Constraints on temperature–pressure conditions and fluid composition during metamorphism of the Sullivan orebody, Kimberley, British Columbia, from silicate–carbonate equilibria

1995 ◽  
Vol 32 (11) ◽  
pp. 1937-1949 ◽  
Author(s):  
Glen R. De Paoli ◽  
David R.M. Pattison
Keyword(s):  
British Columbia ◽  
Ore Deposits ◽  
Garnet Growth ◽  
Fluid Composition ◽  
Exchange Equilibrium ◽  
Low Grade ◽  
Metamorphic Temperature ◽  
Lower Temperature ◽  
Silicate Carbonate ◽  
Peak Metamorphic Temperature

The Sullivan mine, in southeastern British Columbia, is one of the world's largest sediment-hosted, massive sulphide deposits. It has undergone at least one period of metamorphism since it was deposited in mid-Proterozoic times. Mineral textures within the deposit are predominantly of metamorphic origin. A well-constrained estimate of metamorphic conditions is required to understand how the original, depositional character of the orebody has been modified by metamorphism. Metamorphic conditions were estimated using multiequilibrium thermobarometric techniques involving silicate–carbonate–fluid equilibria. Peak metamorphic temperature constrained by calibration of the garnet–biotite Fe–Mg exchange equilibrium is 450 ± 50 °C. Lower temperature estimates from some samples are interpreted to record the temperature of cessation of garnet growth prior to the attainment of peak metamorphic temperature. Peak metamorphic pressure as determined from equilibria applicable to the assemblage garnet–biotite–muscovite–chlorite–calcite–quartz–fluid is 380 ± 100 MPa. The fluid composition accompanying this pressure estimate is [Formula: see text], [Formula: see text]. This estimate is particular to one sample and may not be representative for the deposit as a whole. Metamorphic fluids at the estimated P–T conditions would not have contained significant concentrations of C–O–H–S species other than H2O and CO2. Textural evidence and temperature–pressure results from a titanite-bearing metamorphosed mafic intrusion in the deposit suggest published titanite ages near 1330 Ma in the area of the mine represent the age of the peak metamorphic event. The results of this study carry tectonic implications for the Sullivan area, and may have application to other metamorphosed ore deposits and low-grade metamorphic settings.

Application of Laser Induced Luminescence in Ecology

1993 ◽  
Vol 27 (7-8) ◽  
pp. 547-556 ◽  
Author(s):  
M. Gaft
Keyword(s):  
New Technology ◽  
Ore Deposits ◽  
Ecological Effects ◽  
Low Grade ◽  
Ecological Damage

Exhaustion of rich ore deposits is making it necessary to bring low-grade ores into production, resulting in a sharply increased volume of excavated rock. Huge quantities of waste fill vast areas of the Earth's surface, with severe ecological effects. But the ecological damage could be reduced by extracting additional products from the tailings. Laseroluminescent sorting is a new technology by which this may be achieved. The most promising subjects are about 50 minerals including diamonds, native Au and Ag, ores of V, Pb, Zn, Sn, Li, Be, W, Mo, Zr, Sr, halite, apatite, phosphorite, fluorite, calcite, barite, anhydrite.

scholarly journals Impact of Sodium Hexametaphosphate on the Flotation of Ultrafine Magnesite from Dolomite-Rich Desliming Tailings

Minerals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 499
Author(s):  
Duong Huu Hoang ◽  
Doreen Ebert ◽  
Robert Möckel ◽  
Martin Rudolph
Keyword(s):  
Ultrafine Particles ◽  
Raw Materials ◽  
Low Cost ◽  
Froth Flotation ◽  
Open Circuit ◽  
Ore Deposits ◽  
Sodium Hexametaphosphate ◽  
Low Grade ◽  
Low Contrast ◽  
The Impact

The depletion of ore deposits, the increasing demand for raw materials, the need to process low-grade, complex and finely disseminated ores, and the reprocessing of tailings are challenges especially for froth flotation separation technologies. Even though they are capable of handling relatively fine grain sizes, the flotation separation of very fine and ultrafine particles faces many problems still. Further, the flotation of low-contrast semi-soluble salt-type minerals with very similar surface properties, many complex interactions between minerals, reagents and dissolved species often result in poor selectivity. This study investigates the flotation beneficiation of ultrafine magnesite rich in dolomite from desliming, currently reported to the tailings. The paper especially focuses on the impact of the depressant sodium hexametaphosphate (SHMP) on the following: (i) the froth properties using dynamic froth analysis (DFA), (ii) the separation between magnesite and dolomite/calcite, and (iii) its effect on the entrainment. As a depressant/dispersant, SHMP has a beneficial impact on the flotation separation between magnesite and dolomite. However, there is a trade-off between grade and recovery, and as well as the dewatering process which needs to be considered. When the SHMP increases from 200 g/t to 700 g/t, the magnesite grade increases from 67% to 77%, while recovery decreases massively, from 80% to 40%. The open circuit with four cleaning stages obtained a concentrate assaying 77.5% magnesite at a recovery of 45.5%. The dolomite content in the concentrate is about 20%, where 80% of dolomite was removed and importantly 98% of the quartz was removed, with only 0.3% of the quartz in the final concentrate. Furthermore, the application of 1-hydroxyethylene-1,1-diphosphonic acid (HEDP) as a more environmentally friendly and low-cost alternative to SHMP is presented and discussed. Using only 350 g/t of HEDP can achieve a similar grade (76.3%), like 700 g/t of SHMP (76.9%), while obtaining a 17% higher magnesite recovery as compared to 700 g/t of SHMP. Interestingly, the proportion of hydrophilic quartz minerals ending up in the concentrate is lower for HEDP, with only 1.9% quartz at a recovery of 21.5% compared to the 2.7% of quartz at a recovery of 24.9% when using SHMP. The paper contributes in general to understanding the complexity of the depressant responses in froth flotation.

Native Copper, Silver, and Gold Accessible to Early Metallurgists

1971 ◽  
Vol 36 (3) ◽  
pp. 286-321 ◽  
Author(s):  
Clair C. Patterson
Keyword(s):  
New World ◽  
Silver Halide ◽  
Ore Deposits ◽  
Sulfide Ores ◽  
Lead Carbonate ◽  
Native Copper ◽  
Ancient Times ◽  
Geological Sciences ◽  
Metallic Impurities ◽  
Silicate Carbonate

AbstractThe weathered zones of ore deposits, which no longer exist, are reconstructed by inference to provide estimates of relative abundances of usable nuggets of native copper, silver, and gold in ancient times. New analyses and selected data from the literature summarize metallic impurities in native copper, silver, gold, and lead and in the oxidized copper minerals, oxide, silicate, carbonate, chloride, and sulfate, together with impurities in lead carbonate and silver halide minerals. The influence that these occurrences and compositions exerted upon the origin and development of metallurgy in Mesoamerica and South America is discussed in relation to new analyses of artifacts and selected data from the literature. Topics emphasized are: the discovery of smelting and melting by the Moche; the inability of New World metallurgists to smelt copper from sulfide ores or silver from lead ores; and the lack of influence by transoceanic contacts. This paper is contribution number 1702 of the Division of Geological Sciences, C.I.T.

Are Vapor-Like Fluids Viable Ore Fluids for Cu-Au-Mo Porphyry Ore Formation?

2021 ◽  
Author(s):  
Nicole C. Hurtig ◽  
Artas A. Migdisov ◽  
Anthony E. Williams-Jones
Keyword(s):  
Fluid Inclusions ◽  
Metal Content ◽  
Ore Deposits ◽  
Fluid Composition ◽  
Ore Formation ◽  
Metal Solubility ◽  
Gas Condensates ◽  
Intermediate Density ◽  
Metallic Species ◽  
Metal Ratios

Abstract Ore formation in porphyry Cu-Au-(Mo) systems involves the exsolution of metal-bearing fluids from magmas and the transport of the metals in magmatic-hydrothermal plumes that are subject to pressure fluctuations. Deposition of ore minerals occurs as a result of cooling and decompression of the hydrothermal fluids in partly overlapping ore shells. In this study, we address the role of vapor-like fluids in porphyry ore formation through numerical simulations of metal transport using the Gibbs energy minimization software, GEM-Selektor. The thermodynamic properties of the hydrated gaseous metallic species necessary for modeling metal solubility in fluids of moderate density (100–300 kg/m3) were derived from the results of experiments that investigated the solubility of metals in aqueous HCl- and H2S-bearing vapors. Metal transport and precipitation were simulated numerically as a function of temperature, pressure, and fluid composition (S, Cl, and redox). The simulated metal concentrations and ratios are compared to those observed in vapor-like and intermediate-density fluid inclusions from porphyry ore deposits, as well as gas condensates from active volcanoes. The thermodynamically predicted solubility of Cu, Au, Ag, and Mo decreases during isothermal decompression. At elevated pressure, the simulated metal solubility is similar to the metal content measured in vapor-like and intermediate-density fluid inclusions from porphyry deposits (at ~200–1,800 bar). At ambient pressure, the metal solubility approaches the metal content measured in gas condensates from active volcanoes (at ~1 bar), which is several orders of magnitude lower than that in the high-pressure environment. During isochoric cooling, the simulated solubility of Cu, Ag, and Mo decreases, whereas that of Au reaches a maximum between 35 ppb and 2.6 ppm depending on fluid density and composition. Similar observations are made from a compilation of vapor-like and intermediate-density fluid inclusion data showing that Cu, Ag, and Mo contents decrease with decreasing P and T. Increasing the Cl concentration of the simulated fluid promotes the solubility of Cu, Ag, and Au chloride species. Molybdenum solubility is highest under oxidizing conditions and low S content, and gold solubility is elevated at intermediate redox conditions and elevated S content. The S content of the vapor-like fluid strongly affects metal ratios. Thus, there is a decrease in the Cu/Au ratio as the S content increases from 0.1 to 1 wt %, whereas the opposite is the case for the Mo/Ag ratio; at S contents of >1 wt %, the Mo/Ag ratio also decreases. In summary, thermodynamic calculations based on experiments involving gaseous metallic species predict that vapor-like fluids may transport and efficiently precipitate metals in concentrations sufficient to form porphyry ore deposits. Finally, the fluid composition and pressure-temperature evolution paths of vapor-like and intermediate-density fluids have a strong effect on metal solubility in porphyry systems and potentially exert an important control on their metal ratios and zoning.

Isolation, Identification and Screening of Manganese Solubilizing Fungi From Low-Grade Manganese Ore Deposits

2016 ◽  
Vol 34 (4) ◽  
pp. 309-316 ◽  
Author(s):  
S. Mohanty ◽  
S. Ghosh ◽  
S. Nayak ◽  
A. P. Das
Keyword(s):  
Ore Deposits ◽  
Low Grade ◽  
Manganese Ore

scholarly journals Endoscopic Mucosal Resection: Early Experience in British Columbia

2010 ◽  
Vol 24 (4) ◽  
pp. 239-244 ◽  
Author(s):  
Mayur Brahmania ◽  
Eric Lam ◽  
Jennifer Telford ◽  
Robert Enns
Keyword(s):  
British Columbia ◽  
Barrett’S Esophagus ◽  
Endoscopic Mucosal Resection ◽  
Barrett's Esophagus ◽  
Low Grade ◽  
Complication Rates ◽  
The Third ◽  
Mucosal Resection ◽  
The Mean

BACKGROUND: Endoscopic mucosal resection (EMR) has been proposed as a primary method of managing patients with dysplasia- or mucosal-based cancers of the esophagus.OBJECTIVES: To evaluate the use of EMR for the treatment of Barrett’s esophagus with dysplasia or early adenocarcinoma, assessing efficacy, complication rates and long-term outcomes.METHODS: All patients who underwent EMR at St Paul’s Hospital (Vancouver, British Columbia) were reviewed. Eligible patients were assessed with aggressive biopsy protocols. Detected cancers were staged with both endoscopic ultrasound imaging and computed tomography. Appropriate patients were offered EMR using a commercially available mucosectomy device. EMR was repeated at six- to eight-week intervals until complete. Patients with less than one year of follow-up or who were undergoing other ablative methods were excluded.RESULTS: Twenty-two patients (all men) with a mean (± SD) age of 67±10.6 years were identified. The mean duration of gastroesophageal reflux disease was 17 years (range four to 40 years) and all were receiving proton pump inhibitor therapy. The mean length of Barrett’s esophagus was 5.5±3.5 cm. One patient had no dysplasia (isolated nodule), three had low-grade dysplasia, 15 had high-grade dysplasia (HGD) and three had adenocarcinoma. A mean of 1.7±0.83 endoscopic sessions were performed, with a mean of 6±5.4 sections removed. Following EMR, three patients developed strictures; two of these patients had pre-existing strictures and the third required two dilations, which resolved his symptoms. There were no other complications. Three patients underwent esophagectomy. Two had adenocarcinoma or HGD in a pre-existing stricture. The third patient had an adenocarcinoma not amenable to EMR. One patient with a long segment of Barrett’s esophagus underwent radiofrequency ablation. At a median follow-up of two years (range one to three years), the remaining 18 patients (82%) had no evidence of HGD or cancer.CONCLUSION: Most patients with esophageal dysplasia can be managed with EMR. Individuals with pre-existing strictures require other endoscopic and/or surgical methods to manage their dysplasia or adenocarcinoma.

Chlorite and Epidote Mineral Chemistry in Porphyry Ore Systems: A Case Study of the Northparkes District, New South Wales, Australia

2020 ◽  
Vol 115 (4) ◽  
pp. 701-727 ◽  
Author(s):  
Adam Pacey ◽  
Jamie J. Wilkinson ◽  
David R. Cooke
Keyword(s):  
New South ◽  
New South Wales ◽  
Mineral Chemistry ◽  
Ore Deposits ◽  
Low Grade ◽  
South Wales ◽  
Spatial Trends ◽  
Propylitic Alteration ◽  
Mineral Partitioning

Abstract Propylitic alteration, characterized by the occurrence of chlorite and epidote, is typically the most extensive and peripheral alteration facies developed around porphyry ore deposits. However, exploration within this alteration domain is particularly challenging, commonly owing to weak or nonexistent whole-rock geochemical gradients and the fact that similar assemblages can be developed in other geologic settings, particularly during low-grade metamorphism. We document and interpret systematic spatial trends in the chemistry of chlorite and epidote from propylitic alteration around the E48 and E26 porphyry Cu-Au deposits of the Northparkes district, New South Wales, Australia. These trends vary as a function of both distance from hydrothermal centers and alteration paragenesis. The spatial trends identified in porphyry-related chlorite and epidote at Northparkes include (1) a deposit-proximal increase in Ti, As, Sb, and V in epidote and Ti in chlorite, (2) a deposit-distal increase in Co and Li in chlorite and Ba in epidote, and (3) a pronounced halo around deposits in which Mn and Zn in chlorite, as well as Mn, Zn, Pb, and Mg in epidote, are elevated. Chlorite Al/Si ratios and epidote Al/Fe ratios may show behavior similar to that of Mn-Zn or may simply decrease outward, and V and Ni concentrations in chlorite are lowest in the peak Mn-Zn zone. In comparison to porphyry-related samples, chlorite from the regional metamorphic assemblage in the district contains far higher concentrations of Li, Ca, Ba, Pb, and Cu but much less Ti. Similarly, metamorphic epidote contains higher concentrations of Sr, Pb, As, and Sb but less Bi and Ti. These chlorite and epidote compositional trends are the net result of fluid-mineral partitioning under variable physicochemical conditions within a porphyry magmatic-hydrothermal system. They are most easily explained by the contribution of spent magmatic-derived ore fluid(s) into the propylitic domain. It is envisaged that such fluids experience progressive cooling and reduction in fs2 during outward infiltration into surrounding country rocks, with their pH controlled by the extent of rock-buffering experienced along the fluid pathway.

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