Conjugate margins of the South Atlantic: Namibia-Pelotas

2012 ◽  
pp. 202-221 ◽  
Author(s):  
Joe Cartwright ◽  
Roger Swart ◽  
Branko Corner
Keyword(s):  
South Atlantic ◽  
The South ◽  
Conjugate Margins

Hotspot origin for asymmetrical conjugate volcanic margins of the austral South Atlantic Ocean as imaged on deeply penetrating seismic reflection lines

2019 ◽  
Vol 7 (4) ◽  
pp. SH71-SH97 ◽  
Author(s):  
Kyle Reuber ◽  
Paul Mann ◽  
Jim Pindell
Keyword(s):  
Oceanic Crust ◽  
Seismic Reflection ◽  
Seismic Refraction ◽  
South Atlantic ◽  
Plate Motion ◽  
Basin Evolution ◽  
Spreading Ridge ◽  
The South ◽  
Volcanic Material ◽  
Conjugate Margins

We have interpreted 27,550 km of deep-penetrating, 2D-seismic reflection profiles across the South Atlantic conjugate margins of Uruguay/Southern Brazil and Namibia. These reflection profiles reveal in unprecedented detail the lateral and cross-sectional, asymmetrical distribution of voluminous, postrift volcanic material erupted during the Barremian-Aptian (129–125 Ma) period of early seafloor spreading in the southernmost South Atlantic. Using this seismic grid, we mapped the 10–200 km wide, continental margin-parallel limits of seaward-dipping reflector (SDR) complexes — that are coincident with interpretations from previous workers using seismic refraction data from the South American and West African conjugate margins. Subaerially emplaced and tabular SDRs have rotated downward 20° in the direction of the mid-Atlantic spreading ridge and are up to 22 km thick near the limit of continental crust. The SDR package is wedge shaped and thins abruptly basinward toward the limit of oceanic crust where it transitions to normal, 6–8 km thick oceanic crust. We have developed a model for the conjugate rifted margins that combine diverging tectonic plates and northwesterly plate motion relative to a fixed mantle position of the mantle plume. Our model explains an approximately 30% higher volume of SDRs/igneous crust on the trailing Namibian margin than on the leading Brazilian margin during the syn- and postrift phases. Our model for volcanic margin asymmetry in the South Atlantic does not require a simple shear mechanism to produce the asymmetrical volcanic material distribution observed from our data and from previously published seismic refraction studies. Determining the basinward extent of the extended continental basement is crucial for understanding basin evolution and for hydrocarbon exploration. Although these conjugate margins have evolved asymmetrically, their proximity during the early postrift stage suggests a near-equivalent, early basin evolution and similar hydrocarbon potential. Understanding the tectonic and magnetic processes that produce these observed asymmetries is critical for understanding volcanic passive margin evolution.

POLITICAL AND STRATEGIC COORDINATION AND COOPERATION FOR DEVELOPMENT: THE CASES OF ZPCSA AND GGC

2016 ◽  
Vol 31 (2) ◽  
pp. 19-36
Author(s):  
Paulo Fagundes Visentini ◽  
Analúcia Danilevicz Pereira
Keyword(s):  
South Atlantic ◽  
Strategic Orientation ◽  
International Affairs ◽  
The South ◽  
Strategic Issues ◽  
Strategic Coordination ◽  
Regional Order ◽  
Energy Products ◽  
A Site ◽  
Political Economic

The creation of the Zone of Peace and Cooperation of the South Atlantic (ZPCSA) in 1986 and the Gulf of Guinea Commission (GGC) in 2001 was about changes in the distribution of world power. This article argues that though they emerged at different times, their strategic orientation converges in a number of areas related to the significant interests in the South Atlantic as an area of stability in the region to be marked by strong political, economic and military ties. They also converge on the ideal for development, security and greater projection of power and influence in international affairs. The South Atlantic being a route of passage and trade, as a means of access and flow of energy products, the region became a site for new calculations of regional strategic powers about world affairs. The article also argues that ZPCSA and GGC are therefore crucial for the regional order and the development of higher capacities for cooperation on strategic issues. The actual point of convergence extends to ensuring the sovereignty through dialogue between the states in the region that are involved.

Observed seasonal regimes of North-South Atlantic Ocean interbasin exchange

2019 ◽  
Author(s):  
Hamed D. Ibrahim
Keyword(s):  
North Atlantic ◽  
Climate Models ◽  
South Atlantic ◽  
Meridional Overturning Circulation ◽  
Volume Flux ◽  
The South ◽  
The North ◽  
Basin Scale ◽  
Interbasin Exchange ◽  
North And South

North and South Atlantic lateral volume exchange is a key component of the Atlantic Meridional Overturning Circulation (AMOC) embedded in Earth’s climate. Northward AMOC heat transport within this exchange mitigates the large heat loss to the atmosphere in the northern North Atlantic. Because of inadequate climate data, observational basin-scale studies of net interbasin exchange between the North and South Atlantic have been limited. Here ten independent climate datasets, five satellite-derived and five analyses, are synthesized to show that North and South Atlantic climatological net lateral volume exchange is partitioned into two seasonal regimes. From late-May to late-November, net lateral volume flux is from the North to the South Atlantic; whereas from late-November to late-May, net lateral volume flux is from the South to the North Atlantic. This climatological characterization offers a framework for assessing seasonal variations in these basins and provides a constraint for climate models that simulate AMOC dynamics.

MODELING THE SOUTH ATLANTIC OCEAN FROM MEDIUM TO HIGH RESOLUTION

2014 ◽  
Vol 31 (2) ◽  
Author(s):  
Mariela Gabioux ◽  
Vladimir Santos da Costa ◽  
Joao Marcos Azevedo Correia de Souza ◽  
Bruna Faria de Oliveira ◽  
Afonso De Moraes Paiva
Keyword(s):  
High Resolution ◽  
Atlantic Ocean ◽  
Large Scale ◽  
South Atlantic ◽  
Surface Relaxation ◽  
The South ◽  
Small Surface ◽  
Basic Model ◽  
Basic Set ◽  
Set Up

Results of the basic model configuration of the REMO project, a Brazilian approach towards operational oceanography, are discussed. This configuration consists basically of a high-resolution eddy-resolving, 1/12 degree model for the Metarea V, nested in a medium-resolution eddy-permitting, 1/4 degree model of the Atlantic Ocean. These simulations performed with HYCOM model, aim for: a) creating a basic set-up for implementation of assimilation techniques leading to ocean prediction; b) the development of hydrodynamics bases for environmental studies; c) providing boundary conditions for regional domains with increased resolution. The 1/4 degree simulation was able to simulate realistic equatorial and south Atlantic large scale circulation, both the wind-driven and the thermohaline components. The high resolution simulation was able to generate mesoscale and represent well the variability pattern within the Metarea V domain. The BC mean transport values were well represented in the southwestern region (between Vitória-Trinidade sea mount and 29S), in contrast to higher latitudes (higher than 30S) where it was slightly underestimated. Important issues for the simulation of the South Atlantic with high resolution are discussed, like the ideal place for boundaries, improvements in the bathymetric representation and the control of bias SST, by the introducing of a small surface relaxation. In order to make a preliminary assessment of the model behavior when submitted to data assimilation, the Cooper & Haines (1996) method was used to extrapolate SSH anomalies fields to deeper layers every 7 days, with encouraging results.

USING NEODYMIUM ISOTOPES TO DECIPHER COMPLEX CIRCULATION PATTERNS IN THE SOUTH ATLANTIC AT THE END OF THE CRETACEOUS

2020 ◽  
Author(s):  
Shannon J. Haynes ◽  
◽  
Kenneth G. MacLeod ◽  
Jean-Baptiste Ladant ◽  
Christopher J. Poulsen ◽  
...  
Keyword(s):  
South Atlantic ◽  
The South ◽  
Neodymium Isotopes ◽  
Circulation Patterns
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