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.




The South Atlantic


Book Description

The book presents results of recent projects in oceanography and marine geosciences (e.g. WOCE, JGOFS, PAGES, ODP) regarding present and past circulation in the South Atlantic. The objective of the book is to integrate results from both oceanographic and geological studies. As the connecting link between the Antarctic and the North Atlantic, the South Atlantic plays a crucial role with regard to the heat budget of the North Atlantic and to the biogeochemical budget of the global ocean. New results from studies of meridional water mass and heat transports are presented. The central theme of geological investigations is the reconstruction of current and productivity systems in the South Atlantic during the late Quaternary.




The South Atlantic in the Late Quaternary


Book Description

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.







Use of Proxies in Paleoceanography


Book Description

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.




Late Quaternary Stratigraphic Evolution of the Northern Gulf of Mexico Margin


Book Description

Late Quaternary stratigraphic evolution of the north Gulf of Mexico margin : a synthesis -- High-resolution stratigraphy of a sandy, ramp-type margin, Apalachicola, Florida -- Late Quaternary stratigraphic evolution of the Alabama-west Florida outher continental shelf -- late Quaternary geology of the northeastern Gulf of Mexico shelf : sedimentology, depositional history, and ancient analogs of a major shelf sand sheet of teh modern transgressive systems tract -- Sequence stratigraphy of a continental margin subjected to low-energy and low-sediment-supply environmental boundary conditions : late Pleistocene-Holocene deposition offshore Alabama -- Late Quaternary deposition and paleobathymetry at the shelf-slope transition, ancestral Mobile River delta complex, northeastern Gulf of Mexico -- Depositional architecture of the Lagniappe Delta : sediment characteristics, timing of depositional events, and temporal relations with adjacent shelf-edge deltas -- Foraminiferal biostratigraphy and paleoenvironments of the Pleistocene Lagniappe Delta and related section, northeastern Gulf of Mexico -- Late Quaternary stratigraphic evolution of the west Lousiana-east Texas continental shelf -- Late Quaternary Brazos and Colorado deltas, offshore Texas, their evolution and the factors that controlled their deposition -- Late Quaternary evolution of the wave-storm-dominated Central Texas Shelf -- Late Quaternary evolution of the Rio Grande Delta.




The South Atlantic in the Late Quaternary


Book Description

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.




Coccolithophores


Book Description

This introduction to one of the most common phytoplankton types provides broad coverage from molecular and cellular biology all the way to its impact on the global carbon cycle and climate. Individual chapters focus on coccolithophore biology, ecology, evolutionary phylogeny and impact on current and past global changes. The book addresses fundamental questions about the interaction between the biota and the environment at various temporal and spatial scales.