The Argentina Continental Margin

The evolution of the Argentina Continental Margin during the Quaternary and the stratigraphic and morphosedimentary configuration responded to climatic variability, oceanographic changes, glacioeustatic fluctuations and tectono-isostatic processes, which began to impact on the margin during previous geological periods. The final modeling of the margin was achieved in the late Miocene, when the interaction between the Antarctic and North Atlantic water-masses favored climatic and oceanographic changes with a profound effect on morphosedimentary features. In the Quaternary, the different regions of the margin distinctly responded to such changes. Whereas in the shelf the main modeling factors were the sea-level fluctuations of glacioeustatic origin and consequent marine-continental stratigraphic records, in the slope (particularly in the sector corresponding to the passive margin) the prevailing effect was the interaction between water-masses and the sea floor, giving origin to contouritic depositional systems accompanied of gravity processes responsible of turbiditic and mass-wasting deposits. Different relationships between contouritic and turbiditic facies respond to distinct combinations of oceanic circulation variability and the indirect effect on the sea floor of sea-level fluctuations. As a result of this complexity in the regional processes in the framework of the broad hemispheric oceanographic-climatic conditioning factors, the ACM can be considered as a complete archive for the Southern Ocean.

This book is a product of the joint JGOFS (Joint Global Ocean Flux Study)/LOICZ (Land–Ocean Interactions in the Coastal Zone) Continental Margins Task Team which was established to facilitate continental margins research in the two projects. It contains signi cant information on the physical, biogeochemical, and ecosystems of continental margins nationally and regionally and provides a very valuable synthesis of this information and the physical, biogeochemical and ecosystem processes which occur on continental margins. The publication of this book is timely as it provides a very strong foundation for the development of the joint IMBER (Integrated Marine Biogeochemistry and Ecosystems Research)/LOICZ Science Plan and Implemen- tion Strategy for biogeochemical and ecosystems research in the continental margins and the impacts of global change on these systems. This initiative will move forward integrated biogeochemical and ecosystems research in the continental margins. We thank all the contributors to this volume and especially Kon-Kee Liu who has dedicated a great deal of time to ensuring a high-quality book is published. IMBER Scienti c Steering Committee Julie Hall LOICZ Scienti c Steering Committee Jozef Pacyna v 1 Preface In general, interfaces between the Earth’s larger material reservoirs (i. e. , the land, atmosphere, ocean, and sediments) are important in the control of the biogeoche- cal dynamics and cycling of the major bio-essential elements, including carbon (C), nitrogen (N), phosphorus (P), sulfur (S), and silicon (Si), found in organic matter and the inorganic skeletons, shells, and tests of benthic and marine organisms.

The continental margins of the world constitute the most impressive and largest physiographic feature of the earth's surface, and one of fundamentally great geological significance. Continental margins have been the subject of increasing attention in recent years, an interest focused by a body of new data that has provided new insights into their character. This interest was further stimulated by the realization that, in addition to the abundant living resources, continental margins contain petroleum and mineral resources that are accessible with existing technology. This realization, along with their basic geological importance, has provoked further research into the nature of continental margins throughout the world. A summary of these findings, as related to both recent and ancient continental margins, is the subject of this book. At various times in the past we had been approached individually to prepare a basic reference to continental margins; we then proposed to do such a volume jointly. However, the stimulus for the present volume eventually arose from a Penrose Conference arranged through the Geological Society of America. This conference was attended by specialists of numerous disciplines and from throughout the world, many of whom insisted that such a volume would be both timely and useful. Consequently, we agreed to undertake the task of assembling this book, with the objectives of making it available as soon and as inexpensively as possible.

This textbook explains how mountains are formed and why there are old and young mountains. It provides a reconstruction of the Earths paleogeography and shows why the shapes of South America and Africa fit so well together. Furthermore, it explains why the Pacific is surrounded by a ring of volcanos and earthquake-prone areas while the edges of the Atlantic are relatively peaceful. This thoroughly revised textbook edition addresses all these questions and more through the presentation and explanation of the geodynamic processes upon which the theory of continental drift is based and which have led to the concept of plate tectonics. It is a source of information for students of geology, geophysics, geography, geosciences in general, general natural sciences, as well as professionals, and interested layman.

This reference on the geology and geophysics of continental margins contains a total of 15 papers developed from a session of the Fifth International Congress of the Brazilian Geophysical Society held in Sao Paulo, Brazil in 1997, as well as a number of other contributions. Subjects include the roots of the southeastern continental margin of Brazil, the mosaic of Terranes in central Europe, the evolution of the Angolan passive margin; geological and geophysical interpretation of the San Julian Basin offshore Argentina; and the tectonic evolution of the equatorial South Atlantic. Of likely interest to academic geoscientists working in basin analysis and those engaged in petroleum exploration. Member price, $52.50. Annotation copyrighted by Book News, Inc., Portland, OR.

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.