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The Limoeiro Deposit: Ni-Cu-PGE Sulfide Mineralization Hosted Within an Ultramafic Tubular Magma Conduit in the Borborema Province, Northeastern Brazil

2013; Volume: 108; Issue: 7 Linguagem: Inglês

10.2113/econgeo.108.7.1753

1554-0774

Jonas Mota-E-Silva, César Fonseca Ferreira Filho, Maria Emília Schutesky,

Mineralogy and Gemology Studies

Research Article| November 01, 2013 The Limoeiro Deposit: Ni-Cu-PGE Sulfide Mineralization Hosted Within an Ultramafic Tubular Magma Conduit in the Borborema Province, Northeastern Brazil Jonas Mota-e-Silva; Jonas Mota-e-Silva † 1Votorantim Metais Ltda., Praça Ramos de Azevedo, 254, São Paulo, SP. 01037-912, Brazil2Instituto de Geociências, Universidade de Brasília, Brasília, DF. 70910-900, Brazil †Corresponding author: email, jonas.silva@vmetais.com.br Search for other works by this author on: GSW Google Scholar Cesar Fonseca Ferreira Filho; Cesar Fonseca Ferreira Filho 2Instituto de Geociências, Universidade de Brasília, Brasília, DF. 70910-900, Brazil Search for other works by this author on: GSW Google Scholar Maria Emilia Schutesky Della Giustina Maria Emilia Schutesky Della Giustina 2Instituto de Geociências, Universidade de Brasília, Brasília, DF. 70910-900, Brazil Search for other works by this author on: GSW Google Scholar Author and Article Information Jonas Mota-e-Silva † 1Votorantim Metais Ltda., Praça Ramos de Azevedo, 254, São Paulo, SP. 01037-912, Brazil2Instituto de Geociências, Universidade de Brasília, Brasília, DF. 70910-900, Brazil Cesar Fonseca Ferreira Filho 2Instituto de Geociências, Universidade de Brasília, Brasília, DF. 70910-900, Brazil Maria Emilia Schutesky Della Giustina 2Instituto de Geociências, Universidade de Brasília, Brasília, DF. 70910-900, Brazil †Corresponding author: email, jonas.silva@vmetais.com.br Publisher: Society of Economic Geologists Received: 02 Nov 2012 Accepted: 26 Mar 2013 First Online: 01 Mar 2017 Online ISSN: 1554-0774 Print ISSN: 0361-0128 © 2013 Society of Economic Geologists. Economic Geology (2013) 108 (7): 1753–1771. https://doi.org/10.2113/econgeo.108.7.1753 Article history Received: 02 Nov 2012 Accepted: 26 Mar 2013 First Online: 01 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Jonas Mota-e-Silva, Cesar Fonseca Ferreira Filho, Maria Emilia Schutesky Della Giustina; The Limoeiro Deposit: Ni-Cu-PGE Sulfide Mineralization Hosted Within an Ultramafic Tubular Magma Conduit in the Borborema Province, Northeastern Brazil. Economic Geology 2013;; 108 (7): 1753–1771. doi: https://doi.org/10.2113/econgeo.108.7.1753 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyEconomic Geology Search Advanced Search Abstract The Limoeiro deposit, located in a high-grade mobile belt of the Brasiliano orogenic cycle (650–500 Ma), represents one of the few magmatic Ni-Cu(-PGE) sulfide discoveries in recent years. The deposit is hosted by an ultramafic chonolith consisting in a partly deformed and metamorphosed tube-like body affected by brittle faults within high-grade gneiss and schist. The absolute age of the ultramafic intrusion that hosts the Limoeiro deposit is not yet known, but regional geologic constraints suggest that both intrusion and host rocks belong to a terrane older than the orogenic cycle. Peak metamorphic parageneses of the ultramafic intrusion and country rocks indicate granulite facies of metamorphism, interpreted as the result of the Neoproterozoic Brasiliano orogenic cycle. The Limoeiro deposit is the first significant discovery of Ni-Cu sulfide in the Borborema province, opening a new window for exploration in this large orogenic belt.Despite the high-grade metamorphism and the tectonic deformation, the primary magmatic structure of the intrusion hosting the Limoeiro deposit is remarkably well preserved. This intrusion forms a tube-like conduit (chonolith) with cross sections a few hundreds of meters in diameter and with a considerable length of more than 4 km. The conduit consists of two distinct sequences of ultramafic rocks, denominated Upper and Lower sequences, each one consisting of a core of harzburgite enveloped by orthopyroxenite, with an irregular and discontinuous outer shell of amphibolite. These ultramafic sequences, characterized by similar composition and structure, have distinctively different S contents resulting from the presence of disseminated Ni-Cu sulfide mineralization only in the Upper sequence. The magmatic system of the Limoeiro deposit is interpreted to result from the input of two major pulses of magma with similar composition, but sulfide saturation and segregation is restricted to the second magma pulse (Upper sequence). Nickel-Cu(-PGE) sulfide mineralization is broadly concordant with the Upper sequence and different orebodies resulted from tectonic slicing of the originally continuous tube-like structure. The bulk of the mineralization in all orebodies consists of thick (up to 150 m) and elongated (up to 1 km) masses of rock containing disseminated sulfides broadly concordant with the chonolithic structure. Thin layers of massive ore occur in the lower portions of some of the orebodies, and represent about 3 vol % of the Limoeiro deposit. The intrusion hosting the Limoeiro deposit is probably the best preserved chonolith that has been overprinted by granulite facies metamorphism within an orogenic terrane. This study indicates that reconstruction of small magma conduits, an important tool for exploration for Ni-Cu sulfide deposits, may be successfully achieved within high-grade orogenic terranes. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.