Pedro Jugo

Laurentian University · Mineral Exploration Research Centre

We demonstrate the application potential of laser-ablation - inductively coupled plasma - mass spectrometry (LA-ICP-MS) to map the distribution of major and trace elements in a variety of samples. The examples cover a wide range of elements, including the rare-earth elements (REE) and platinum-group elements (PGE). In order to test the capabilities...

Accurate estimates of the sulfur content in silicate melts at sulfi de saturation are required to explain magmatic processes such as the origin and budget of sulfur in some volcanic erup- tions and the transfer of Cu, Au, and other precious metals from the mantle to the crust via partial melting of the mantle. A model that links S speciation, S con...

Shock veins and melt pockets in Lithology A of Martian meteorite Elephant Moraine (EETA) 79001 have been investigated using electron microprobe (EM) analysis, petrography and X-ray Absorption Near Edge Structure (XANES) spectroscopy to determine elemental abundances and sulfur speciation (S²⁻ versus S⁶⁺). The results constrain the materials that me...

XANES analyses at the sulfur K-edge were used to determine the oxidation state of S species in natural and synthetic basaltic glasses and to constrain the fO2 conditions for the transition from sulfide (S2−) to sulfate (S6+) in silicate melts. XANES spectra of basaltic samples from the Galapagos spreading center, the Juan de Fuca ridge and the Lau...

Magmas are an important source of noble metals. Metals are transported by magma from deep within the mantle to the shallow crust, where they form subsurface ore deposits. The concentration of noble metals in silicate melts has been thought to be controlled by the stability of sulphide minerals in the upper mantle and crust, with only sulphide-under...

Chromitite petrogenesis in layered intrusions is important because some chromitites host economic Ni-Cu-platinum group element mineralization. Cryptic layering, which could be useful to reconstruct the chromitite origin, has been documented for some chromitites. Here, we document cm-scale stratigraphic profiles of the major and trace element conten...

Oxidized, sulfur-rich arc magmas are ubiquitous in modern subduction-zone environments. These magmas are thought to form when the fluids released during prograde metamorphism of subducting oceanic crust and overlying sediments oxidize and hydrate the asthenospheric mantle. In contrast, Archaean arc-type magmas are thought to be relatively reduced a...

The UG-2 chromitite layer, with its elevated platinum-group element content, is a key marker horizon in the eastern and western limbs of the Bushveld Igneous Complex and the largest platinum-group element chromite-hosted resource of its kind in the world. In contrast, much less is known about its stratigraphic equivalent in the northern limb, the “...

Most known porphyry Cu ± Au deposits are associated with moderately oxidized and sulfur-rich, calc-alkaline to mildly alkalic arc-related magmas in the Phanerozoic. In contrast, sodium-enriched tonalite-trondhjemite-granodiorite-diorite (TTG) magmas predominant in the Archean are hypothesized to be unoxidized and sulfur-poor, which together preclud...

Arc magmas lead to the formation of porphyry deposits in the relatively shallow upper crust (less than 5 km depth). Porphyry deposits are major sources of Cu and an important Au source but lack significant amounts of platinum-group elements (PGE). Sulfide phases control the behavior of chalcophile elements and affect the potential to form ore depos...

Most known porphyry Cu deposits formed in the Phanerozoic and are exclusively associated with moderately oxidized, sulfur-rich, hydrous arc-related magmas derived from partial melting of the asthenospheric mantle metasomatized by slab-derived fluids. Yet, whether similar metallogenic processes also operated in the Precambrian remains obscure. Here...

The Bushveld Igneous Complex (BIC) is known for its laterally extensive platinum group element–bearing layers, the most famous being the Merensky Reef and the UG-2 chromitite in the eastern and western limbs of the complex. In the northern limb, the Platreef mineralization and a thick chromitite seam below it (referred to as the “UG-2 equivalent” o...

The origin of PGE-Ni-Cu mineralization in the Platreef, northern limb of the Bushveld Igneous Complex (BIC), and the possible correlation with the Merensky Reef in the eastern and western limbs has been long debated. The Platreef and Merensky Reef share the same stratigraphic position in the uppermost part of the Upper Critical Zone (UCZ), near the...

The proximity to metasedimentary footwall rocks relative to platinum group element (PGE) mineralized intrusive rocks in the northern limb of the Bushveld Igneous Complex (BIC) has resulted in complex local contamination in the intrusions. To assess the extent of incorporation of non-magmatic material and its effects on PGE mineralization, major ele...

More than 30 years ago, Cox and Singer (1986) suggested that magmatic platinum-group element (PGE)-Ni-Cu deposits are amongst the best understood of ore deposits, yet the origin of PGE mineralization in the Bushveld Igneous Complex (BIC) remains controversial after a century of study. In the northern limb of the BIC, the unravelling of ore formatio...

The Bushveld Igneous Complex (BIC) is known for its laterally extensive PGE-bearing layers, the most famous being the Merensky Reef and the UG-2 chromitite in the Eastern and Western limbs of the BIC. In the Northern Limb, the Platreef and a thick chromitite seam below (henceforth the "UG-2 equivalent" or UG-2E) have been proposed to be the extensi...

Previous studies in the Eastern and Western Limbs of the Bushveld Igneous Complex (BIC) have documented variations in the 87 Sr/ 86 Sri values across the Upper Critical Zone (UCZ) that mark the stratigraphic position of PGE-Ni-Cu mineralization at the Merensky Reef, as well as 34 S values that do not match mantle estimates but can be considered cha...

The Platreef is generally characterized by interaction of Bushveld magmas with underlying metasedimentary rocks or granitoids and it is of interest because of the PGE-Ni-Cu mineralization it contains. One puzzling aspect is the lack of correlation between PGE-Ni-Cu contents and sulfide abundance, which is relevant because of the role of sulfide sat...

Pyrite, the most abundant sulfide in the Earth’s crust, is an accessory mineral in several magmatic sulfide deposits. Although most pyrite is hydrothermal, previous experimental studies have shown that pyrite can also have a primary magmatic origin, by exsolving from monosulfide solid solution (mss) during cooling of a sulfide melt, if sulfur fugac...

Exsolution of semimetal liquids from sulfides: Experimental study on the solubility of Te-Bi-As liquids in monosulfide solid solution between 1050 °C and 600 °C Cafagna, F. and Jugo, P.J., Laurentian University, 395, Ramsey Lake Road, Sudbury, ON P3E 2C6, fx_cafagna@laurentian.ca Semimetals (e.g., Te, Bi and As) are thought to exsolve immiscible l...

Experimental study on the mobility of highly siderophile elements complexed with Te, Bi, and As. Cafagna, F. and Jugo, P.J., Laurentian University, Dept. Earth Sciences, 935 Ramsey Lake Rd., Sudbury, ON P3E 2C6, fx_cafagna@laurentian.ca Platinum Group Elements (PGE: Ru, Rh, Pd, Os, Ir, Pt) and Highly Siderophile Elements (HSE: PGE, plus Re and A...

Knowledge on the behaviour of sulphur in natural magmas provides important constraints on geochemical and geophysical processes occurring in magmatic and hydrothermal systems. The partitioning of S between silicate melts and coexisting fluids is mainly controlled by the transformations of S species into sulphide or sulphate form due to changes in t...

Major and trace element chemistry, as well as sulfur speciation, has been characterized in EET 79001 shock melts in order to constrain the materials which were melted to form them. Our results support in situ formation of shock melts.

The origin of sulfite (S4+) species in silicate glasses was evaluated using XANES at the S K-edge. Systematic investigations show that the presence of S4+ species in silicate glasses is an analytical artifact related to changes in the sulfur species caused by irradiation with an electron beam during EMPA or by irradiation with an intense focused X-...

eTable 1 Major element compositions of clinopyroxene, olivine and amphibole given in terms of cations per formula unit (4, 6 and 24 oxygen basis for olivine, pyroxene and amphibole, respectively), Fe3+ contents were determined by Mössbauer spectroscopy.

The behavior if S in magmatic systems is of interest because of the impact of high-S explosive volcanism on climate, the controlling role of sulfides on the behavior of base and precious metals, and the potential use of S speciation as an indicator of the oxidation state of magmas. In silicate melts S can be present as sulfide (S2- ), sulfate (S6+)...

Clinopyroxene megacrysts and mineral aggregates with clinopyroxene occur in the volcanic deposits at Mont Briançon and Marais de Limagne, which are located in the northern part of the Devès volcanic field (Massif Central, France). The clinopyroxenes can be subdivided into five groups based upon their major and trace element chemistry. Types 1a, 1b...

Sulfur is an element of interest in magmatic processes for several reasons, some of which are related to the oxidation state of S during magma generation and evolution. For example, S as sulfide (S2-) controls the behavior of chalcophile and highly siderophile elements, whereas S as sulfate (S6+) is responsible for high- S explosive volcanic erupti...

The speciation of sulfur as a function of oxygen fugacity was calculated in glasses of basaltic composition saturated experimentally with either sulfide or sulfate phases. The experiments were conducted on mixtures of synthetic and natural materials equilibrated at 1300 °C and 1 GPa in a piston-cylinder apparatus. Sulfur speciation was calculated b...

The sulfur content in basaltic melts coexisting with either sulfide or sulfate melts was determined experimentally. The experimental conditions were in the range of 1300–1355°C and 1·0–1·6 GPa, conditions appropriate for the melting of the upper mantle above subduction zones. Under these conditions, both sulfide and sulfate were present as immiscib...

Although sulfur is a minor element in the Earth, it has a disproportionate impact because it commonly occurs as sulfide. Sulfides largely control the behavior of chalcophile (e.g., Cu, Ni) and highly siderophile elements (Ru, Rh, Pd, Re, Os, Ir, Pt, and Au) that are of interest because either they are economically important or because they provide...

Two sets of experiments were conducted to determine the differences in sulfur solubility in sulfide-saturated (reduced) vs. sulfate-saturated (oxidized) basaltic systems. The experiments were performed in a piston-cylinder apparatus at 1.2 GPa and 1315 \deg C, pressure and temperature roughly representative of conditions in the upper mantle. Five w...

The behavior of copper and gold in the phase assemblage: pyrrhotite (Po)–intermediate solid solution (Iss)–haplogranitic melt–gold metal (capsule) at 850°C, 100 MPa and gas saturation (aH2O≈0.9) has been investigated. The results are presented as Nernst partition coefficients. The partition coefficient, DCuPo/Melt=2.6±(0.3)×103 (1σ), was determined...

Fe and S are two heterovalent elements that play a major role in many geological processes. Although S occurs only as a trace element in magmatic systems its behavior is directly related to a variety of important geological processes (e.g. formation of ore deposits, global cooling by S-rich explosive volcanism). The solubility of sulfur depends str...

The causes for sulfide saturation a understood. Anhydrite assimilation can explain mechanism for sulfide precipitation because sulfate reductio magma significantly, potentially precluding simultaneously, anhydrite could be reacted to fo this may result in sulfide dispersion. Recent ex melts can dissolve r h t pe oughly 10 times more sulfu gmas get...

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Thesis (M.S.)--University of Maryland at College Park, 1997. Thesis research directed by Dept. of Geology. Includes bibliographical references (leaves 89-93).

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