Contrasting thermal histories in the Dom Feliciano Belt triggered by magmatism related to the Paraná-Etendeka LIP and fracture zone proximity

Abstract

The present-day southern Brazilian continental margin rests on top of the Dom Feliciano Belt (DFB) and adjacent cratons. This belt formed through the collision of the Rio de La Plata, Kalahari, Paranapanema, Congo and Luis Alves paleoplates in the Neoproterozoic. Several low-temperature thermochronology works were executed in the area, although none of them demonstrated how the basement temperature of the entire DFB evolved through time. To this end, this work aims to provide new Apatite Fission Track (AFT) and Apatite (U–Th)/He (AHe) ages for samples collected in the Catarinense Shield, in the northern DFB, and to perform inverse modeling in those samples. Besides, the collection of the basement temperature of 128 locations across the entire belt and adjacent cratons provided thermal information to create inverse-distance weighted interpolation maps documenting the progression of the temperature from 360 to 30 Ma. New AFT ages range from 126.6 ± 24.1 to 60.3 ± 6.03 Ma, whereas AHe ages span from 153.0 ± 9.2 to 62.5 ± 3.7 Ma. Mean track lengths are short to medium, suggesting complete thermal annealing of apatite crystals. Apatite single-grain eU concentration range from 4.5 to 96 μg/g and display a sparse correlation with AHe ages. Interpolation maps evidence a contrasting temperature evolution of the northern DFB and bordering cratons relative to the southern segment and surrounding cratons. Nearsurface exposure of the basement in the northern segment was possibly much earlier than in the south, followed by partial burial by the sedimentary successions of the Paran´ a Basin. The emplacement of volcanic rocks of the Paran´ a-Etendeka Large Igneous Province and associated dyke swarms and alkaline volcanic plugs related to the Florianopolis ´ Fracture Zone raised and sustained higher basement temperatures until 30 Ma, resetting lowtemperature thermochronometers in the northern DFB, which was minor to absent in the southern DFB.