The Argentina Continental Margin - Violante, Roberto A.

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Résumé :
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.

Biographie:
Dr. Roberto Antonio Violante has a degree in Geology from the Faculty of Natural Sciences, University of La Plata, Argentina. Basic degree obtained in 1975. PhD obtained in 1988. Specialized in Coastal Geology at Florida State University, Tallahassee, Florida, USA. He has been working at the Argentina Hydrographic Survey since 1975, in the division of Marine Geology and Geophysics (Department of Oceanography). He is presently a Principal Researcher, Projects Director and Chief of the Marine Geology Section. His main research interests are: marine, coastal and lacustrine geology...

Sommaire:

The Argentina Continental Margin (ACM).- Location in the context of the Southern Hemisphere, the southern tip of South America and Antarctica.- The ACM as an archive for paleoclimatic and paleoceanographic changes.- Local and regional processes: climate, oceanography, sea-level fluctuations, isostasy, tectonism, sediment supply, sedimentary processes.- Oceanographic Context: interaction between Antarctic and Equator water-masses.- Environments: continental shelf, slope, rise, ocean basin.- Sedimentary processes in each of them: along-shore and across-shore processes.- Effects of the sea-level fluctuations on the shelf.- Effects of the water-masses circulation on the slope and rise.- Turbiditic and contouritic processes.- Morphosedimentary features in each environment.- The significance of the ACM as a potential archive for understanding local and regional processes.