Petrologic and geochronological constraints on the polymetamorphic evolution of the collisional granites, Araçuaí Orogen (SE Brazil)
Abstract Collisional granites of the Araçuaí Orogen, southeastern Brazil, record petrological and geochronological evidence for multiple crustal melting during the orogeny evolution. U-Pb zircon data indicate that these granites crystallized at 586 ± 2 M.y. High-grade metamorphism (M1) involved part...
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Academia Brasileira de Ciências
2021-10-01
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| Series: | Anais da Academia Brasileira de Ciências |
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| Online Access: | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652021000501104&tlng=en |
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| author | SANDRO MAURI MARILANE G. MELO CRISTIANO LANA RODSON A. MARQUES |
| author_facet | SANDRO MAURI MARILANE G. MELO CRISTIANO LANA RODSON A. MARQUES |
| author_sort | SANDRO MAURI |
| collection | DOAJ |
| description | Abstract Collisional granites of the Araçuaí Orogen, southeastern Brazil, record petrological and geochronological evidence for multiple crustal melting during the orogeny evolution. U-Pb zircon data indicate that these granites crystallized at 586 ± 2 M.y. High-grade metamorphism (M1) involved partial melting by fluid-absent reactions that produced the first generation of garnet in temperatures of approx. 750°C. Preservation of the mineral assemblage A1 (garnet-biotite-plagioclase-K-feldspar-quartz-ilmenite-melt) indicates that most of the generated melt was lost from these rocks at or near peak metamorphic conditions. A second metamorphic event (M2) is characterized by growth of a second generation of garnet in preserved A2 assemblage (garnet-sillimanite-biotite-plagioclase-K-feldspar-quartz-ilmenite-melt). Mineral equilibria modeling constrains conditions of M2 metamorphism to 713-729 °C and 6.2-7.3 kbar. Retrograde assemblage (A3) records equilibrium conditions at 610-660 °C. The Hf isotope composition indicates significant crustal contribution to the genesis of the collisional granites. The elevated geotherms in thickened crust provide enough heat for the M1 event at 562 ± 2 M.y. Subsequent heating probably associated to the transfer of mantle heat to the crust during the extensional thinning and gravitational collapse of the orogen lead to the M2 event at 526 ± 4 M.y. This event is concomitant to the emplacement of the post-collisional magmas in the orogen. |
| first_indexed | 2024-04-11T15:29:53Z |
| format | Article |
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| institution | Directory Open Access Journal |
| issn | 1678-2690 |
| language | English |
| last_indexed | 2024-04-11T15:29:53Z |
| publishDate | 2021-10-01 |
| publisher | Academia Brasileira de Ciências |
| record_format | Article |
| series | Anais da Academia Brasileira de Ciências |
| spelling | doaj.art-4ab39a6539854e32bea09b10fdc41f1b2022-12-22T04:16:10ZengAcademia Brasileira de CiênciasAnais da Academia Brasileira de Ciências1678-26902021-10-0193310.1590/0001-3765202120200639Petrologic and geochronological constraints on the polymetamorphic evolution of the collisional granites, Araçuaí Orogen (SE Brazil)SANDRO MAURIhttps://orcid.org/0000-0002-6147-1370MARILANE G. MELOhttps://orcid.org/0000-0003-3397-3258CRISTIANO LANAhttps://orcid.org/0000-0001-6302-9706RODSON A. MARQUEShttps://orcid.org/0000-0003-3839-305XAbstract Collisional granites of the Araçuaí Orogen, southeastern Brazil, record petrological and geochronological evidence for multiple crustal melting during the orogeny evolution. U-Pb zircon data indicate that these granites crystallized at 586 ± 2 M.y. High-grade metamorphism (M1) involved partial melting by fluid-absent reactions that produced the first generation of garnet in temperatures of approx. 750°C. Preservation of the mineral assemblage A1 (garnet-biotite-plagioclase-K-feldspar-quartz-ilmenite-melt) indicates that most of the generated melt was lost from these rocks at or near peak metamorphic conditions. A second metamorphic event (M2) is characterized by growth of a second generation of garnet in preserved A2 assemblage (garnet-sillimanite-biotite-plagioclase-K-feldspar-quartz-ilmenite-melt). Mineral equilibria modeling constrains conditions of M2 metamorphism to 713-729 °C and 6.2-7.3 kbar. Retrograde assemblage (A3) records equilibrium conditions at 610-660 °C. The Hf isotope composition indicates significant crustal contribution to the genesis of the collisional granites. The elevated geotherms in thickened crust provide enough heat for the M1 event at 562 ± 2 M.y. Subsequent heating probably associated to the transfer of mantle heat to the crust during the extensional thinning and gravitational collapse of the orogen lead to the M2 event at 526 ± 4 M.y. This event is concomitant to the emplacement of the post-collisional magmas in the orogen.http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652021000501104&tlng=enAraçuaí Orogenpartial meltingpseudosectionU-Pb zirconcollisional graniterecycling |
| spellingShingle | SANDRO MAURI MARILANE G. MELO CRISTIANO LANA RODSON A. MARQUES Petrologic and geochronological constraints on the polymetamorphic evolution of the collisional granites, Araçuaí Orogen (SE Brazil) Anais da Academia Brasileira de Ciências Araçuaí Orogen partial melting pseudosection U-Pb zircon collisional granite recycling |
| title | Petrologic and geochronological constraints on the polymetamorphic evolution of the collisional granites, Araçuaí Orogen (SE Brazil) |
| title_full | Petrologic and geochronological constraints on the polymetamorphic evolution of the collisional granites, Araçuaí Orogen (SE Brazil) |
| title_fullStr | Petrologic and geochronological constraints on the polymetamorphic evolution of the collisional granites, Araçuaí Orogen (SE Brazil) |
| title_full_unstemmed | Petrologic and geochronological constraints on the polymetamorphic evolution of the collisional granites, Araçuaí Orogen (SE Brazil) |
| title_short | Petrologic and geochronological constraints on the polymetamorphic evolution of the collisional granites, Araçuaí Orogen (SE Brazil) |
| title_sort | petrologic and geochronological constraints on the polymetamorphic evolution of the collisional granites aracuai orogen se brazil |
| topic | Araçuaí Orogen partial melting pseudosection U-Pb zircon collisional granite recycling |
| url | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652021000501104&tlng=en |
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