geologia

Revista Brasileira de Geociências

29(3):379-392, setembro de 1999

AMERICA DO SUL: QUATRO FUSÕES, QUATRO FISSÕES E O
PROCESSO ACRESCIONÁRIO ANDINO
BENJAMIM BLEY DE BRITO NEVES
ABSTRACT SOUTH AMERICA: FOUR FUSIONS, FOUR FISSIONSAND THE ANDEAN ACCRECIONARY PROCESS The aim of this article is try to interpret -as a first approximation- the evolution of the South American continent from the point of view of the Supercontinents
Theory of the new Global Tectonics. It is preliminarly reiterated that the individualization of this lithospheric segment as a continent (geotectonic sense) is a fact younger than 100 Ma old, although we know about a crustal evolutionary history -as participant of other continental configurations as older as 3.5 Ga. Most of those previous continental configurations were larger in size than this now presented.
Four major processes of (super)continental agglutination are being identified and they will be described, three of them Precambrian in age in the upper part of the Proterozoic eras (Paleoproterozoic, Mesoproterozoic and Neoproterozoic). The last of these agglutination processes took place in Early Mesozoic times, after a long and complex Paleozoic history of accretions and interior collisions. Following each of these agglutinantion events there were wide processes of continental break up (taphrogenesis) and dispersion ( drift) of the descendant lithospheric segments, as result of the dissipation of heat from astenospheric realms.
The last process of dispersion, after the Triassic continental collage (Pangea supercontinent) is still under way, in terms of the present grouwth of the Atlantic Ocean. Só, it hás partially been coeval of the concurrent accretionary processes in the Andean Chain, which are somehow leading to a future continental agglutination (when of the disappearance of The Pacific and Caribbean oceanic segments). Such development of these two different and concurrent processes (at the western and eastern