Archean crustal evolution in the Southern São Francisco craton, Brazil: Constraints from U-Pb, Lu-Hf and O isotope analyses

In this study we present U–Pb and Hf isotope data combined with O isotopes in zircon from Neoarchean granitoids and gneisses of the southern São Francisco craton in Brazil. The basement rocks record three distinct magmatic events: Rio das Velhas I (2920–2850 Ma), Rio das Velhas II (2800–2760 Ma) and...

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Detalles Bibliográficos
Publicado: 2016
Materias:
Crustal evolution
Lu–Hf isotopes
O isotopes
São Francisco craton
U–Pb dating
Zircon
Archean
continental crust
crustal evolution
geodynamics
gneiss
granitoid
hafnium
isotopic analysis
lutetium
oxygen isotope
uranium-lead dating
zircon
Brazil
Sao Francisco Craton
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00244937_v266-267_n_p64_Albert
http://hdl.handle.net/20.500.12110/paper_00244937_v266-267_n_p64_Albert
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id paper:paper_00244937_v266-267_n_p64_Albert
record_format dspace
spelling paper:paper_00244937_v266-267_n_p64_Albert2025-07-30T17:34:13Z Archean crustal evolution in the Southern São Francisco craton, Brazil: Constraints from U-Pb, Lu-Hf and O isotope analyses Crustal evolution Lu–Hf isotopes O isotopes São Francisco craton U–Pb dating Zircon Archean continental crust crustal evolution geodynamics gneiss granitoid hafnium isotopic analysis lutetium oxygen isotope uranium-lead dating zircon Brazil Sao Francisco Craton In this study we present U–Pb and Hf isotope data combined with O isotopes in zircon from Neoarchean granitoids and gneisses of the southern São Francisco craton in Brazil. The basement rocks record three distinct magmatic events: Rio das Velhas I (2920–2850 Ma), Rio das Velhas II (2800–2760 Ma) and Mamona (2750–2680 Ma). The three sampled metamorphic complexes (Bação, Bonfim and Belo Horizonte) have distinct εHf vs. time arrays, indicating that they grew as separate terranes. Paleoarchean crust is identified as a source which has been incorporated into younger magmatic rocks via melting and mixing with younger juvenile material, assimilation and/or source contamination processes. The continental crust in the southern São Francisco craton underwent a change in magmatic composition from medium- to high-K granitoids in the latest stages, indicating a progressive HFSE enrichment of the sources that underwent anatexis in the different stages and possibly shallowing of the melting depth. Oxygen isotope data shows a secular trend towards high δ18O (up to 7.79‰) indicating the involvement of metasediments in the petrogenesis of the high potassium granitoids during the Mamona event. In addition, low δ18O values (down to 2.50‰) throughout the Meso- and Neoarchean emphasize the importance of meteoritic fluids in intra-crustal magmatism. We used hafnium isotope modelling from a compilation of detrital zircon compositions to constrain crustal growth rates and geodynamics from 3.50 to 2.65 Ga. The modelling points to a change in geodynamic process in the southern São Francisco craton at 2.9 Ga, from a regime dominated by net crustal growth in the Paleoarchean to a Neoarchean regime marked by crustal reworking. The reworking processes account for the wide variety of granitoid magmatism and are attributed to the onset of continental collision. © 2016 Elsevier B.V. 2016 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00244937_v266-267_n_p64_Albert http://hdl.handle.net/20.500.12110/paper_00244937_v266-267_n_p64_Albert
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic Crustal evolution
Lu–Hf isotopes
O isotopes
São Francisco craton
U–Pb dating
Zircon
Archean
continental crust
crustal evolution
geodynamics
gneiss
granitoid
hafnium
isotopic analysis
lutetium
oxygen isotope
uranium-lead dating
zircon
Brazil
Sao Francisco Craton
spellingShingle Crustal evolution
Lu–Hf isotopes
O isotopes
São Francisco craton
U–Pb dating
Zircon
Archean
continental crust
crustal evolution
geodynamics
gneiss
granitoid
hafnium
isotopic analysis
lutetium
oxygen isotope
uranium-lead dating
zircon
Brazil
Sao Francisco Craton
Archean crustal evolution in the Southern São Francisco craton, Brazil: Constraints from U-Pb, Lu-Hf and O isotope analyses
topic_facet Crustal evolution
Lu–Hf isotopes
O isotopes
São Francisco craton
U–Pb dating
Zircon
Archean
continental crust
crustal evolution
geodynamics
gneiss
granitoid
hafnium
isotopic analysis
lutetium
oxygen isotope
uranium-lead dating
zircon
Brazil
Sao Francisco Craton
description In this study we present U–Pb and Hf isotope data combined with O isotopes in zircon from Neoarchean granitoids and gneisses of the southern São Francisco craton in Brazil. The basement rocks record three distinct magmatic events: Rio das Velhas I (2920–2850 Ma), Rio das Velhas II (2800–2760 Ma) and Mamona (2750–2680 Ma). The three sampled metamorphic complexes (Bação, Bonfim and Belo Horizonte) have distinct εHf vs. time arrays, indicating that they grew as separate terranes. Paleoarchean crust is identified as a source which has been incorporated into younger magmatic rocks via melting and mixing with younger juvenile material, assimilation and/or source contamination processes. The continental crust in the southern São Francisco craton underwent a change in magmatic composition from medium- to high-K granitoids in the latest stages, indicating a progressive HFSE enrichment of the sources that underwent anatexis in the different stages and possibly shallowing of the melting depth. Oxygen isotope data shows a secular trend towards high δ18O (up to 7.79‰) indicating the involvement of metasediments in the petrogenesis of the high potassium granitoids during the Mamona event. In addition, low δ18O values (down to 2.50‰) throughout the Meso- and Neoarchean emphasize the importance of meteoritic fluids in intra-crustal magmatism. We used hafnium isotope modelling from a compilation of detrital zircon compositions to constrain crustal growth rates and geodynamics from 3.50 to 2.65 Ga. The modelling points to a change in geodynamic process in the southern São Francisco craton at 2.9 Ga, from a regime dominated by net crustal growth in the Paleoarchean to a Neoarchean regime marked by crustal reworking. The reworking processes account for the wide variety of granitoid magmatism and are attributed to the onset of continental collision. © 2016 Elsevier B.V.
title Archean crustal evolution in the Southern São Francisco craton, Brazil: Constraints from U-Pb, Lu-Hf and O isotope analyses
title_short Archean crustal evolution in the Southern São Francisco craton, Brazil: Constraints from U-Pb, Lu-Hf and O isotope analyses
title_full Archean crustal evolution in the Southern São Francisco craton, Brazil: Constraints from U-Pb, Lu-Hf and O isotope analyses
title_fullStr Archean crustal evolution in the Southern São Francisco craton, Brazil: Constraints from U-Pb, Lu-Hf and O isotope analyses
title_full_unstemmed Archean crustal evolution in the Southern São Francisco craton, Brazil: Constraints from U-Pb, Lu-Hf and O isotope analyses
title_sort archean crustal evolution in the southern são francisco craton, brazil: constraints from u-pb, lu-hf and o isotope analyses
publishDate 2016
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00244937_v266-267_n_p64_Albert
http://hdl.handle.net/20.500.12110/paper_00244937_v266-267_n_p64_Albert
_version_ 1840322816060162048

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