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

0566491 - GLÚ 2024 RIV NL eng J - Článek v odborném periodiku
Battisti, M. A. - Bitencourt, M. d. F. - Florisbal, L. M. - Nardi, L. V. S. - Ackerman, Lukáš - Sláma, Jiří - Padilha, D. F.
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.
Precambrian Research. Roč. 385, February 2023 (2023), č. článku 106951. ISSN 0301-9268. E-ISSN 1872-7433
Institucionální podpora: RVO:67985831
Klíčová slova: Metavolcanic rocks * Magmatic events * Sr-Nd isotopes * U-Pb zircon dating * Dom Feliciano Belt * Reconstruction of ancient geological settings
Obor OECD: Geology
Impakt faktor: 3.8, rok: 2022
Způsob publikování: Omezený přístup
https://www.sciencedirect.com/science/article/pii/S0301926822003953

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 metasedimentary rocks from the Dom Feliciano Belt central sector, southernmost Brazil: the high-grade Várzea do Capivarita, 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 ≈ 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* ≈ 0.70), but higher LREEs absolute values (LaN/YbN ≈ 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 (2σ). Group 1 samples account for a magmatic event at 800–770 Ma in the Várzea do Capivarita and Porongos (Cerro da Árvore sequence) complexes. They represent a magmatic association produced from subduction-related sources, with crustal contribution shown by ⁸⁷Sr/⁸⁶Sr_{(790 Ma)} > 0.715 and ƐNd_{(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 (Capané 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 ƐNd_{(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 Várzea do Capivarita Complex at ca. 800–770 Ma, as reported by previous authors.


Trvalý link: https://hdl.handle.net/11104/0339026