New insights into the Gondwana breakup at the Southern South America by apatite fission-track analyses

摘要

Abstract. Apatite fission-track?(AFT) analyses, applied to Southern Braziland Uruguay samples, was employed aiming to understand the low temperaturehistory of the Dom Feliciano Belt Segment. The Dom Feliciano Belt formedduring the Neoproterozoic to Early Paleozoic, linked to theBrasiliano/Pan-African Orogeny. Twenty-four samples were dated, and confinedtrack lengths of twenty samples were measured. The spatial distribution ofages shows three domains with different evolution cut by shear zones and, orsuture zones in the Dom Feliciano Belt. The Western Domain exhibits AFT ages> 250 Ma (Permian to Devonian) while the Eastern Domain showsAFT ages < 230 Ma (Paleogene to Triassic). In the Central Domain,the AFT ages range from ～196 to 130 Ma (Jurassic to Early Cretaceous).The thermal modeling in the domains revealed a complex evolution, withcooling and reheating phases, and a denudation of ～2600 m. The AFT agesclearly postdate the Gondwanide, Paraná-Etendeka and Rio Grande Coneexhumation history of the Dom Feliciano Belt.