| Texto completo | |
| Autor(es): |
Lino, Lucas Martins
;
Quiroz-Valle, Francy Roxana
;
Vlach, Silvio Roberto Farias
;
Basei, Miguel Angelo Stipp
;
Vilalva, Frederico Castro Jobim
;
Hueck, Mathias
;
Martins, Jose Vinicius
Número total de Autores: 7
|
| Tipo de documento: | Artigo Científico |
| Fonte: | CHEMICAL GEOLOGY; v. 635, p. 20-pg., 2023-09-30. |
| Resumo | |
The Ediacaran Campo Alegre-Corup & PRIME;a Basin (CACB) comprises a rare and excellent exposure of caldera-forming pyroclastic rocks and their cogenetic underlaying plutons. The CACB experienced at least two major episodes of bimodal volcanic activity. The Basin Stage (-605-590 Ma), characterized by transitional OIB-like basaltic lava flows with minor trachydacites and rhyolites, interbedded with surge-like, silicic pyroclastic deposits, and the Caldera Stage (-583-577 Ma), marked by at least one cycle of silicic alkaline, caldera-forming eruption, dominated by rhyolitic to trachytic ignimbrites and lava flows/domes with subordinate IAB-like basalts. During the Caldera Stage, granitoid plutons were emplaced at shallow crustal levels (-5-8 km deep), correlating with the depth of the magma chamber responsible for the contemporaneous large silicic eruption(s). Previous studies have suggested a genetic connection between the post-collisional volcanic and plutonic rocks based on their similar ages, composition, and Sr-Nd-Hf isotopic signatures. In this study, we analyze zircon trace elements from the volcanic rocks of both stages in the CACB to constrain their evolutive compositional patterns, redox conditions, and Ti-in-zircon saturation temperatures. We compare our results with zircon compositions of the cogenetic granitoids, focusing on the Corup & PRIME;a Pluton, which likely supplied the magma for the caldera-forming eruption(s). By examining whole-rock and zircon chemical compositions, we establish a petrogenetic link between the volcanic rocks and their potential remnant magma reservoir. Our findings indicate that the silicic volcanic rocks from the Caldera Stage represent highly evolved compositions extracted from a crystal mush that solidified as a syenitic intrusion. During the evolution of the volcanic-plutonic system, zircon crystals tracked compositional changes associated with the extraction of residual silicic liquids from crystal mushes and the formation of intermediate-silicic cumulates. Unique variations in zircon compositions of volcanic and plutonic rocks, such as Eu/Eu*, Zr/Hf, and Th/U ratios support such a connection and suggest crystal-melt segregation processes at relatively low crystallinities (< 30 vol%). Additionally, our trace element data supports the occurrence of intense hydrothermal-induced recrystallization of zircon within the caldera structure, as suggested by the morphologic aspects of crystals previously analyzed for U-Pb and Lu-Hf isotopes. (AU) | |
| Processo FAPESP: | 19/17343-4 - Propriedades geoquímicas e texturais de minerais acessórios como indicadoras petrológicas e geocronológicas em rochas graníticas e greisens associados |
| Beneficiário: | Silvio Roberto Farias Vlach |
| Modalidade de apoio: | Auxílio à Pesquisa - Regular |
| Processo FAPESP: | 15/03737-0 - O Cráton Rio de la Plata e o Gondwana Ocidental |
| Beneficiário: | Miguel Angelo Stipp Basei |
| Modalidade de apoio: | Auxílio à Pesquisa - Temático |
| Processo FAPESP: | 19/06838-2 - Zonas de cisalhamento Brasilianas/Pan-Africanas no Cinturão Kaoko e conexões com a América do Sul: evolução Neoproterozoica e reativações fanerozoicas |
| Beneficiário: | Mathias Hueck |
| Modalidade de apoio: | Bolsas no Brasil - Pós-Doutorado |