Cambrian mafic to felsic magmatism and its connections with transcurrent shear zones of the Borborema Province (NE Brazil): Implications for the late assembly of the West Gondwana

Autor(es)

Hollanda, Maria Helena B. M. ^[1] ; Archanjo, Carlos J. ^[1] ; Souza, Laecio C. ^[2] ; Armstrong, Richard ^[3] ; Vasconcelos, Paulo M. ^[4]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, IGc, BR-05508080 Sao Paulo - Brazil

^[2] Univ Fed Rio Grande do Norte, Dept Geol, BR-59078970 Natal, RN - Brazil

^[3] Australian Natl Univ, Res Sch Earth Sci, Canberra, ACT 0200 - Australia

^[4] Univ Queensland, Earth Sci Sch Phys Sci, Brisbane, Qld 4072 - Australia

• Tipo de documento: Artigo Científico
• Fonte: Precambrian Research; v. 178, n. 1-4, p. 1-14, APR 2010.
• Citações Web of Science: 21

Resumo

New U-Pb (SHRIMP) and (40)Ar/(39)Ar isotopic data of igneous rocks and mylonites of the Borborema Province (NE Brazil) show that a wide range of tectonothermal events affected the province during the transition from the Precambrian to the Cambrian. Concordant zircon U-Pb data constrained the crystallization age of mafic stocks, mafic to felsic dikes and granite batholiths between 548 and 533 Ma. These bodies were emplaced in a regional strain field combining extension and dextral shearing. The ductile shear deformation overprinted an older basement fabric to develop a low- to medium metamorphic grade vertical mylonite belt that cut the province in the E-W direction. Magnetic fabrics of the Cambrian batholiths determined by anisotropy of magnetic susceptibility are consistent with syntectonic emplacement. The magmatic pulses and shear deformation would have supplied enough heat to reset the synkinematic micas of mylonites to yield (40)Ar/(39)Ar plateau cooling ages between ca. 550 and 510 Ma. These results provide evidence that emplacement of Early Cambrian mafic and felsic magmas were accompanied by regional-scale shear deformations, probably in the consequence of late collisions along the West Gondwana margin. (C) 2010 Published by Elsevier B.V. (AU)

• Processo FAPESP: 04/08614-9 - O cambro-ordoviciano na província Borborema Oriental
• Beneficiário: Maria Helena Bezerra Maia de Hollanda
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores
• Processo FAPESP: 05/53144-3 - Estudo da deformação crustal utilizando modelos numéricos e suas relações com o alojamento de plútons graníticos
• Beneficiário: Carlos José Archanjo
• Modalidade de apoio: Bolsas no Exterior - Pesquisa