| Texto completo | |
| Autor(es): |
Moreno, J. A.
;
Baldim, M. R.
;
Semprich, J.
;
Oliveira, E. P.
;
Verma, S. K.
;
Teixeira, W.
Número total de Autores: 6
|
| Tipo de documento: | Artigo Científico |
| Fonte: | Precambrian Research; v. 294, p. 322-343, JUN 2017. |
| Citações Web of Science: | 11 |
| Resumo | |
New LA-SF-ICP-MS U-Pb zircon dating of high-K granitoids from the Campo Belo metamorphic complex, southern Sao Francisco Craton (Brazil), reveals a long period (ca. 100 My) of Neoarchean granitic magmatism that post-date the TTG magmatism. The oldest studied pluton is a highly porphyritic biotite orthogneiss emplaced at 2748 +/- 5 Ma, followed by a hornblende-biotite orthogneiss (2727 +/- 7 Ma). Both granitic bodies were affected by a deformation event prior to the emplacement of the Rio do Amparo, Bom Sucesso and Lavras granitoid plutons at 2716 +/- 6 Ma, 2696 +/- 6 Ma and 2646 +/- 5 Ma, respectively. The Neoarchean granitic magmatism ended with the intrusion of peraluminous leucogranitic dikes at 2631 +/- 4 Ma. The 2.73-2.65 Ga Campo Belo granitoids share chemical features of A-type granites, such as high apatite- and zircon-saturation temperatures (mostly > 800 degrees C), relatively high Fe-number, high total alkalis and characteristic enrichment in LREE and HFSE although most samples of the Rio do Amparo granite have lower HFSE and LREE content that typical A-type granites but very high Th. The high Th content of the Rio do Amparo and Bom Sucesso granites may suggest involvement of Th-orthosilicate in their sources. The trace element composition permits to classify the Campo Belo granitoids as A(2)-type granites, suggesting derivation from partial melting of TTG-crustal sources likely in an extensional setting. Significant reworking of Mesoarchean crust is suggested by mostly negative epsilon Nd-i, values (Rio do Amparo: -2.0 and +3.1; Bom Sucesso: -3.6, -3.1 and +0.9; Lavras: -2.5 and -0.2) and old Nd model ages (T-DM close to 3.1 Ga), although with probable involvement of juvenile material (T-DM of 2.7-2.9 Ga). This contrasts with Neoarchean granites of the northern Sao Francisco and Congo cratons characterized by negligible juvenile imprint. The 2.75-2.63 Ga Campo Belo granitoids witness the thermal stabilization of the Archean lithosphere through a major episode of high-K granitoid magmatism between 2760 and 2600 Ma, which affected the whole Sao Francisco Craton and the northern Congo Craton. (C) 2017 Elsevier B.V. All rights reserved. (AU) | |
| Processo FAPESP: | 14/03334-0 - Origem de magmas TTG usando modelagem termodinâmica e de elementos traço |
| Beneficiário: | Julia Jennifer Semprich |
| Modalidade de apoio: | Bolsas no Brasil - Pós-Doutorado |
| Processo FAPESP: | 12/15824-6 - Evolução de terrenos arqueanos do Cráton São Francisco e Província Borborema: implicações para processos geodinâmicos e paleoambientais globais |
| Beneficiário: | Elson Paiva de Oliveira |
| Modalidade de apoio: | Auxílio à Pesquisa - Temático |
| Processo FAPESP: | 14/04920-0 - Investigações geológicas e geoquímicas em terrenos granito-gnaisses arqueanos do Cráton São Francisco |
| Beneficiário: | Juan Antonio Moreno Moreno |
| Modalidade de apoio: | Bolsas no Brasil - Pós-Doutorado |
| Processo FAPESP: | 12/07243-3 - Novos diagramas de discriminação multi-dimensionais e modelagem geoquímica aplicados a rochas ígneas arqueanas de cratons brasileiros |
| Beneficiário: | Sanjeet Kumar Verma |
| Modalidade de apoio: | Bolsas no Brasil - Pós-Doutorado |