Controle estrutural dos pegmatitos ricos em etr associados ao depósito madeira (Sn-nb-ta), mina pitinga, amazonas, brasil.

Publikation: Beitrag in Fachzeitschrift › Artikel › Forschung › Peer-Review

Autorschaft

  • Fernanda Claas Ronchi
  • Fernando Jacques Althoff
  • Artur Cezar Bastos Neto
  • Harald G. Dill

Organisationseinheiten

Externe Organisationen

  • Universidade Federal do Rio Grande do Sul
  • Universidade Federal de Santa Catarina
  • Universidade La Salle
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Details

Titel in ÜbersetzungStructural control of REE-pegmatites associated with the world-class Sn-Nb-Ta-cryolite deposit at the pitinga mine, amazonas, brazil
OriginalsprachePortugiesisch
Aufsatznummere0734
Seitenumfang14
FachzeitschriftPesquisas em Geociencias
Jahrgang46
Ausgabenummer1
PublikationsstatusVeröffentlicht - 7 Juni 2019

Abstract

Estudou-se o controle estrutural dos veios de pegmatitos graníticos (tipo F-ETR-Li) associados à fácies albita granito (AEG) do granito Madeira (~1.83Ga). Esta fácies corresponde ao depósito, de classe mundial de Sn-NbTa-F (criolita) da mina de Pitinga. Atualmente, esses pegmatitos ricos em ETR [xenotima-(Y) e gagarinita-(Y)] são explorados junto com o minério disseminado, porém possuem potencial para exploração por lavra seletiva. Todos os pegmatitos se enquadram em um mesmo arranjo geométrico e apresentam uma mesma mineralogia, o que sugere que se originaram de uma mesma fonte. Sua mineralogia é igual à da encaixante, o que sugere que seu alojamento ocorreu na própria rocha parental. O arranjo geométrico dos pegmatitos é determinado por estruturas contracionais frágeis (falhas inversas, leques imbricados e cavalos). Os planos de falhas inversas (N320/60SW) serviram como condutos para o fluido que se alojou preferencialmente em fraturas horizontais distensivas. O arranjo geométrico bem definido dessas estruturas e o fato de que também há planos de falhas inversas sem pegmatitos sugerem que as fraturas que hospedam os pegmatitos não foram geradas pela pressão do fluido. A orientação das estruturas contracionais no AEG indica que ocorreu um transporte de SW para NE. Como este corpo possui pequena dimensão, resfriou-se rapidamente. Contudo, sua localização na crosta superior fria e a baixa temperatura do solidus permitiram a formação dos pegmatitos. Os pegmatitos foram formados com o AEG colocado em um nível estrutural acima da profundidade crustal crítica, onde a tensão mínima normal é vertical.

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Controle estrutural dos pegmatitos ricos em etr associados ao depósito madeira (Sn-nb-ta), mina pitinga, amazonas, brasil. / Ronchi, Fernanda Claas; Althoff, Fernando Jacques; Bastos Neto, Artur Cezar et al.
in: Pesquisas em Geociencias, Jahrgang 46, Nr. 1, e0734, 07.06.2019.

Publikation: Beitrag in Fachzeitschrift › Artikel › Forschung › Peer-Review

Ronchi, FC, Althoff, FJ, Bastos Neto, AC & Dill, HG 2019, 'Controle estrutural dos pegmatitos ricos em etr associados ao depósito madeira (Sn-nb-ta), mina pitinga, amazonas, brasil.', Pesquisas em Geociencias, Jg. 46, Nr. 1, e0734. https://doi.org/10.22456/1807-9806.93249
Ronchi, F. C., Althoff, F. J., Bastos Neto, A. C., & Dill, H. G. (2019). Controle estrutural dos pegmatitos ricos em etr associados ao depósito madeira (Sn-nb-ta), mina pitinga, amazonas, brasil. Pesquisas em Geociencias, 46(1), Artikel e0734. https://doi.org/10.22456/1807-9806.93249
Ronchi FC, Althoff FJ, Bastos Neto AC, Dill HG. Controle estrutural dos pegmatitos ricos em etr associados ao depósito madeira (Sn-nb-ta), mina pitinga, amazonas, brasil. Pesquisas em Geociencias. 2019 Jun 7;46(1):e0734. doi: 10.22456/1807-9806.93249
Ronchi, Fernanda Claas ; Althoff, Fernando Jacques ; Bastos Neto, Artur Cezar et al. / Controle estrutural dos pegmatitos ricos em etr associados ao depósito madeira (Sn-nb-ta), mina pitinga, amazonas, brasil. in: Pesquisas em Geociencias. 2019 ; Jahrgang 46, Nr. 1.
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title = "Controle estrutural dos pegmatitos ricos em etr associados ao dep{\'o}sito madeira (Sn-nb-ta), mina pitinga, amazonas, brasil.",
abstract = "We have studied the structural control of pegmatites (F-REE-Li vein-type granite pegmatite) associated with the albite-enriched granite facies (AEG) of the Madeira A-type granite (~1.83 Ga). This facies corresponds to the Madeira world-class Sn-Nb-Ta-F (cryolite) deposit at the Pitinga mine. These REE-rich pegmatites [xenotime-(Y) and gagarinite-(Y)], presently exploited together with the disseminated ore, have potential to exploitation by selective mining. They have a common geometric arrangement and share the same mineralogy, therefore they all originated from the same source. They have the same mineralogical composition of the host rock and their emplacement occurred in the parental rock itself. The geometric arrangement of the pegmatites is settled by contractional brittle structures (reverse faults, imbrication fans and horses). The reverse fault planes (~N320/60SW) were essentially the conduits for the fluid. The preferential sites for the pegmatites bodies were horizontal tensile fractures. The well-marked geometric arrangement of the tectonic structures and the fact that there are also reverse faults planes without pegmatites show that the fractures that host the pegmatites were not formed by the fluid pressure. The orientation of the contractional structures in the AEG indicates a transport from SW to NE. With reduced dimensions, the AEG cooled fast, however its location in the cold upper crust and the low solidus temperature allowed pegmatites formation. The pegmatites were formed with the AEG emplaced in a structural level above the critical crustal depth, where minimum normal stress is vertical.",
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author = "Ronchi, {Fernanda Claas} and Althoff, {Fernando Jacques} and {Bastos Neto}, {Artur Cezar} and Dill, {Harald G.}",
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T1 - Controle estrutural dos pegmatitos ricos em etr associados ao depósito madeira (Sn-nb-ta), mina pitinga, amazonas, brasil.

AU - Ronchi, Fernanda Claas

AU - Althoff, Fernando Jacques

AU - Bastos Neto, Artur Cezar

AU - Dill, Harald G.

N1 - Publisher Copyright: © 2019, Universidade Federal do Rio Grande do Sul. All rights reserved.

PY - 2019/6/7

Y1 - 2019/6/7

N2 - We have studied the structural control of pegmatites (F-REE-Li vein-type granite pegmatite) associated with the albite-enriched granite facies (AEG) of the Madeira A-type granite (~1.83 Ga). This facies corresponds to the Madeira world-class Sn-Nb-Ta-F (cryolite) deposit at the Pitinga mine. These REE-rich pegmatites [xenotime-(Y) and gagarinite-(Y)], presently exploited together with the disseminated ore, have potential to exploitation by selective mining. They have a common geometric arrangement and share the same mineralogy, therefore they all originated from the same source. They have the same mineralogical composition of the host rock and their emplacement occurred in the parental rock itself. The geometric arrangement of the pegmatites is settled by contractional brittle structures (reverse faults, imbrication fans and horses). The reverse fault planes (~N320/60SW) were essentially the conduits for the fluid. The preferential sites for the pegmatites bodies were horizontal tensile fractures. The well-marked geometric arrangement of the tectonic structures and the fact that there are also reverse faults planes without pegmatites show that the fractures that host the pegmatites were not formed by the fluid pressure. The orientation of the contractional structures in the AEG indicates a transport from SW to NE. With reduced dimensions, the AEG cooled fast, however its location in the cold upper crust and the low solidus temperature allowed pegmatites formation. The pegmatites were formed with the AEG emplaced in a structural level above the critical crustal depth, where minimum normal stress is vertical.

AB - We have studied the structural control of pegmatites (F-REE-Li vein-type granite pegmatite) associated with the albite-enriched granite facies (AEG) of the Madeira A-type granite (~1.83 Ga). This facies corresponds to the Madeira world-class Sn-Nb-Ta-F (cryolite) deposit at the Pitinga mine. These REE-rich pegmatites [xenotime-(Y) and gagarinite-(Y)], presently exploited together with the disseminated ore, have potential to exploitation by selective mining. They have a common geometric arrangement and share the same mineralogy, therefore they all originated from the same source. They have the same mineralogical composition of the host rock and their emplacement occurred in the parental rock itself. The geometric arrangement of the pegmatites is settled by contractional brittle structures (reverse faults, imbrication fans and horses). The reverse fault planes (~N320/60SW) were essentially the conduits for the fluid. The preferential sites for the pegmatites bodies were horizontal tensile fractures. The well-marked geometric arrangement of the tectonic structures and the fact that there are also reverse faults planes without pegmatites show that the fractures that host the pegmatites were not formed by the fluid pressure. The orientation of the contractional structures in the AEG indicates a transport from SW to NE. With reduced dimensions, the AEG cooled fast, however its location in the cold upper crust and the low solidus temperature allowed pegmatites formation. The pegmatites were formed with the AEG emplaced in a structural level above the critical crustal depth, where minimum normal stress is vertical.

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KW - Amazonas

KW - Pegmatite

KW - Pitinga mine

KW - Rare earth elements

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JO - Pesquisas em Geociencias

JF - Pesquisas em Geociencias

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