MORPHO-STRUCTURAL CHARACTERIZATION AND TECTONIC EVOLUTION OF RIO GRANDE RISE (RGR)
Rio Grande Rise, South Atlantic, Crustal Model, Mega-Pockmarks, Mantle Plume, Structure Ridge, Crustal Contamination
The Rio Grande Rise (RGR) is an oceanic plateau in the SW Atlantic encompassing the older part of the Tristan-Gough (TG) hotspot track and paired with the Walvis Ridge (WR) located on the eastern side of the Mid-Atlantic Ridge (MAR).
This work show new evidences emerged with the current morpho-structural study conducted at the RGR. The combination of gravimetric, magnetometric, seismic, bathymetric and geochemical data, it was possible to obtain a new vison about the morphostructural complex of the Rio Grande Rise, giving rise to the suggestion of the evolutionary kinematic model from the opening of Gondwana to the days current.
Therefore, there are strong indications that the ERG may be a part of the continental crust current Pelotas basin bounded between the Rio Grande and Chuí Fracture Zones, which was captured by the South American plate when there was the continental separation aproximately 120 Ma ago.
Based on the interpretation of geophysical data, occurrences of gas escape zones (mega-pockmarks), as well bed forms and rocky outcrops, were identified in detail. In depth were identified areas of normal faults, sedimentary noise by acoustic turbidity, basement and depth of Moho, also identified features that indicate the possible exhumation of the mantle in block 01 of the delta area and old dorsal axes throughout the area.
The results have important implications for understanding of continental rifting, oceanic basins formations and the role of microcontinents in the formation of hot spot trails