|Authors||S. Hippchen, B. Ghorbal, C. Moder and S. Clark|
|Title||Geology, Tectonics, and Intraplate Deformation in South America: Revisited Block Boundaries|
|Afilliation||, Kalkulo, Scientific Computing|
|Year of Publication||2012|
Plate reconstruction models are to a large part constrained by magnetic lineations on the seafloor. These lineations occur due to a reversal of the earth's magnetic field during the opening of a Mid-Ocean Ridge. In areas where part of the opening took place during the Cretaceous Superchron, a 30 Ma era when no magnetic reversal has been recorded, the reconstruction of plate motion becomes very difficult. Hence other parameters must be used in order to be able to constrain a model, and one of the most important aspects is the amount and distribution of intraplate deformation, which is used to divide the continent into different blocks to achieve the best possible pre-opening fit. The described difficulty constraining plate reconstruction models is a major issue in the modeling of the opening of the South Atlantic. Most existing plate models there seem to be almost exclusively based on geometrical constraints in order to achieve the best pre-opening fit possible, and geological and geophysical processes and mechanisms play a minor role in determining block boundaries. We compare the various existing plate reconstruction models, which show major differences in the intraplate deformation within the South American continent. We then use available data like gravity, crustal thickness, geology, major faults zones, basement age and changes of the dip angle of the downgoing slab of the Peru/Chile trench between the Nazca and the South American Plate to investigate current tectonics and strain distribution. Based on this detailed study of current tectonics, as well as a lithospheric block model for the evaluation of plate motion scenarios, we postulate an updated block geometry for South America and in a next step will study the implications of this updated model for the pre-opening fit of the South Atlantic.
Presented at AGU 2012 in San Francisco