scholarly journals Multi-stage sulfide evolution of the Moran Ni sulfide ore, Kambalda, Western Australia: insights into the dynamics of ore forming processes of komatiite-hosted deposits

2021 ◽  
Author(s):  
Sebastian Staude ◽  
Marcus Oelze ◽  
Gregor Markl
Keyword(s):  
Vertical Movement ◽  
Sulfide Deposit ◽  
Monosulfide Solid Solution ◽  
Massive Sulfides ◽  
Low Viscosity ◽  
Melt Pool ◽  
Incompatible Elements ◽  
Multi Stage ◽  
Sulfide Ore ◽  
Sulfide Melt

AbstractThe Moran komatiite-hosted Ni sulfide deposit at Kambalda (Australia) is one of the better preserved orebodies at Kambalda. Its geochemical signature is used to investigate the evolution of the sulfide mineralization. The orebody has several parts, including a flanking segment where massive sulfides formed relatively early and a central portion in a 40-m-deep erosional embayment representing a later generation of massive and net-textured sulfides. Basal massive sulfides within the deep embayment vary systematically in their chalcophile element contents (Ni, PGE, Au, Te, As, Bi). Elements compatible in monosulfide solid solution (MSS) exhibit the highest concentration at the edge of the orebody (up to 4.3 ppm Ir + Os + Ru + Rh), whereas incompatible elements are most concentrated in the centre (up to 11.2 ppm Pt + Pd + Au). This difference in element distributions is explained by fractional crystallization of sulfide melt from the edge towards the centre. To explain the vertical movement of the residual fractionated melt, a new model of sulfide crystallization is proposed. A low-viscosity boundary layer containing incompatible elements is formed between MSS and sulfide melt. This melt propagates with the crystallization front towards the centre of the sulfide melt pool. Trace element variations in pentlandite (e.g. Co) and composite Co- and Bi-bearing arsenide-telluride grains suggest that during the final stages of crystallization, an immiscible Co-As-Te-Bi melt is formed.

Nano- and Micrometer-Sized PGM in Ni-Cu-Fe Sulfides from an Olivine Megacryst in the Udachnaya Pipe, Yakutia, Russia

2021 ◽  
Vol 59 (6) ◽  
pp. 1755-1773
Author(s):  
José María González-Jiménez ◽  
Irina Tretiakova ◽  
Marco Fiorentini ◽  
Vladimir Malkovets ◽  
Laure Martin ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Field Emission ◽  
Platinum Group Element ◽  
Group Element ◽  
Monosulfide Solid Solution ◽  
Mineral Particles ◽  
Transmission Electron ◽  
Sulfide Melt ◽  
Platinum Group

ABSTRACT This paper focuses on a nanoscale study of nano- and micrometer-size Os-rich mineral particles hosted in a Ni-Fe-Cu sulfide globule found in an olivine megacryst from the Udachnaya pipe (Yakutia, Russia). These platinum-group element mineral particles and their host sulfide matrices were investigated using a combination of techniques, including field emission gun electron probe microanalyzer, field emission scanning electron microscopy, and focused ion beam and high-resolution transmission electron microscopy. The sulfide globule is of mantle origin, as it is hosted in primitive olivine (Fo90–93), very likely derived from the crystallization of Ni-Fe-Cu sulfide melt droplets segregated by liquid immiscibility from a basaltic melt in a volume of depleted subcontinental lithospheric mantle. Microscopic observations by means of field emission scanning electron microscopy and single-spot analysis and mapping by field emission gun electron probe microanalyzer reveal that the sulfide globule comprises a core of pyrrhotite with flame-like exsolutions (usually <10 μm thickness) of pentlandite, which is irregularly surrounded by a rim of granular pentlandite and chalcopyrite. Elemental mapping by energy dispersive spectroscopy (acquired using the high-resolution transmission electron microscopy) of the pyrrhotite (+ pentlandite) core reveals that pentlandite exsolution in pyrrhotite is still observable at the nanoscale as fringes of 100 to 500 nm thicknesses. The sulfide matrices of pyrrhotite, pentlandite, and chalcopyrite contain abundant nano- and micrometer-size platinum group element mineral particles. A careful inspection of eight of these platinum group element particles under focused ion beam and high-resolution transmission electron microscopy showed that they are crystalline erlichmanite (OsS2) with well-developed crystal faces that are distinctively oriented relative to their sulfide host matrices. We propose that the core of the Ni-Fe-Cu sulfide globule studied here was derived from a precursor monosulfide solid solution originally crystallized from a sulfide melt at >1100 °C, which later decomposed into pyrrhotite and the pentlandite flame-like exsolutions upon cooling at <600 °C. Once solidified, the solid monosulfide solid solution reacted with non-equilibrium Cu-and Ni-rich sulfide melt(s), giving rise to the granular pentlandite in equilibrium with chalcopyrite now forming the rim of the sulfide globule. Meanwhile, nano- to micron-sized crystals of erlichmanite crystallized directly from or slightly before monosulfide solid solution from the sulfide melt. Thus, Os, and to a lesser extent Ir and Ru, were physically partitioned by preferential uptake via early formation of nanoparticles at high temperature instead of low-temperature exsolution from solid Ni-Fe-Cu sulfides. The new data provided in this paper highlight the necessity of studying platinum group element mineral particles in Ni-Fe-Cu sulfides using analytical techniques that can image nanoscale textural features in order to better understand the mechanisms of platinum group element fractionation in magmatic systems. These processes may play a crucial role in controlling the background geochemical budgets for siderophile and chalcophile elements in a wide range of mantle-derived magmas.

Modeling Acid Fracturing Treatments with Multi-Stage Alternating Injection of Pad and Acid Fluids

2021 ◽  
Author(s):  
Rencheng Dong ◽  
Mary F. Wheeler ◽  
Hang Su ◽  
Kang Ma
Keyword(s):  
Viscous Fingering ◽  
High Viscosity ◽  
Carbonate Reservoirs ◽  
Acid Etching ◽  
Fracture Geometry ◽  
Fracture Conductivity ◽  
Acid Fracturing ◽  
Fracture Surfaces ◽  
Low Viscosity ◽  
Multi Stage

Abstract Acid fracturing technique is widely applied to stimulate the productivity of carbonate reservoirs. The acid-fracture conductivity is created by non-uniform acid etching on fracture surfaces. Heterogeneous mineral distribution of carbonate reservoirs can lead to non-uniform acid etching during acid fracturing treatments. In addition, the non-uniform acid etching can be enhanced by the viscous fingering mechanism. For low-perm carbonate reservoirs, by multi-stage alternating injection of a low-viscosity acid and a high-viscosity polymer pad fluid during acid fracturing, the acid tends to form viscous fingers and etch fracture surfaces non-uniformly. To accurately predict the acid-fracture conductivity, this paper developed a 3D acid fracturing model to compute the rough acid fracture geometry induced by multi-stage alternating injection of pad and acid fluids. Based on the developed numerical simulator, we investigated the effects of viscous fingering, perforation design and stage period on the acid etching process. Compared with single-stage acid injection, multi-stage alternating injection of pad and acid fluids leads to narrower and longer acid-etched channels.

scholarly journals Mineralogy of Nickel and Cobalt Minerals in Xiarihamu Nickel–Cobalt Deposit, East Kunlun Orogen, China

2020 ◽  
Vol 8 ◽  
Author(s):  
Yixiao Han ◽  
Yunhua Liu ◽  
Wenyuan Li
Keyword(s):  
Hydrothermal Process ◽  
Cobalt Sulfide ◽  
Sulfide Deposit ◽  
Crustal Material ◽  
Mechanism Model ◽  
Electron Probe Microanalyzer ◽  
Nickel Cobalt ◽  
East Kunlun ◽  
Metallogenic Mechanism ◽  
Sulfide Melt

Located in the East Kunlun Orogen, China, the Xiarihamu magmatic nickel–cobalt sulfide deposit is the country’s second largest deposit of this type. It was formed in special early Paleozoic with low copper grade (0.14 wt%) compared with other deposits of the same type. The mineralogy of nickel and cobalt minerals, which are direct carriers of these elements, can clearly reflect their behavior in the process of mineralization; however, such information for this deposit remains unreported. In the present study, we use an electron microscope and electron probe microanalyzer to delineate and analyze many nickel and cobalt minerals such as maucherite, nickeline, cobaltite, violarite, gersdorffite, parkerite, and arsenohauchecornite in various rocks and ores. With the increase in crustal material contamination, it can reach arsenide saturation locally in sulfide melt, then a separate Ni-rich arsenide (bismuth) melt exsolves somewhere. This melt will crystallize into nickeline, parkerite, arsenohauchecornite, and maucherite first. Second, most of nickel and cobalt tend to enter cobaltite and pentlandite phases, rather than existing in chalcopyrite and pyrrhotite phases as isomorphism during sufficient fractional crystallization of sulfide melt, which gathered nickel and cobalt elements widely. Also, more than one magma might result in the superposition of ore-forming elements. Later, the ore-forming elements redistribute limitedly through a hydrothermal process. The metallogenic mechanism model of nickel and cobalt established in the present study not only explains the process of nickel–cobalt mineralization in Xiarihamu but also can be applied to similar deposits and has a wide universal replicability.

Mineralogy and textural relationships of ores from the Whalesback Mine, northeastern Newfoundland

1968 ◽  
Vol 5 (6) ◽  
pp. 1387-1395 ◽  
Author(s):  
K. Kanehira ◽  
D. Bachinski
Keyword(s):  
Shear Zone ◽  
Volcanic Rocks ◽  
Sulfide Deposit ◽  
Ore Formation ◽  
Pillow Lavas ◽  
Bay Area ◽  
Internal Reaction ◽  
Sulfide Ore ◽  
Ore Minerals ◽  
Pressure Shadow

The Whalesback Mine is one of many copper deposits associated with Ordovician volcanic rocks in the Notre Dame Bay area, Newfoundland. The deposit consists of veins, pods, and disseminated sulfides localized within a highly chloritized shear zone cutting basaltic pillow lavas. Porphyritic dikes cut the shear zone, sulfide deposit, and the surrounding pillow lavas; all of the rocks, including the sulfide-rich rocks, have been regionally metamorphosed. Ore minerals, in decreasing order of abundance, include pyrite, chalcopyrite, pyrrhotite, sphalerite, mackinawite, pentlandite, magnetite, cubanite, galena, and ilmenite. Marcasite, covellite, and goethite are supergene minerals. Chlorite and quartz are the predominant gangue minerals. Muscovite, carbonates, sphene, albite, and epidote are minor constituents. Banding and streaking of sulfides in massive ores, crushed pyrite, and the local occurrence of pressure-shadow phenomena in the ore are indicative of shearing stress post-dating original sulfide ore formation. Present sulfide assemblages are compatible with relatively low temperatures and are the result of re-equilibration and internal reaction among the sulfides with decreasing temperature.

scholarly journals The Late-Paleoarchean Ultra-Depleted Commondale Komatiites: Earth's Hottest Lavas and Consequences for Eruption

2019 ◽  
Vol 60 (8) ◽  
pp. 1575-1620 ◽  
Author(s):  
Allan H Wilson
Keyword(s):  
High Temperature ◽  
Marginal Zone ◽  
Parental Magma ◽  
Mantle Peridotite ◽  
Rock Types ◽  
Low Viscosity ◽  
Incompatible Elements ◽  
Olivine Cumulates ◽  
Rare Category ◽  
Initial Source

Abstract The c.3·3 Ga Commondale komatiites located south of the Barberton greenstone belt in the Kaapvaal Craton are different from other komatiites, possessing compositional and textural features unique to this occurrence. Unlike almost all other known komatiite occurrences, they are not associated with komatiitic basalts or basalts. The komatiite flows are 0·5–25 m thick and are made up of a marginal zone of spinifex-textured and fine-grained aphyric rocks (low-Mg group) and an inner zone of olivine cumulates (high-Mg group), arranged in such a way to give highly symmetrical compositional profiles for many flows. Olivine is the dominant phase in all rocks, but orthopyroxene occurs as spinifex and elongate laths in the marginal zone. Clinopyroxene and plagioclase are entirely absent. The olivine cumulates formed from Mg-rich magma (36·1% MgO, 6·8% FeO) which caused inflation of the thicker flows. The maximum observed olivine composition in cores (Fo 96·6) is the highest recorded for any komatiite worldwide. The high-Mg magma would have erupted at a temperature close to 1670°C, the highest inferred temperature for an anhydrous terrestrial lava. The marginal zone is enriched in incompatible elements compared with the inner zone and formed by fractionation of the parental melt. However, all rock-types in the marginal zone are depleted in FeO (some as low as 3·5%) which could not have been derived by any primary magmatic process. The marginal zone rocks were modified by assimilation and/or alteration by seawater (or brine) components causing migration of iron and strong enrichment of sodium (up to 1·6 wt % Na2O) and chlorine (up to 2400 ppm). Zirconium has an identical distribution to sodium, with both elements greatly enriched above what would result from fractional crystallization, and may result from speciation of these elements at high temperature followed by post-crystallization alteration. Rare earth elements, Y and Nb have contents commensurate with fractionation of the primitive parental magma. Dendritic-textured olivine-rich rocks with orthopyroxene spinifex spatially and compositionally transitional between the marginal zone and the olivine cumulates resulted from interaction of the high temperature parental magma in the centre of the flows with the fractionated melt at the flow margins. A further manifestation of this association is the development of highly regular fine-scale (5–15 cm) layering (up to 45 layers) of alternating olivine cumulate and spinifex near the base of thick flows. This is overlain by olivine cumulates in which the melt/crystal-mush became arranged into a 3-dimensional network controlled by re-distribution of the trapped melt manifest by a spectacular knobbly texture in outcrop. Over 200 flow units are recognized and detailed chemical and mineralogical studies were carried out on drill cores intersecting 375 m of stratigraphy. The parental magma was highly depleted (in ppm Nb 0·017, Zr 1·18, total REE 1·7 and Gd/YbN=0·3, La/YbN=0·038) and although generally regarded to fall into the rare category of Al-enriched komatiites (AEKs), it is considered that these lavas are a unique class of their own of ultra-depleted komatiites. Relative to other AEKs the Commondale komatiites are both enriched in Al as well as being markedly depleted in Ti (390 ppm), giving rise to the extremely high Al2O3/TiO2 (81). The high temperature and low viscosity of the magma resulted in emplacement processes previously unrecognized in komatiites. The primary melt was derived by melting of mantle peridotite in equilibrium with olivine and orthopyroxene. The initial source was depleted in incompatible elements by small degrees of melting (3–4%) followed by high degrees of partial melting (70%) of the subsequent refractory source at 5 GPa (∼150 km).

Experimental determination of the phase relations of Pt and Pd antimonides and bismuthinides in the Fe-Ni-Cu sulfide systems between 1100 and 700 °C

2020 ◽  
Vol 105 (3) ◽  
pp. 344-352 ◽  
Author(s):  
Hassan M. Helmy ◽  
Roman Botcharnikov
Keyword(s):  
Solid Solution ◽  
Vapor Phase ◽  
Precious Metals ◽  
Immiscible Liquids ◽  
Monosulfide Solid Solution ◽  
Intermediate Solid Solution ◽  
Sulfide Melt ◽  
Last Stage ◽  
The Stability

Abstract The stability relations of Pt and Pd antimonides and bismuthinides in the Sb- and Bi-bearing Fe-Ni-Cu sulfide systems have been experimentally determined at temperatures between 1100 and 700 °C in evacuated silica tubes. Both PtSb and PdSb are stable as immiscible liquids at temperatures above 1100 and 1000 °C, respectively. The Fe-Ni-Cu-sulfide melt that coexists with the immiscible antimonide melt can dissolve up to 3.8 wt% Sb at 1100 °C, whereas monosulfide solid solution (mss) dissolves very low amounts of Sb over the entire 1100–700 °C temperature range. The liquidus of Pt-antimonides and Pdantimonides are above 980 and 750 °C, respectively. Bismuth does not form immiscible melt at 1100 °C but may partially partition into a vapor phase at 1050 °C. The Pt- and Pd-bismuthinides crystallize directly from immiscible bismuthinide melt only after crystallization of the sulfide melt into intermediate solid solution (iss). Insizwaite (PtBi2) and froodite (PdBi2) are stable at 780 and 700 °C, respectively. At the last stage of evolution of Sb-bearing magmatic Fe-Ni-Cu sulfide melts, Sb will form immiscible antimonide melt that will extract Pt and Pd from the sulfide melt. During cooling, Pt and Pd-antimonides will crystallize directly from the immiscible antimonide melt, and Pt-phases will form at higher temperatures relative to Pd-phases. Bismuth will partition into vapor phase and concentrate into a low-temperature melt in hydrothermal and porphyry systems that scavenge precious metals. The Sb and Bi (like Te) will be highly incompatible at moderate degrees of mantle partial melting.

Thallium geochemistry in the metamorphic Lengenbach sulfide deposit, Switzerland: Thallium-isotope fractionation in a sulfide melt

2014 ◽  
Vol 99 (4) ◽  
pp. 793-803 ◽  
Author(s):  
K. Hettmann ◽  
K. Kreissig ◽  
M. Rehkamper ◽  
T. Wenzel ◽  
R. Mertz-Kraus ◽  
...  
Keyword(s):  
Isotope Fractionation ◽  
Sulfide Deposit ◽  
Sulfide Melt

scholarly journals Interactions between feed system and process in production of preforms as linked micro parts

2018 ◽  
Vol 190 ◽  
pp. 15004 ◽  
Author(s):  
Philipp Wilhelmi ◽  
Christine Schattmann ◽  
Christian Schenck ◽  
Bernd Kuhfuss
Keyword(s):  
Laser Energy ◽  
Melting Process ◽  
Feed System ◽  
Output Rate ◽  
Cold Forming ◽  
Part Quality ◽  
Melt Pool ◽  
Multi Stage ◽  
Micro Parts ◽  
The Individual

This contribution deals with interactions between feed system and process in the production of preforms as linked parts, which is the first step of a multi-stage process chain for cold forming of micro parts. Due to the interconnection of the parts, the feed system is not only used for part transport, but also for the positioning during the generation of the preforms by laser rod melting. Thereby, the influence of the feed system on the production is more significant. Absorbed laser energy melts a wire, so that a melt pool is formed. While the wire is fixed on one side, the other side is fed into the melt pool whose volume increases. The production can be divided in the steps of preheating, active melting, solidification and transportation. The positioning takes place in parallel to the melting. Until now, the increase of the output rate was based especially on the consideration of the melting process and higher feed velocities. In this contribution, the interactions between feed and process are analyzed with the goal of further increasing the output rate. For that reason, the positioning behavior and its influence on the geometry of the produced preforms are analyzed. Finally, a method is presented, which unites the steps of transportation, preheating and melting. It is shown, that by a favorable coordination of the individual process steps, a further increase of the output rate is achievable without significantly worsening part quality.

scholarly journals Deposits of the Udokan-Chineysky ore-magmatic system of Eastern Siberia

2022 ◽  
Vol 962 (1) ◽  
pp. 012051
Author(s):  
B Gongalsky
Keyword(s):  
Sedimentary Rocks ◽  
Copper Deposit ◽  
Ore Deposits ◽  
Ultramafic Rocks ◽  
Limited Area ◽  
Terrigenous Rocks ◽  
Multi Stage ◽  
Sulfide Ore ◽  
Granite Rocks ◽  
Ore District

Abstract The aggregate of ore deposits localized in the Udokan-Chineysky ore district is unique and is the result of multi–stage, polygenetic formation. The deposits of copper and other metals formed at various depths occur within a limited area. The oxide and sulfide ore are spatially associated in the sedimentary rocks pertaining to the Paleoproterozoic Udokan Supergroup and the intrusive mafic–ultramafic rocks of the Chineysky Complex. The granite rocks of the Kodar Complex and gabbro rocks of the Chineysky Complex also date back to Paleoproterozoic. The same age has been established for metasomatic Nb–Ta–Zr–REE–Y and U mineralization in the albitized terrigenous rocks of the Udokan Supergroup (Katugin deposit and Chitkanda prospect) and U–Pd prospects hosted in terrigenous rocks. The U–REE mineralization superposed on the titanomagnetite deposits in the Chineysky pluton has not analogues in the world’s practice. The occurrences of uranium mineralization have been noted in form of pitchblende and U–Th rims around chalcopyrite grains at the Unkur copper deposit hosted in sedimentary rocks. The enrichment in U and Pb has been documented in crosscutting quartz veinlets with bornite mineralization at the Udokan deposit.

scholarly journals An intermittent detachment faulting system with a large sulfide deposit revealed by multi-scale magnetic surveys

2020 ◽  
Author(s):  
Tao Wu ◽  
Maurice Tivey ◽  
Chunhui Tao ◽  
Jinhui Zhang ◽  
Fei Zhou ◽  
...  
Keyword(s):  
Hydrothermal Activity ◽  
Southwest Indian Ridge ◽  
Sulfide Deposit ◽  
Magnetic Survey ◽  
Spreading Ridge ◽  
Hydrothermal Circulation ◽  
Crustal Accretion ◽  
Multi Scale ◽  
Multi Stage ◽  
Detachment Faulting

Abstract Magmatic and tectonic processes can contribute to discontinuous crustal accretion and play an important role in hydrothermal circulation at ultraslow-spreading ridges, however, it is difficult to accurately describe the processes without an age framework to constrain crustal evolution. Here we report on a multi-scale magnetic survey that provides constraints on the fine-scale evolution of a detachment faulting system that hosts hydrothermal activity at 49.7°E on the Southwest Indian Ridge. Reconstruction of the multi-stage detachment faulting history shows a previous episode of detachment faulting took place 0.76~1.48 My BP, while the present fault has been active for the past ~0.33 My just in the prime of life. This fault sustains hydrothermal circulation that has the potential for developing a large sulfide deposit. High resolution multiscale magnetics allows us to constrain the relative balance between periods of detachment faulting and magmatism to better describe accretionary processes on an ultraslow spreading ridge.

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