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

Abstract

Apatite fission-track (AFT) analyses, applied to Southern Brazil and Uruguay samples, was employed aiming to understand the low temperature history of the Dom Feliciano Belt Segment. The Dom Feliciano Belt formed during the Neoproterozoic to Early Paleozoic, linked to the Brasiliano/Pan-African Orogeny. Twenty-four samples were dated, and confined track lengths of twenty samples were measured. The spatial distribution of ages shows three domains with different evolution cut by shear zones and, or suture zones in the Dom Feliciano Belt. The Western Domain exhibits AFT ages > 250 Ma (Permian to Devonian) while the Eastern Domain shows AFT 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, with cooling and reheating phases, and a denudation of ∼ 2600 m. The AFT ages clearly postdate the Gondwanide, Paraná-Etendeka and Rio Grande Cone exhumation history of the Dom Feliciano Belt.Published by Copernicus Publications on behalf of the European Geosciences Union.

Low-temperature thermochronology of the South Atlantic margin along Uruguay and its relation to tectonic events in West Gondwana

“…A plot of the MTLs against AFT central ages (Fig. 4), including published data (Kollenz 2015;Gomes & Almeida 2019), does not show a clear pe (Green 1986), which is characteristic of reheating with partial reset of AFT ages in a region.…”

“…1), where a very complex thermal history has been reported (Jelinek et al 2003;Karl et al 2013;Hueck et al 2018a). Further south of this region, thermochronometry studies have reported mainly pre-rift Paleozoic cooling phases in southernmost Brazil (Borba et al 2002(Borba et al , 2003Oliveira et al 2016;Machado et al 2019), Uruguay (Kollenz 2015;Hueck et al 2017;Gomes & Almeida 2019) and Argentina (Kollenz et al 2017). These were generally linked to Paleozoic orogenic cycles on the active SW margin of Gondwana and the geodynamics of Gondwana breakup.…”

“…Although passive margins and cratons are often considered as characterized by long-term stability, the low-temperature thermochronology studies in Uruguay indicate basement cooling since the early Paleozoic, suggesting a lengthy and complex Phanerozoic thermotectonic history. Available data suggest that the main exhumation event in the region was initiated well before Gondwana breakup (Kollenz 2015;Hueck et al 2017;Gomes & Almeida 2019). However, the current thermal histories modeled for the UYS by different authors and based on distinct thermochronometers (Kollenz 2015;Hueck et al 2017;Gomes & Almeida 2019) suggest alternative phases of cooling and reheating of the basement, and imply conflicting geodynamic models for the regional tectonic evolution.…”

“…Available data suggest that the main exhumation event in the region was initiated well before Gondwana breakup (Kollenz 2015;Hueck et al 2017;Gomes & Almeida 2019). However, the current thermal histories modeled for the UYS by different authors and based on distinct thermochronometers (Kollenz 2015;Hueck et al 2017;Gomes & Almeida 2019) suggest alternative phases of cooling and reheating of the basement, and imply conflicting geodynamic models for the regional tectonic evolution. The complex and scattered thermochronometry data in the region represent a restraint to our understanding of the tectonic activity preceding South Atlantic rifting and breakup.…”

Preface: Earth surveillance and space-based monitoring of the environment: integrated approaches

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