| Texto completo | |
| Autor(es): |
Frugis, Gabriella Labate
;
Campos Neto, Mario da Costa
;
Westin, Alice
;
Fanning, Christopher Mark
Número total de Autores: 4
|
| Tipo de documento: | Artigo Científico |
| Fonte: | Precambrian Research; v. 411, p. 21-pg., 2024-07-31. |
| Resumo | |
The Paraguay Belt and Brasilia Orogen, the western and eastern segments of the Tocantins Province, respectively, recorded the interactions among the Amazonian, Sao Francisco-Congo Craton, and Paranapanema Block during the amalgamation of Western Gondwana. The Paraguay Belt joins the Brasilia Orogen in the Transbrasiliano Lineament, which separates metasedimentary rocks to the west from metavolcano-sedimentary rocks to the east. This study focuses on four geological units cropping out in Brazil, between the Mato Grosso State southeastern region and the Goia<acute accent>s State western region: the Nova Xavantina Metavolcano-sedimentary Sequence (NXS), the Cuiaba<acute accent> Group (CG), the Barra do Gar & ccedil;as-Coxim Unit (BGCU), a newly identified register of foreland sedimentation, and the Bom Jardim de Goia<acute accent>s Metavolcano-sedimentary Sequence (BJGS). Whole-rock elemental geochemistry and Nd-Sr isotopes, along with zircon U-Pb-Hf-O systematics, provide insights into the evolution of this domain. Metavolcanic rocks from the NXS suggest that it represents a back-arc extensional tectonic environment with oceanic spreading (zircon age of ca. 710 Ma with delta 18O of 4.8 %o and chondritic epsilon Hf(t) formed along the southeastern edge of the Amazonian Craton. Metarenites preserve bimodal sources of ca. 0.85 Ga and ca. 1.90 Ga, while lithic metarenites exhibit Mesoproterozoic zircon grains suggesting sources from both the Amazonian Craton and the Paranapanema Block. The maximum depositional age of the lithic metarenites is ca. 715 Ma, coinciding with the age of the volcanic peak. The CG is interpreted as passive margin deposits through the erosion of depleted Mesoproterozoic (1.50-1.45 Ga and 1.23-1.17 Ga) and more evolved Paleoproterozoic (1.97-1.77 Ga) rocks from the Amazonian Craton. Metasedimentary rocks from the BGCU present age peaks of 800-600 Ma, recording the input of juvenile material into the basin as revealed by zircon grains of ca. 716 Ma and ca. 810 Ma with delta 18O of 4.7-4.8 %o and epsilon Hf(t) of + 7. These findings indicate Goia<acute accent>s Magmatic Arc juvenile sources and disclose the evolution of the unit towards a continental arc, as suggested by more evolved zircon grains younger than ca. 700 Ma. Gneisses of ca. 690-655 Ma occur as basement rocks of the BGCU and suggest prolongation of the Goia<acute accent>s Magmatic Arc westward within the Transbrasiliano corridor. (AU) | |
| Processo FAPESP: | 17/18174-6 - Proveniência sedimentar dos segmentos internos da Faixa Paraguai: domínios paleogeográficos distais de uma margem passiva? |
| Beneficiário: | Gabriella Labate Frugis |
| Modalidade de apoio: | Bolsas no Brasil - Doutorado |
| 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 |