James E Mungall

James E Mungall
Carleton University · Department of Earth Sciences

PhD

About

127
Publications
21,218
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Introduction
We use a combination of field work and numerical or thermodynamic modeling to address basic questions in igneous petrology. We have a principal focus on the behaviour of the platinum group elements (PGE) and sulfide liquids in the genesis of magmatic ore deposits and in the genesis of magmas in general. Current topics of interest include the origins of layering in mafic intrusive complexes and the distribution of chalcophile elements in the Earth's mantle and crust.
Additional affiliations
January 1999 - present
University of Toronto
Position
  • Professor (Associate)
Education
September 1987 - November 1993
McGill University
Field of study
  • Geology

Publications

Publications (127)
Article
The highest grade Pd-Pt deposit on Earth, the J-M Reef, is hosted in coarse-grained to pegmatoidal cumulates called the Reef Package. Decades of mine development of the J-M Reef have revealed that a distinct discontinuity in rock fabric marks the top of the rock unit that hosts economic grade sulfide mineralization. Mine geologists refer to this di...
Article
A 3D geological model of the Archean Esker ultramafic-mafic intrusive complex of the Ring of Fire intrusive suite of northwestern Ontario (Canada) is presented, providing insight into the nature of its magmatic plumbing system and allowing for speculation on the formation of its valuable Ni-Cu-(PGE) and chromitite deposits. The 3D model was constra...
Article
The komatiitic Raglan Horizon in northern Quebec hosts one of the largest komatiite-associated magmatic sulfide deposits in the world. Several studies have suggested that the sulfide ores were formed by melting and transporting sedimentary sulfides from upstream after the komatiite melt had assimilated a large amount of S-rich country rocks. In thi...
Article
Magmatic sulfide deposits are generated by extraordinary accumulations of immiscible sulfide liquids in ultramafic-mafic magmas. While their associated geochemical and petrogenetic systems are well understood, the fluid dynamic processes that control the formations of ore bodies and textures are much less well known, particularly during lateral mag...
Article
Full-text available
The great economic significance of layered mafic-ultramafic intrusions like the Bushveld Complex of South Africa results from the existence within them of some layers highly concentrated in valuable elements. Here we address the origins of the Main Magnetite Layer, a globally important resource of Fe-Ti-V-rich magnetite. Previous models of in situ...
Article
Full-text available
The origin and parental magma for layered cumulates in the Lower Banded series (LBS) and the J-M Reef Pd-Pt deposit of the Stillwater Complex remains poorly constrained. We present whole-rock lithogeochemistry and mineral chemistry from LBS rocks collected from drill holes and surface samples from the Mountain View area of the complex that in total...
Article
Full-text available
The platinum-group element (PGE) contents of komatiites have been used to estimate the PGE contents of their mantle sources and investigate temporal variations in the PGE systematics of the mantle throughout Earth history. However, the use of mantle melts to investigate source characteristics is critically dependent on understanding the fractionati...
Article
The Brazilian Pilar and Três Buracos gold deposits are Paleoproterozoic mid-tier deposits located in the southwestern Pilar de Goiás greenstone belt, containing 61,688 kg and 7,144 kg of gold, respectively, in addition to approximately 30,000 kg of past production (1736-2018). This research aimed to assess the hypothesis that the mobility of alkali...
Preprint
Full-text available
The great economic significance of layered mafic-ultramafic intrusions like the Bushveld Complex of South Africa results from the existence within them of some layers highly concentrated in valuable elements. Here we address the origins of the Main Magnetite Layer, a globally important resource of Fe-Ti-V-rich magnetite. Previous models of in situ...
Article
Genesis of magmatic Ni-Cu-(PGE) deposits involves many interconnected and multiple-scale processes in the fields of thermodynamics, kinetics and fluid dynamics. The main focus of quantitative work on magmatic sulfide ore genesis has been on equilibrium thermodynamics since the initial studies over 50 years ago, while the significance of kinetics an...
Article
Full-text available
The world-class magmatic sulfide deposits in the Norilsk region exhibit a remarkable spatial and temporal association with the Siberian large igneous province (LIP). However, the details of the causal connection between the Siberian LIP and the ore deposits have remained contentious. Here we address the problem by modeling of assimilation, crystall...
Article
Full-text available
The Rustenburg Layered Suite of the Bushveld Complex of South Africa is a vast layered accumulation of mafic and ultramafic rocks. It has long been regarded as a textbook result of fractional crystallization from a melt-dominated magma chamber. Here, we show that most units of the Rustenburg Layered Suite can be derived with thermodynamic models of...
Article
In this contribution, we analyze 30 years of mine development data and quantitatively identify the processes that control the grade and tenor of the mineralized rock. An assay database of more than 60,000 samples was used to examine variations in ore grade and tenor of the sulfide mineralization in the J-M reef horizon of the Stillwater Complex alo...
Article
There has been vigorous debate for several decades about whether the extreme enrichments of platinum group elements (PGEs) in some magmatic sulfide deposits could have resulted from simple equilibration of sulfide liquid with silicate melt. Key examples include the Ni-Cu-Pd mineralization in the Norilsk mining camp, the UG2 and Merensky reef Pt-Pd...
Preprint
Full-text available
The Rustenburg Layered Suite (RLS) of the Bushveld Complex of South Africa is a vast layered accumulation of mafic and ultramafic rocks. The layers are widely assumed to result from fractional crystallization from a melt-dominated magma chamber. We derive compositions of all units of the RLS with thermodynamic models of assimilation of crust by a k...
Article
The motion of dense Fe-rich immiscible sulphide liquids is generally supposed to be dominated by gravitational settling in crustal magma chambers, however they may become buoyant by attachment to low-density vapour bubbles to form compound drops, possibly contributing to the upward transfer of sulphur and transition metals in degassing magma bodies...
Article
The Superior craton is bordered on its northern and eastern sides by the approximately coeval Cape Smith fold belt and the Labrador Trough, two major Paleoproterozoic volcano-sedimentary belts that record broadly similar tectonic evolution but which show some distinctive characteristics and have notably different mineral resource endowments. The Ro...
Article
High pressure phase relations for much of the Cu-Fe-S system have not previously been determined experimentally. Experimental studies have concentrated on low-pressure phase relations and cannot explain high pressure sulfide mineral inclusion assemblages in some natural blueschists and eclogites. In particular, the co-existence of pyrite + covellit...
Article
Conventional models of the genesis of the Rustenburg Layered Suite (RLS) of the Bushveld Complex postulate that it is the product of a single multiply-replenished magma chamber that cooled as a single massive unit, i.e., a monolithic magma chamber. This concept has been challenged by alternative hypotheses involving out-of-sequence emplacement of s...
Article
A close relationship between Ni-Cu-PGE sulfide deposits and magmatic conduit systems has been widely accepted, but our present understanding still rests on empirical inductions that sulfide liquids are entrained during magma ascent and aggregated at hydrodynamic traps such as the opening of a conduit into a larger magma body. In this contribution,...
Article
Full-text available
The Moon accreted meteoritic material towards the end of Solar System formation. Quantification of this late accretion requires an estimation of the abundance of highly siderophile, or iron-loving, elements in the lunar mantle. As lunar mantle samples are not available, estimates are derived from lunar basalt compositions, but the melting phase rel...
Article
Full-text available
Here, we critically examine models for the development of layering in the ultramafic rocks of the Stillwater Complex of Montana, USA. A fine-grained, high-magnesium (high-Mg) dike in the Mountain View area of the complex is a plausible example of the type of magma that was parental to the layered cumulate rocks in the ultramafic series. Modeled ass...
Article
Full-text available
We have modeled the genesis of primary mantle-derived magma to explore the controls exerted on its Ni-Cu ore potential by water content, pressure, and mantle potential temperature (Tp). During decompression melting, Ni concentration in primary magma decreases with an increasing degree of melting, which is in contradiction to long-held understanding...
Article
Full-text available
Most of the world's major deposits of nickel and copper were formed as accumulations of magmatic sulfide liquid within small mafic-ultramafic intrusions. Ore-hosting intrusions exhibit a variety of forms but typically show greater horizontal than vertical extents, occurring as tube-shaped chonoliths, narrow elongate sills, boatshaped bodies, or swo...
Article
The origins of apparently magmatic Fe-P-O deposits like those of the El Laco volcanic complex, Chile, with masses on the order of 1 Gt remain contentious. Previous attention has been focused largely on the high-tonnage massive magnetite bodies that form the economic mineral deposits. Extensive occurrences of unconsolidated granular Fe-P-oxide mater...
Book
Full-text available
Overview of the geochemistry of magmatic and hydrothermal processes affecting PGE mineral deposits, review of ore deposit models, exploration methods, and several exploration case studies
Presentation
Full-text available
We examine the nature of the layering in the ultramafic rocks of the Stillwater Complex of Montana, USA. A fine-grained, high-magnesium dike in the Mountain View area of the complex is a plausible parental magma for the layered cumulate rocks in the Ultramafic series. Modeled crystal fractionation of a liquid with the composition of the dike produc...
Article
A large proportion of ores in magmatic sulfi de deposits consist of mixtures of cumulus silicate minerals, sulfi de liquid, and silicate melt, with characteristic textural relationships that provide essential clues to their origin. Within silicate-sulfi de cumulates, there is a range of sulfi de abundance in magmatic-textured silicate-sulfi de ores...
Article
The largest mass extinction event in Earth's history marks the boundary between the Permian and Triassic Periods at circa 252 Ma and has been linked with the eruption of the basaltic Siberian Traps large igneous province (SLIP). One of the kill mechanisms that has been suggested is a biogenic methane burst triggered by the release of vast amounts o...
Article
Full-text available
Layered intrusions represent part of the plumbing systems that deliver vast quantities of magma through the Earth's crust during the formation of large igneous provinces, which disrupt global ecosystems and host most of the Earth's endowment of Pt, Ni and Cr deposits. The Rustenburg Layered Suite of the enormous Bushveld Igneous Complex of South Af...
Data
Statistics used to determine the significance of age differences between dated samples from the RLS of the Bushveld Complex
Data
Compositions of rocks in the UG2 Unit and its mafic hanging wall.
Data
U-Pb ID-TIMS isotopic data for chemically abraded zircon grains and untreated baddeleyite crystals, Critical Zone, Rustenburg Layered Suite, Bushveld Complex, South Africa.
Data
Supplementary Figures 1-3, Supplementary Note 1 and Supplementary References.
Data
Summary log of diamond drill hole TF3, Critical Zone, Rustenburg Layered Suite, Bushveld Complex, South Africa.
Article
The Tootoo and Mequillon Ni-Cu-Pt-Pd deposits in the South Raglan Trend of the New Quebec orogen host significant but as yet unexploited nickel-copper-platinum group element (PGE) mineralization within the maficultramafic rocks of the Expo Intrusive Suite. The olivine melagabbronorite host rocks have been pervasively altered to hydrous mineral asse...
Article
Cratonic lithospheric mantle is composed of predominantly refractory materials that formed at higher mantle potential temperatures ( T P) than recorded in non-cratonic peridotites. It also shows stronger depletion and fractionation of Pd and Pt from Ru, Os and Ir than oceanic, supra-subduction zone or off-cratonic lithospheric mantle, as well as so...
Article
Full-text available
The formation of platinum-group minerals (PGM) during magma differentiation has been suggested to be an important process in primitive magma evolution, but decisive textural evidence is difficult to obtain because PGM tend to be very small and very rare. We have investigated Cr-spinel phenocrysts from two oxidized magmas (Siberian meimechite and Va...
Article
Full-text available
The formation of platinum-group minerals (PGM) during magma differentiation has been suggested to be an important process in primitive magma evolution, but decisive textural evidence is difficult to obtain because PGM tend to be very small and very rare. We have investigated Cr-spinel phenocrysts from two oxidized magmas (Siberian meimechite and Va...
Conference Paper
Full-text available
Chromitite bodies of various sizes occur within the mantle of the Khajeh-Jamali ophiolite, southern Iran. The Cheshmeh-Bid chromitite deposit is located into the mantle-crust transition zone and is separated from the host harzburgites by dunite envelopes. Platinum Group Element (PGE) contents from three massive chromitite samples from the Cheshmeh-...
Article
A large data compilation has been assembled of platinum group element (PGE) analyses in mantle melts and mantle rocks, the latter including an assortment of xenoliths and obducted mantle massifs. The degree of correlation has been investigated among the PGEs and with other major element variables such as Al2O3, TiO2 and Mg number, and the results a...
Article
The interstitial melt in partially molten cumulate piles in layered intrusions must at some point reach saturation with a volatile phase such as water vapor or hydrosaline melt. A number of models have been proposed in which orthomagmatic fluids migrate through partially solidified cumulates and participate in the formation of ore deposits. Here I...
Article
The Dumont sill in the Abitibi region of Quebec is a zoned intrusive body which is differentiated into a lower ultramafic zone, composed of peridotite and dunite, overlain by a mafic zone, with clinopyroxenite, gabbro, and quartz gabbro subzones. Although the dunite contains several layers enriched in primary Ni sulfide minerals, which add consider...
Article
Emissions of sulphur and metals from magmas in Earth’s shallow crust can have global impacts on human society. Sulphur-bearing gases emitted into the atmosphere during volcanic eruptions affect climate, and metals and sulphur can accumulate in the crust above a magma reservoir to form giant copper and gold ore deposits, as well as massive sulphur a...
Article
Emissions of sulphur and metals from magmas in Earth's shallow crust can have global impacts on human society. Sulphur-bearing gases emitted into the atmosphere during volcanic eruptions affect climate, and metals and sulphur can accumulate in the crust above a magma reservoir to form giant copper and gold ore deposits, as well as massive sulphur a...
Article
The partitioning of platinum-group elements (PGE; Os, Ir, Ru, Rh, Pt, and Pd) and Au between sulfide melt and silicate melt (i.e., DPGEsul) exerts a critical control on the PGE composition of the Earth’s crust and mantle, but previous estimates have been plagued by experimental uncertainties and vary through several orders of magnitude. Here we pre...
Article
The generation of ores from igneous rocks depends on the operation of common igneous processes in uncommon ways. Deposits of incompatible lithophile elements form when magmas containing unusually high concentrations of these rare elements fail to freeze at eutectic points, permitting their enrichment by extreme degrees of fractional crystallization...
Article
We have investigated experimentally the partitioning of Au between solid and liquid sulfide phases and basaltic melts at 200 MPa, at redox conditions close to the sulfide-sulfate transition, over temperatures between 1050 and 1200 °C, which span the monosulfide solid solution (MSS) - sulfide liquid (SuL) solidus. The measured MSS/basalt partition c...
Article
A discrete conductive sphere model in which current paths are constrained to a single planar orientation (the ‘dipping sphere’) is used to calculate the secondary response from Geotech Ltd’s VTEM airborne time domain electromagnetic (EM) system. In addition to calculating the time constants of the B-field and dB/dt responses, we focus on the time-c...
Article
We present new data for platinum group element (PGE) concentrations in lavas of several types from the southwestern Pacific region. The suite includes potassic to ultrapotassic basalts from Mts Hagen and Bosavi in Papua New Guinea; arc picrites from New Georgia; boninites from Chichi Jima and from both the northern Tonga arc and its back-arc basin;...
Chapter
Geophysical surveys have played a defining role in the discovery and subsequent delineation of many nickel, copper, and platinum group element (Ni-Cu-PGE) deposits. The high conductivity of pyrrhotite and the robustness of the electromagnetic methods that have been developed to directly detect this mineral are responsible for the exploration succes...
Chapter
The Eagle’s Nest Ni-Cu-PGE deposit was discovered in the McFaulds Lake area of the James Bay lowlands of northern Ontario, Canada, in 2007 by Noront Resources Ltd. It is a magmatic sulfide deposit hosted by mafic and ultramafic rocks interpreted to be a feeder conduit beneath an extensive complex of sills and related volcanic rocks, which range in...
Article
The migration of dense Fe-rich immiscible liquids through partially molten silicates is of critical importance to several issues including the formation of magmatic sulfide ore deposits and the formation of metallic cores in terrestrial planets. The migration of immiscible dense liquids can be considered to occur in three distinct regimes dictated...
Article
The El Laco volcano of northern Chile is noted for its controversial iron ore deposits, which some researchers regard as examples of iron oxide lava flows but others regard as epithermal deposits replacing pre-existing silicate lava flows. Lava flows with textures and structures typical of ordinary silicate lavas are composed entirely of magnetite....
Article
The Oligocene Yao’an syenite porphyry, associated with gold mineralisation, and the Machangqing alkali granite porphyry–monzonite porphyry, associated with Cu mineralisation, belong to the Red River–Jinshajiang alkaline igneous belt that formed in a continental setting in southwestern China. A study of the mineral chemistry of major silicate minera...
Article
Low Sulphide mineralisation occurs within the footwall of the Sudbury Igneous Complex. Samples of mineralised material have been collected from five properties and analysed using petrographic, microthermometric, point and bulk geochemical techniques. Two distinct mineralisation types have been identified for the North range (NR), a magmatic chalcop...
Article
The conventional classification of chromitite into two principal varieties, stratiform and podiform, fails to account for an important third type which is exemplified by the Kemi Deposit of Finland, the Ipueira-Medrados deposit in Brazil, and the Sukinda deposits of India. Stratiform deposits are widely recognized as regionally extensive layers up...
Article
Samples of fresh glassy high-Ca boninites and associated lavas from the northern Tonga region were dredged during the 2004 NoToVe cruise by the RV Southern Surveyor. We present the major element, trace element, and low-level PGE and Au concentrations of samples from Volcano A of the arc front, and from the Fonualei Rift and Mangatolu Triple Junctio...
Article
Full-text available
Chromite is widely recognized to act as a collector for platinum group elements (PGE), which tend to be observed as discrete grains of platinum group minerals included within magmatic chromite grains. In the course of experiments involving the re-equilibration or growth of chromite and Cr-spinel in molten silicate, we observe that platinum group mi...
Article
Full-text available
The formation of ore deposits of the platinum-group elements (PGE) requires that their concentrations be raised about four orders of magnitude above typical continental crustal abundances. Such extreme enrichment relies principally on the extraction capacity of sulfide liquid, which sequesters the PGE from silicate magmas. Specific aspects of PGE o...
Article
Full-text available
Fluid and melt inclusions trapped in igneous rocks below the platinum-group element (PGE)-rich J-M reef in the Stillwater Complex, Montana provide a physiochemical record of a continuum of high P–T magmatic–hydrothermal and low P–T metamorphic events. Magmatic–hydrothermal volatiles ranged from NaCl-dominated halide melts (>82 wt % NaCl equiv ) to...
Article
I present an empirical parameterization of low-pressure melting relations of monosulfide solid solution in the system Ni Cu Fe S O and use it to argue that sulfide ores at Sudbury are almost exclusively cumulate in origin. In the model the solid is considered to be composed of four components NiS, CuS, FeS, and S, where S represents substitution of...
Article
The Proterozoic Expo Intrusive Suite comprises a series of mafic to ultramafic intrusions crosscutting the Povungnituk Group of the Cape Smith Fold Belt in New Quebec. The intrusions are mainly in the form of blade-shaped dikes that penetrate a sediment-rich horizon in the middle of the Beauparlant Formation and terminate down- ward against massive...
Article
Full-text available
Understanding of the geochemistry of the chalcophile elements [i.e., Os, Ir, Ru, Pt, Pd (platinum-group elements), and Au, Cu, Ni] has been informed for at least 20 years by the common assumption that when crust-forming partial melts are extracted from the upper mantle, sulfide liquid in the restite sequesters chalcophile elements until the extent...
Article
We report methane-dominant hydrocarbon (fluid) inclusions (CH4±C2H6–C2H2, C3H8) coexisting with primary brine inclusions and secondary halide melt (solid NaCl) inclusions in Au–Pt-rich quartz-sulfide-epidote alteration veins associated with the footwall-style Cu–PGE (platinum-group element)–Au deposits at the Fraser Mine (North Range of the Sudbury...
Article
Full-text available
Ungavaite, Pd4Sb3, is a new intermetallic mineral species discovered in the Mesamax Northwest deposit, Cape Smith fold belt, Ungava region, northern Quebec. It is associated with monoclinic pyrrhotite, pentlandite, chalcopyrite, galena, sphalerite, cobaltite, a chlorite-group mineral and magnetite. Associated precious-metal minerals include another...
Article
We have performed six experiments in which we equilibrated monosulfide solid solution (mss) with sulfide melt in evacuated silica capsules containing solid buffers to fix oxygen and sulfur fugacity, at temperatures of 950°C, 1000°C and 1050°C at bulk concentrations of ∼50 ppm for each of the PGE and Au, 5% Ni, and 7% Cu. Concentrations of O, S, Fe,...