| Texto completo | |
| Autor(es): |
Gengo, Rafaela Machado
;
Louro, Vinicius Hector Abud
;
Moraes, Renato
;
Szabo, Gergely Andres Julio
;
Dantas, Elton Luiz
;
Simoes, Pedro Machado
Número total de Autores: 6
|
| Tipo de documento: | Artigo Científico |
| Fonte: | Journal of South American Earth Sciences; v. 148, p. 19-pg., 2024-09-19. |
| Resumo | |
The Campo do Meio Shear Belt (CMSB) is an approximately 200 x 25 km transcurrent area along the south-southwest margin of the S & atilde;o Francisco Craton. A comprehensive review of geology was performed in the western CMSB, where rocks from the Campos Gerais and Pet & uacute;nia Complexes are predominant. The Campos Gerais Complex is relatively well positioned in the geotectonic context of the region. It corresponds to an Archean granite-greenstone belt lithological association related to the south-southwest part of the S & atilde;o Francisco Craton. The Pet & uacute;nia Complex, in contrast, is unraveled in this contribution through the integration of aerogeophysical data from the western Campo do Meio Shear Belt (CMSB) with new fieldwork observations and zircon U-Pb (LA-MC-ICP-MS) dating. The Pet & uacute;nia Complex has been restricted to two Mesoarchean gneissic units - Pet & uacute;nia and Ribeir & atilde;o da Conquista Gneiss, with crystallization ages of 2993 +/- 11 Ma and 2870 +/- 9 Ma, respectively. Although the ages are broadly coincident with those found in the Campos Gerais Complex, three characteristics suggest an evolutionary independent scenario (pre-S2) during the Archean for the Pet & uacute;nia and Campos Gerais Complexes: i) the sharp contrast in gamma-ray emissions between these complexes; ii) the absence of komatiite affiliation in the meta-ultramafic rocks from the Pet & uacute;nia Complex; and, iii) the absence of mafic dykes in the Pet & uacute;nia Complex. These two complexes also can be distinguished by the frequency of Paleoproterozoic granitoid intrusions. The Pet & uacute;nia Complex has only one occurrence, the Bom Jesus da Penha Metagranite, with a crystallization age of 2004 +/- 11 Ma. On the other hand, several Paleoproterozoic granitoid intrusions (2.0-1.9 Ga) have been found in the Campos Gerais Complex. These Orosirian granitoids are restricted to CMSB and younger than those in the Mineiro Belt. We suggest that these Orosirian granitoids may represent remnants of a collision event that occurred after 2.1 Ga, leading to the integration of the Pet & uacute;nia and Campo Gerais Complexes into the Columbia paleocontinent. During the Neoproterozoic, the evolution in the CMSBinvolved the cratonic basement and units related to the Southernmost Bras & iacute;lia Orogen. This set configures a tectonic m & eacute;lange that underwent progressive deformation in a non-coaxial, partitioned transpressional regime. (AU) | |
| Processo FAPESP: | 16/22627-3 - Metamorfismo e fusão parcial em Orógenos antigos II |
| Beneficiário: | Renato de Moraes |
| Modalidade de apoio: | Auxílio à Pesquisa - Regular |