High-pressure metamorphic rocks in the Borborema Province, Northeast Brazil: Reworking of Archean oceanic crust during proterozoic orogenies
We present the first evidence of Archean oceanic crust submitted to Proterozoic high-pressure (HP) metamorphism in the South American Platform. Sm–Nd and Lu–Hf isotopic data combined with U–Pb geochronological data from the Campo Grande area, Rio Grande do Norte domain, in the Northern Borborema Pro...
| Main Authors: | , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2020-11-01
|
| Series: | Geoscience Frontiers |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S1674987120300633 |
| _version_ | 1797726309109989376 |
|---|---|
| author | Alanielson da Câmara Dantas Ferreira Elton Luiz Dantas Ticiano José Saraiva dos Santos Reinhardt A. Fuck Mahyra Tedeschi |
| author_facet | Alanielson da Câmara Dantas Ferreira Elton Luiz Dantas Ticiano José Saraiva dos Santos Reinhardt A. Fuck Mahyra Tedeschi |
| author_sort | Alanielson da Câmara Dantas Ferreira |
| collection | DOAJ |
| description | We present the first evidence of Archean oceanic crust submitted to Proterozoic high-pressure (HP) metamorphism in the South American Platform. Sm–Nd and Lu–Hf isotopic data combined with U–Pb geochronological data from the Campo Grande area, Rio Grande do Norte domain, in the Northern Borborema Province, reflect a complex Archean (2.9 Ga and 2.6 Ga) and Paleoproterozoic (2.0 Ga) evolution, culminating in the Neoproterozoic Brasiliano/Pan-African orogeny (ca. 600 Ma). The preserved mafic rocks contain massive poikiloblastic garnet and granoblastic amphibole with variable proportions of plagioclase + diopside in symplectitic texture, typical of high-pressure rocks. These clinopyroxene-garnet amphibolites and the more common garnet amphibolites from the Campo Grande area are exposed as rare lenses within an Archean migmatite complex. The amphibolite lenses represent 2.65 Ga juvenile tholeiitic magmatism derived from depleted mantle sources (positive εHf(t) values of +3.81 to +30.66) later enriched by mantle metasomatism (negative εNd(t) values of –7.97). Chondrite and Primitive Mantle-normalized REE of analyzed samples and discriminant diagrams define two different oceanic affinities, with E-MORB and OIB signature. Negative Eu anomalies (Eu/Eu∗ = 0.75–0.95) indicate depletion of plagioclase in the source. Inherited zircon cores of 3.0–2.9 Ga in analyzed samples indicate that the Neoarchean tholeiitic magmatism was emplaced into 2923 ± 14 Ma old Mesoarchean crust (εNd(t) = –2.58 and Nd TDM = 3.2 Ga) of the Rio Grande do Norte domain. The age of retro-eclogite facies metamorphism is not yet completely understood. We suggest that two high-grade metamorphic events are recognized in the mafic rocks: the first at 2.0 Ga, recorded in some samples, and the second, at ca. 600 Ma, stronger and more pervasive and recorded in several of the mafic rock samples. The Neoproterozoic zircon grains are found in symplectite texture as inclusions in the garnet grains and represent the age of HP conditions in the area. These zircon grains show a younger cluster of concordant analyses between 623 ± 3 Ma and 592 ± 5 Ma with εHf(t) values of +0.74 to –65.88. Thus, the Campo Grande rock assemblage is composed of Archean units that were amalgamated to West Gondwana during Neoproterozoic Brasiliano orogeny continent-continent collision and crustal reworking. |
| first_indexed | 2024-03-12T10:43:45Z |
| format | Article |
| id | doaj.art-975f480da7d046299fa5f74292e05c4d |
| institution | Directory Open Access Journal |
| issn | 1674-9871 |
| language | English |
| last_indexed | 2024-03-12T10:43:45Z |
| publishDate | 2020-11-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Geoscience Frontiers |
| spelling | doaj.art-975f480da7d046299fa5f74292e05c4d2023-09-02T07:52:08ZengElsevierGeoscience Frontiers1674-98712020-11-0111622212242High-pressure metamorphic rocks in the Borborema Province, Northeast Brazil: Reworking of Archean oceanic crust during proterozoic orogeniesAlanielson da Câmara Dantas Ferreira0Elton Luiz Dantas1Ticiano José Saraiva dos Santos2Reinhardt A. Fuck3Mahyra Tedeschi4Instituto de Geociências, Universidade de Brasília (UnB), 70910-900, Brasília-DF, Brazil; Corresponding author.Instituto de Geociências, Universidade de Brasília (UnB), 70910-900, Brasília-DF, BrazilInstituto de Geociências, Universidade Estadual de Campinas (UNICAMP), Departamento de Geologia e Recursos Naturais, 13083-970, Campinas-SP, BrazilInstituto de Geociências, Universidade de Brasília (UnB), 70910-900, Brasília-DF, BrazilInstituto de Geociências, Universidade Federal de Minas Gerais (UFMG), 31270-901, Belo Horizonte, MG, BrazilWe present the first evidence of Archean oceanic crust submitted to Proterozoic high-pressure (HP) metamorphism in the South American Platform. Sm–Nd and Lu–Hf isotopic data combined with U–Pb geochronological data from the Campo Grande area, Rio Grande do Norte domain, in the Northern Borborema Province, reflect a complex Archean (2.9 Ga and 2.6 Ga) and Paleoproterozoic (2.0 Ga) evolution, culminating in the Neoproterozoic Brasiliano/Pan-African orogeny (ca. 600 Ma). The preserved mafic rocks contain massive poikiloblastic garnet and granoblastic amphibole with variable proportions of plagioclase + diopside in symplectitic texture, typical of high-pressure rocks. These clinopyroxene-garnet amphibolites and the more common garnet amphibolites from the Campo Grande area are exposed as rare lenses within an Archean migmatite complex. The amphibolite lenses represent 2.65 Ga juvenile tholeiitic magmatism derived from depleted mantle sources (positive εHf(t) values of +3.81 to +30.66) later enriched by mantle metasomatism (negative εNd(t) values of –7.97). Chondrite and Primitive Mantle-normalized REE of analyzed samples and discriminant diagrams define two different oceanic affinities, with E-MORB and OIB signature. Negative Eu anomalies (Eu/Eu∗ = 0.75–0.95) indicate depletion of plagioclase in the source. Inherited zircon cores of 3.0–2.9 Ga in analyzed samples indicate that the Neoarchean tholeiitic magmatism was emplaced into 2923 ± 14 Ma old Mesoarchean crust (εNd(t) = –2.58 and Nd TDM = 3.2 Ga) of the Rio Grande do Norte domain. The age of retro-eclogite facies metamorphism is not yet completely understood. We suggest that two high-grade metamorphic events are recognized in the mafic rocks: the first at 2.0 Ga, recorded in some samples, and the second, at ca. 600 Ma, stronger and more pervasive and recorded in several of the mafic rock samples. The Neoproterozoic zircon grains are found in symplectite texture as inclusions in the garnet grains and represent the age of HP conditions in the area. These zircon grains show a younger cluster of concordant analyses between 623 ± 3 Ma and 592 ± 5 Ma with εHf(t) values of +0.74 to –65.88. Thus, the Campo Grande rock assemblage is composed of Archean units that were amalgamated to West Gondwana during Neoproterozoic Brasiliano orogeny continent-continent collision and crustal reworking.http://www.sciencedirect.com/science/article/pii/S1674987120300633Archean oceanic crustProterozoic orogensBorborema province |
| spellingShingle | Alanielson da Câmara Dantas Ferreira Elton Luiz Dantas Ticiano José Saraiva dos Santos Reinhardt A. Fuck Mahyra Tedeschi High-pressure metamorphic rocks in the Borborema Province, Northeast Brazil: Reworking of Archean oceanic crust during proterozoic orogenies Geoscience Frontiers Archean oceanic crust Proterozoic orogens Borborema province |
| title | High-pressure metamorphic rocks in the Borborema Province, Northeast Brazil: Reworking of Archean oceanic crust during proterozoic orogenies |
| title_full | High-pressure metamorphic rocks in the Borborema Province, Northeast Brazil: Reworking of Archean oceanic crust during proterozoic orogenies |
| title_fullStr | High-pressure metamorphic rocks in the Borborema Province, Northeast Brazil: Reworking of Archean oceanic crust during proterozoic orogenies |
| title_full_unstemmed | High-pressure metamorphic rocks in the Borborema Province, Northeast Brazil: Reworking of Archean oceanic crust during proterozoic orogenies |
| title_short | High-pressure metamorphic rocks in the Borborema Province, Northeast Brazil: Reworking of Archean oceanic crust during proterozoic orogenies |
| title_sort | high pressure metamorphic rocks in the borborema province northeast brazil reworking of archean oceanic crust during proterozoic orogenies |
| topic | Archean oceanic crust Proterozoic orogens Borborema province |
| url | http://www.sciencedirect.com/science/article/pii/S1674987120300633 |
| work_keys_str_mv | AT alanielsondacamaradantasferreira highpressuremetamorphicrocksintheborboremaprovincenortheastbrazilreworkingofarcheanoceaniccrustduringproterozoicorogenies AT eltonluizdantas highpressuremetamorphicrocksintheborboremaprovincenortheastbrazilreworkingofarcheanoceaniccrustduringproterozoicorogenies AT ticianojosesaraivadossantos highpressuremetamorphicrocksintheborboremaprovincenortheastbrazilreworkingofarcheanoceaniccrustduringproterozoicorogenies AT reinhardtafuck highpressuremetamorphicrocksintheborboremaprovincenortheastbrazilreworkingofarcheanoceaniccrustduringproterozoicorogenies AT mahyratedeschi highpressuremetamorphicrocksintheborboremaprovincenortheastbrazilreworkingofarcheanoceaniccrustduringproterozoicorogenies |