Episodic Remagnetizations in South America and Links to Tectonic Events

FONT, E.; RAPALINI, A.E.; TOMEZZOLI, R.N.; TRINDADE, R.I.F.; TOVHER, E.

JOURNAL OF THE GEOLOGICAL SOCIETY

GEOLOGICAL SOC PUBL HOUSE

Lugar: LOndres; Año: 2012 vol. 371 p. 1 - 50

0016-7649

The South American record of remagnetizations is linked to specific events in the tectonic history stretching back to Precambrian times. At the Ediacaran-Cambrian (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 belts. During the late Permian to early Triassic, the San Rafaelic orogen 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 Paraná flood basalt volcanism and fault reactivations linked to the opening of the South Atlantic Ocean. In this contribution, we present a review of these widespread remagnetization events. Our compilation is principally based on palaeomagnetic data and, when available, on rock magnetic and radiogenic isotope age data. It 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, aspects of magnetic mineralogy data in the different case studies presented here constrain the physical-chemical mechanisms that led to partial or total resetting of magnetic remanences in sedimentary rocks.