An intrusion-related origin for Cu–Au mineralization in iron oxide–copper–gold (IOCG) provinces

Pollard, P. J.

doi:10.1007/s00126-006-0054-x

Cited by 169 publications

(61 citation statements)

References 47 publications

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“…Plausible hypotheses to explain the data include a magmatic origin either by purely magmatic processes, such as liquid immiscibility that is thought to have formed Fe-Ti-P/V deposits in layered intrusions such as the Bushveld Complex, South Africa (VanTongeren and Mathez, 2012) and Sept Iles layered intrusion, Canada (Charlier et al, 2011), or by magmatichydrothermal processes similar to those that form porphyry copper deposits (e.g., Baker, 2002;Candela and Piccoli, 2005;Pollard et al 2006).…”

Section: Identification Of the Magnetites Origin At Los Coloradosmentioning

confidence: 99%

Trace elements in magnetite from massive iron oxide-apatite deposits indicate a combined formation by igneous and magmatic-hydrothermal processes

Knipping

Bilenker

Simon

et al. 2015

Geochimica et Cosmochimica Acta

217

104

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This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. data demonstrate that a saline magmatic-hydrothermal ore fluid will scavenge significant quantities of metals such as Cu and Au from a silicate melt, and when combined with solubility data for Fe, Cu and Au, it is plausible that the magmatic-hydrothermal ore fluid that continues to ascend from the IOA depositional environment can retain sufficient concentrations of these metals to form iron oxide copper-gold (IOCG) deposits at lateral and/or stratigraphically higher levels in the crust. Notably, this study provides a new discrimination diagram to identify magnetite from Kiruna-type deposits and to distinguish them from IOCG, porphyry and Fe-Ti-V/P deposits, based on low Cr (< 100 ppm) and high V (>500 ppm) concentrations. Trace elements in magnetite from massive iron oxide-apatite deposits indicate a combined formation by igneous and magmatic-hydrothermal processes

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Section: Identification Of the Magnetites Origin At Los Coloradosmentioning

confidence: 99%

Trace elements in magnetite from massive iron oxide-apatite deposits indicate a combined formation by igneous and magmatic-hydrothermal processes

Knipping

Bilenker

Simon

et al. 2015

Geochimica et Cosmochimica Acta

217

104

View full text Add to dashboard Cite

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“…The stable isotope character (  O,   S, and δ 37 Cl) of IOCG mineralizing fluids has been used to suggest that they originated as magmatic, evaporitic, formation, metamorphic, and seawater derived, or as mixtures of some of these end-members (e.g., Oreskes and Einaudi, 1992;Williams, 1994;Pollard, 2000Pollard, , 2006Chiaradia et al, 2006;Benavides et al, 2007;Hunt et al, 2007;de Haller and Fontboté, 2009;Gleeson and Smith, 2009). The presence of apparently evaporite-derived fluids in some deposits has been postulated as a key factor for the development of the extensive Ca and Na alteration and complexation of metals in some IOA and IOCG systems (Barton andJohnson, 1996, 2000;Baker et al, 2008;Xavier et al, 2008;Gleeson and Smith, 2009;Barton, 2014).…”

Section: Iocg and Ioa Depositsmentioning

confidence: 99%

“…Halogen and noble gas studies from selected IOCGs and IOAs have reinforced the presence of non-magmatic fluid sources in the mineralizing system and the importance of magmatic-derived fluids mixing with non-magmatic fluids, for metal deposition (Chiaradia et al, 2006;Fisher and Kendrick, 2008;Smith et al, 2012). Alternatively, a number of investigators suggest that the alteration and ore minerals in IOCG systems have a magmatic, or dominantly magmatic source, derived from calc-alkaline to moderately alkaline suites similar to the ones responsible for Cu-Au porphyry deposits (Pollard, 2000(Pollard, , 2006Mumin et al, 2010;Richards and Mumin, 2013a,b). Pollard (2001) further suggests that high levels of CO 2 promote the separation of ore fluids from the crystallizing magma at a wide range of pressures that are compatible with the depths inferred for these systems.…”

Section: Iocg and Ioa Depositsmentioning

confidence: 99%

A Paleoproterozoic Andean-type iron oxide copper-gold environment, the Great Bear magmatic zone, Northwest Canada

Ootes

Snyder

Davis

et al. 2017

Ore Geology Reviews

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Iron oxide copper-gold (IOCG) and associated iron-oxide apatite (IOA) styles of metallic mineralization are recognized throughout the Paleoproterozoic Great Bear magmatic zone of the northwest Canadian Shield. The Great Bear magmatic zone was constructed between ca. 1876 and 1855 Ma on top of the older Hottah terrane, which preserves continental arc magmatism that began around ca. 2.0 to 1.97 Ga and continued between ca. 1.93 and 1.89 Ga. The Great Bear represents the final stages of ca. 150 million years of intermittent and pulsed magmatism related to an evolving continental orogenic belt. The preserved geology supports a dramatic geodynamic change in the subduction zone process at ca. 1875 Ma, a key driving mechanism for magma and metal mobilization, and was rapidly followed by a large-scale introduction of felsic-intermediate plutons. The overall tectonic setting is partially constrained from new and previously published geochemical data that show that the volcanic and plutonic rocks are high-K calc-alkaline to shoshonitic in nature (e.g., high K 2 O, Th/Yb, and Ce/P 2 0 5 ). They also have suprasubduction-zone geochemical signatures, including primitive mantle normalized positive Th and negative Nb, P, and Ti anomalies. The data support the primary melts were derived from a GLOSS-modified mantle wedge. Three-dimensional rendering of geophysical datasets suggest that two (of four) preserved surfaces within the upper mantle lithosphere, at 70 to 120 km depths, represent frozen, subducted oceanic slabs, and likely were the drivers for the bulk of Hottah and Great Bear arc magmatism. The older slab is northwest-striking and dips 12⁰ to 15⁰ northeast, whereas the younger is deeper and north-striking, dipping 13⁰ east. The geometry of the surfaces are comparable with 4D modeling, where a subduction zone is temporarily shut down due to plateau collision, and then steps oceanward and re-initiates; there is no need for polarity reversal of the subduction system. This new geometry and the related inferences about process should be the focus of future research in the region, but for the time-being it can be stated that these subduction and collisional processes were the first order control on lithospheric evolution, and therefore metallic mineralization. Overall, the Great Bear magmatic zone IOCG and related mineralization is not comparable to other Proterozoic IOCG belts, such as those in Australia. However, the complexity of mineralization styles, the spatial-temporal relationship between IOA and IOCG mineralization, the suprasubduction zone environment, and a major change in tectonic regime are features similar to Andean-type IOCG mineralization, as well as Cordilleran alkali porphyry Cu-A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT3 Au deposits. This further establishes the linkages between subduction zone processes and IOCG formation, as well as relationships in the IOCG-porphyry deposit continuum model.

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“…Factors influencing the formation of unconformity related deposits are the hot, oxidized, Ca-rich brine which dissolved uranium bearing minerals and void space created by reverse tectonics and quartz dissolution (Cuney, 2009 (Pollard, 2006). Uranium precipitation occurred when hot, saline brines from felsic magma mixed with oxidized, meteoric water.…”

Section: Overview Of Uranium Depositsmentioning

confidence: 99%

Residence of Uranium in Roll-Front Deposits: A Case Study

Wyatt¹

2016

Geological Society of America Abstracts With Programs

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Despite generally low uranium grades, roll-front uranium deposits are attractive exploration targets as these deposits are amenable to in-situ leaching (ISL) techniques. At the Lost Creek Project, a currently operating uranium mine in Wyoming, head grades were five times higher than pre-operational estimates. Similar mines, such as the Crow Butte mine in Nebraska, have experienced head grades that are in good agreement with pre-operational estimates. Ore samples from the Lost Creek Project and the Three Crow Expansion Area, a satellite deposit to the Crow Butte mine, were analyzed in order to understand their mineralogy and to understand the discrepancy between head grades and pre-operational estimates at the Lost Creek Project.Fission track mapping, quantitative trace element mapping of selected areas using EPMA and high-resolution BSE imaging revealed that the uranium phases at the Lost Creek Project are contained in small (<1 µm) wispy phases. Using SEM and TEM techniques, the U bearing phases were identified as a fine intergrowth of kaolinite with becquerelite (Ca(UO2)6O4(OH)6·8(H2O)) and uranophane (Ca(H3O)2(UO2)2(SiO4)2·3H2O). Initial head grades at Lost Creek of 211 ppm are in good agreement with solubility experiments for highly soluble becquerelite (250 ppm), whereas uranophane solubility peaks at 75 ppm in a bicarbonate concentration of 2.0x10 -2 mol/L, which is in good agreement with bicarbonate concentrations used at the Lost Creek Project and with current head grades of 42 ppm. The large discrepancy of estimates and initial head grades at the Lost Creek Project is partly due to the different gamma ray intensity of uranophane versus primary U ore minerals usually found in U roll-front deposits.Uranophane has a gamma ray response of almost half of both uraninite and coffinite leading to an underestimated resource estimate. Moreover, the mobile nature of the U 6+ ion allowed uranium mineralization of secondary minerals to occur away from the primary ore zone leading to a less well defined, larger ore zone.Ore mineralogy at the Three Crow Expansion area was identified to be primarily coffinite (U(SiO4)1−x(OH)4x) and is in good agreement with previous work and the ore mineralogy at the Crow Butte mine. In contrast, the Lost Creek Project is highly oxidized and primary U ore minerals have been replaced by secondary becquerelite and uranophane.iv

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An intrusion-related origin for Cu–Au mineralization in iron oxide–copper–gold (IOCG) provinces

Cited by 169 publications

References 47 publications

Trace elements in magnetite from massive iron oxide-apatite deposits indicate a combined formation by igneous and magmatic-hydrothermal processes

Trace elements in magnetite from massive iron oxide-apatite deposits indicate a combined formation by igneous and magmatic-hydrothermal processes

A Paleoproterozoic Andean-type iron oxide copper-gold environment, the Great Bear magmatic zone, Northwest Canada

Residence of Uranium in Roll-Front Deposits: A Case Study

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