region. Isotopic stratigraphy, microfossil assemblages and paleotemperatures are combined to reconstruct paleoceanographic conditions and to model past climatic changes in the Late Quaternary. The Greenland-Iceland-Norwegian Seas can now be considered one of the best studied subbasins of the world`s oceans.