Unravelling major magmatic episodes from metamorphic sequences of the Dom Feliciano Belt central sector, southernmost Brazil - A comparative study of geochronology, elemental geochemistry, and Sr-Nd data

The geochemical and isotopic signatures of magmatic events preserved in deformed metavolcano-sedimentary sequences may inform about geological setting and original basin stratigraphy. This paper discusses elemental and isotopic geochemical literature data on metavolcanic rocks interleaved with highly-deformed metasedi-mentary rocks from the Dom Feliciano Belt central sector, southernmost Brazil: the high-grade V acute accent arzea do Cap-ivarita, and the lower greenschist to amphibolite facies Porongos and Passo Feio complexes. We also provide new geochemical data for seven samples and two U-Pb zircon determinations. REE patterns, together with geochronological data, permit to sort the dataset into three main groups: i) Group 1 -LaN/YbN approximate to 10, Eu/Eu* = 0.38 to 0.86; ii) Group 2 -LaN/YbN = 12 to 44, no Eu anomaly, and iii) Group 3 -negative Eu anomaly (Eu/Eu* approximate to 0.70), but higher LREEs absolute values (LaN/YbN approximate to 22), and rare basic metavolcaniclastic rocks (Bmvc). New U-Pb zircon analyses of two Passo Feio acidic metavolcanic rocks yield a crystallization age of 580 +/- 2 Ma (2 Sigma). Group 1 samples account for a magmatic event at 800-770 Ma in the V acute accent arzea do Capivarita and Porongos (Cerro da acute accent Arvore sequence) complexes. They represent a magmatic association produced from subduction-related sources, with crustal contribution shown by 87Sr/86Sr(790 Ma) > 0.715 and sigma Nd(790 Ma) from-5 and-11 (up to -22). Groups 2 and 3 account for a magmatic event at ca. 600 to 580 Ma in the Passo Feio and western Porongos (Capane acute accent sequence) complexes. Groups 2 and 3 rocks are interpreted to have been sourced from subduction-related enriched mantle without major crustal contamination, with 87Sr/86Sr(580 Ma) = 0.7035-0.7050 and sigma Nd(580 Ma) >-10. For the basic metavolcanoclastic sample (Bmvc), the data suggest mantle -derived origin without significant contribution of subduction-related sources, possibly indicating multiple sources for this newly-described and not yet fully understood Ediacaran magmatism. Our comparative study leads to the novel conclusion of a shared tectonic evolution between the Passo Feio Complex and the western Porongos Complex at ca. 600-580 Ma. They also corroborate a shared tectonic evolution between the Porongos Complex and V acute accent arzea do Capivarita Complex at ca. 800-770 Ma, as reported by previous authors.

Automated summary

This paper discusses the geochemical and isotopic signatures of magmatic events preserved in deformed metavolcano-sedimentary sequences in southernmost Brazil. It presents new geochemical data and geochronological analysis of the rocks, classifying them into different groups based on their REE patterns and isotopic composition. The study reveals a shared tectonic evolution between different complexes at different time periods, providing insights into the geological setting and original basin stratigraphy.