Post‐breakup tectonics in southeast Brazil from thermochronological data and combined inverse‐forward thermal history modeling

Abstract

[1] The continental margin of southeast Brazil is elevated. Onshore Tertiary basins and Late Cretaceous/Paleogene intrusions are good evidence for post breakup tectono-magmatic activity. To constrain the impact of post-rift reactivation on the geological history of the area, we carried out a new thermochronological study. Apatite fission track ages range from 60.7 AE 1.9 Ma to 129.3 AE 4.3 Ma, mean track lengths from 11.41 AE 0.23 mm to 14.31 AE 0.24 mm and a subset of the (U-Th)/He ages range from 45.1 AE 1.5 to 122.4 AE 2.5 Ma. Results of inverse thermal history modeling generally support the conclusions from an earlier study for a Late Cretaceous phase of cooling. Around the onshore Taubaté Basin, for a limited number of samples, the first detectable period of cooling occurred during the Early Tertiary. The inferred thermal histories for many samples also imply subsequent reheating followed by Neogene cooling. Given the uncertainty of the inversion results, we did deterministic forward modeling to assess the range of possibilities of this Tertiary part of the thermal history. The evidence for reheating seems to be robust around the Taubaté Basin, but elsewhere the data cannot discriminate between this and a less complex thermal history. However, forward modeling results and geological information support the conclusion that the whole area underwent cooling during the Neogene. The synchronicity of the cooling phases with Andean tectonics and those in NE Brazil leads us to assume a plate-wide compressional stress that reactivated inherited structures. The present-day topographic relief of the margin reflects a contribution from post-breakup reactivation and uplift.Citation: Cogné, N., K. Gallagher, P. R. Cobbold, C. Riccomini, and C. Gautheron (2012), Post-breakup tectonics in southeast Brazil from thermochronological data and combined inverse-forward thermal history modeling,

Synorogenic foreland rifts and transtensional basins: A review of Andean imprints on the evolution of the San Jorge Gulf, Salta Group and Taubaté Basins

“…For the case of the Salta Group Basin, we revised and compared the main Andean orogenic stages of Northern Chile with the evolutionary stages of the transversal Olmedo Sub-basin of the Salta Group Basin. A similar approach has been used by several authors to diagnose contraction-induced extensional/transtensional reactivations in South America (Cobbold et al, 2001, Cogné et al, 2012, 2013, Gianni et al, 2014, Ramos, 2014 as well as in Asia (Mats and Perelepova, 2011).…”

“…Independently, deformational events recognized in SE Brazil and particularly for the Campanian in the NE of Brazil were associated with widespread cooling events (Viviers and Azevedo, 1988, Cobbold et al, 2001, 2010, Zalán and Oliveira, 2005, Japsen et al, 2012, Cogné et al, 2011, 2013. In the Taubate Basin, plate-wide compression caused folding of basement rocks and fast cooling in Late Cretaceous, revealed in the light of seismic and thermochronological data (Cogné et al, 2011(Cogné et al, , 2012(Cogné et al, , 2013 (Fig.14).…”

“…We made a review of the latest advances in the San Jorge Gulf and Taubaté Basins that highlighted the important role of Andean far-field stress on their evolution (Cobbold et al, 2001, Cogné et al, 2012, 2013, Gianni et al, 2014, Ramos, 2014. For the case of the Salta Group Basin, we revised and compared the main Andean orogenic stages of Northern Chile with the evolutionary stages of the transversal Olmedo Sub-basin of the Salta Group Basin.…”

“…Cobbold et al, (2001) and Cogné et al, (2011Cogné et al, ( , 2012 showed that each basin reactivation corresponded to a fast cooling event revealed through thermochronological data (100 to 70 Ma, 60-45 Ma and 15 Ma) and that each event was coincident with main Andean orogenic phases registered to the west (ie: Peruvian, Incaic and Quechua phases) (Fig.13). In this sense, Cogné et al, (2013) suggested that the Taubaté Basin developed in response to NE directed Incaic compression inferred from the oblique angle of plate convergence at that time.…”

História termotectônica da margem continental brasileira a partir de dados de traços de fissão em apatita

“…A reativação tectônica Cenozoica do embasamento continental e consequente formação de Riftes Cenozoicos também é sugerido por outros autores na margem sudeste (p. ex., Hiruma et al, 2010;Cogné et al, 2012;Karl et al, 2013;Engelmann de Oliveira et al, 2016). Ao contrário da margem sudeste, a margem nordeste, na região do Cráton São Francisco, registra idades TFA mais antigas e um episódio térmico durante o Permiano e Jurássico Inferior, reflexo da Orogenia Gondwanide como sugerido por Jelinek et al (2014).…”