Episodic Remagnetizations related to tectonic events and their consequences for the South America Polar Wander Path
Libro: Remagnetization and Chemical Alteration of Sedimentary Rocks
Capítulo: Episodic Remagnetizations related to tectonic events and their consequences
for the South America Polar Wander Path
Autores: Eric Font, Augusto E. Rapalini, Renata Tomezzoli, Ricardo Trindade, Eric Tohver
Resumen: The South American record of remagnetizations is linked to specific events
of its tectonic history stretching back to Precambrian times. At the
Ediacaran–Cambrian time interval (570–500 Ma), the final stages of the western
Gondwana assemblage led to remagnetization of Neoproterozoic carbonates within
the São Francisco–Congo Craton and at the border of the Amazon Craton, along
the Araguaia–Paraguay–Pampean Belt. From the late Permian to early Triassic, the
San Rafaelic orogeny and the emplacement of the Choiyoi magmatic province was
responsible for widespread remagnetizations in Argentina and Uruguay. Cretaceous
remagnetization has also been documented in Brazil and interpreted to result from
magmatism and fault reactivations linked to the opening of the South Atlantic Ocean.
We present a review of these widespread remagnetization events principally based
on palaeomagnetic data and, when available, on rock magnetic and radiogenic
isotope age data. This study gives an overview of the geographical distribution of
the remagnetization events in South America, and provides important clues to better
understand the geodynamic evolution of the South American plate at these times. In
addition, magnetic mineralogy data for the different case studies presented here
constrain the physical–chemical mechanisms that led to partial or total resetting of
magnetic remanences in sedimentary rocks.