The Fractal Nature of Structural Controls on Ore Formation: The Case of the Iron Oxide Copper-Gold Deposits in the Carajás Mineral Province, Brazilian Amazon

2018 ◽  
Vol 113 (7) ◽  
pp. 1499-1524 ◽  
Author(s):  
Paulo Miguel Haddad-Martim ◽  
Emmanuel John M. Carranza ◽  
Carlos Roberto de Souza Filho
Keyword(s):  
Iron Oxide ◽  
Brazilian Amazon ◽  
Gold Deposits ◽  
Fractal Nature ◽  
Ore Formation ◽  
Structural Controls ◽  
Carajás Mineral Province ◽  
Copper Gold

Stable isotopes and fluid inclusion constraints on the fluid evolution in the Bacaba and Castanha iron oxide-copper-gold deposits, Carajás Mineral Province, Brazil

2020 ◽  
Vol 126 ◽  
pp. 103738 ◽  
Author(s):  
André Luiz Silva Pestilho ◽  
Lena Virgínia Soares Monteiro ◽  
Gustavo Henrique Coelho de Melo ◽  
Carolina PenteadoNatividade Moreto ◽  
Caetano Juliani ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Iron Oxide ◽  
Fluid Inclusion ◽  
Gold Deposits ◽  
Carajás Mineral Province ◽  
Fluid Evolution ◽  
Copper Gold

Application of 3D magnetic amplitude inversion to iron oxide-copper-gold deposits at low magnetic latitudes: A case study from Carajás Mineral Province, Brazil

Geophysics ◽  
2015 ◽  
Vol 80 (2) ◽  
pp. B13-B22 ◽  
Author(s):  
Marcelo Leão-Santos ◽  
Yaoguo Li ◽  
Roberto Moraes
Keyword(s):  
Iron Oxide ◽  
Gold Deposits ◽  
Magnetic Data ◽  
Magnetic Latitude ◽  
Amplitude Inversion ◽  
Carajás Mineral Province ◽  
Amplitude Data ◽  
Copper Gold ◽  
Magnetic Amplitude

Strong hydrothermal alteration modifies rock physical properties in iron oxide-copper-gold deposits (IOCGs) and may result in characteristic signatures detectable in geophysical surveys. Magnetic data are commonly used in characterizing orebodies, and 3D inversions are often used to assist in interpretations. In areas with strong remanence and self-demagnetization, the total magnetization can have directions different from the inducing field direction. This deviation precludes the use of traditional inversion methods. Magnetic amplitude inversion offers one solution to this challenge because the amplitude data are weakly dependent on the magnetization direction. In addition, the low magnetic latitude also imposes difficulty in amplitude data calculation due to the instability in the component conversion in the wavenumber domain. To formulate a practical approach, we present a case study on applying the magnetic amplitude inversion to the Furnas southeast IOCG deposit at the low magnetic latitude in Carajás Mineral Province, Brazil, and demonstrate that the approach can reliably recover an interpretable distribution of effective magnetic susceptibility and identify massive magnetite from hydrothermal alterations associated with the high-grade ore.

Magnetic modeling of iron oxide copper-gold mineralization constrained by 3D multiscale integration of petrophysical and geochemical data: Cloncurry District, Australia

2013 ◽  
Vol 1 (1) ◽  
pp. T63-T84 ◽  
Author(s):  
James R. Austin ◽  
Phillip W. Schmidt ◽  
Clive A. Foss
Keyword(s):  
Iron Oxide ◽  
Gold Mineralization ◽  
Signal Amplitude ◽  
Gold Deposits ◽  
Geochemical Data ◽  
Geophysical Investigation ◽  
Structural Controls ◽  
Breccia Pipe ◽  
Copper Gold

Magnetite-rich iron oxide copper-gold deposits (IOCGs) are geologically and geochemically complex and present major challenges to geophysical investigation. They often sit beneath significant cover, exhibit magnetic remanence, and suffer from self-demagnetization effects. Because remanence in magnetite-bearing drill core samples is commonly overprinted by drilling, in situ natural remanent magnetization is difficult to measure accurately, and thus IOCGs cannot be modeled definitively using geophysics alone. We examined structural controls on a magnetite-rich IOCG in northwest Queensland and the relationships between structure, alteration, Fe oxides, and mineralization at core to deposit scale. Magnetite within the deposit has a multidomain structure, and thus it would commonly have an in situ magnetization parallel to the earth’s field. In contrast, pyrrhotite has a pseudosingle-domain structure and so it is the predominant carrier of stable remanence within the ore system. Geophysical lineament analyses are used to determine structural controls on mineralization, geophysical filters (e.g., analytic signal amplitude) are used to help define structural extent of the deposit, and basement geochemistry is used to map mineral footprints beneath cover. These techniques identified coincident anomalies at the intersection of north and northwest lineaments. Leapfrog™ interpolations of downhole magnetic susceptibility and Cu, Au, and Fe assay data were used to map the distribution of magnetite, copper, gold, and sulfur in 3D. The analysis revealed that Cu and Au mineralization were coupled with the magnetite net-vein architecture, but that Cu was locally enriched in the east–northeast-trending demagnetized zone. The results from this suite of geophysical, petrophysical, and geochemical techniques were integrated to constrain modeling of the Brumby IOCG. Brumby can be described as a breccia pipe sitting at the intersection of north-striking, east-dipping, and northwest-striking, southeast-dipping structures that plunges moderately to the south–southeast. The breccia pipe was overprinted by a relatively late net-vein magnetite breccia and crosscut by a later, magnetite-destructive, east–northeast-striking fault.

Tourmaline B-isotopes fingerprint marine evaporites as the source of high-salinity ore fluids in iron oxide copper-gold deposits, Carajás Mineral Province (Brazil)

Geology ◽  
2008 ◽  
Vol 36 (9) ◽  
pp. 743 ◽  
Author(s):  
Roberto Perez Xavier ◽  
Michael Wiedenbeck ◽  
Robert B. Trumbull ◽  
Ana M. Dreher ◽  
Lena V.S. Monteiro ◽  
...  
Keyword(s):  
Iron Oxide ◽  
High Salinity ◽  
Gold Deposits ◽  
Carajás Mineral Province ◽  
Copper Gold

Very rapid subsurface hydrothermal ore deposition mechanisms and the origin of breccia-hosted iron-oxide copper–gold deposits

2009 ◽  
Vol 101 (1) ◽  
pp. 76 ◽  
Author(s):  
Nicholas H.S. Oliver ◽  
Michael J. Rubenach ◽  
Jaiby-Ann Jacob ◽  
Brian G. Rusk ◽  
Martina Bertelli ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Gold Deposits ◽  
Copper Gold ◽  
Ore Deposition
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