Structurally Controlled Cu-Zn-Pb-(Co) Mineralization in the Ombombo Subgroup, Kaokoland, Namibia

Allen, Nicole Kirsten; Hitzman, Murray W.; Sarg, J. F.; Ellmies, Rainer

doi:10.1130/abs/2016am-281527

Cited by 3 publications

(6 citation statements)

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“…Previous genetic models for the formation of these deposits have been the subject of debate and include VMS (e.g. Drobeck, 1981; Sheridan & Raymond, 1984a; Alers & Shallow, 1996; Shallow & Alers, 1996), carbonate-replacement skarn (e.g. Salotti, 1965), BHT (Zephyr Minerals Limited, 2018; ), and most recently, high-temperature fractionation of base and precious metals from peraluminous granitoids (Kleinhans & Swan, 2022).…”

Section: Introductionmentioning

confidence: 99%

The genesis of metamorphosed Paleoproterozoic massive sulphide occurrences in central Colorado: geological, mineralogical and sulphur isotope constraints

Berke,

Spry,

Heimann

et al. 2023

Geol. Mag.

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Paleoproterozoic massive Cu-Zn±Pb±Au±Ag sulphide deposits metamorphosed to the middle-upper amphibolite facies in central-south Colorado formed in a volcanic arc setting on the edge of the Yavapai crustal province. Previously published U-Pb ages on spatially related granitoids range from ∼1.9 to ∼1.1 Ga, while Pb isotope studies on galena from massive sulphides suggest mineralization formed at around 1.8–1.7 Ga. Some deposits in the Dawson-Green Mountain trend (DGMT) and the Gunnison belt are composed of Cu-Zn-Au-(Pb-Ag) mineralization that were overprinted by later Au-(Ag-Cu-Bi-Se-Te) mineralization. Sulphide mineralization is spatially related to amphibolite and bimodal, mafic-felsic volcanic rocks (gabbro, amphibolite, rhyolite and dacite) and granitoids, but it occurs mostly in biotite-garnet-quartz±sillimanite±cordierite schists and gneisses, spatially related to nodular sillimanite rocks, and in some locations, exhalative rocks (iron formations, gahnite-rich rocks and quartz-garnetite). The major metallic minerals of the massive sulphides include chalcopyrite, sphalerite, pyrite, pyrrhotite, and magnetite, with minor galena and gahnite. Altered rocks intimately associated with mineralization primarily consist of various amphiboles (gedrite, tremolite and hornblende), gahnite, biotite, garnet, cordierite, carbonate and rare högbomite. The Zn/Cd ratios of sphalerite (44 to 307) in deposits in the DGMT fall within the range of global volcanogenic massive sulphide (VMS) deposits but overlap with sphalerite from sedimentary exhalative (Sedex) deposits. Sulphur isotope values of sulphides (δ34S = −3.3 to +6.5) suggest sulphur was largely derived from magmatic sources, and that variations in isotopic values resulting from thermochemical sulphate reduction are due to small differences in physicochemical conditions. The preferred genetic model is for the deposits to be bimodal-mafic (Gunnison) to mafic-siliciclastic VMS deposits (Cotopaxi, Cinderella-Bon Ton, DGMT).

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Section: Introductionmentioning

confidence: 99%

The genesis of metamorphosed Paleoproterozoic massive sulphide occurrences in central Colorado: geological, mineralogical and sulphur isotope constraints

Berke,

Spry,

Heimann

et al. 2023

Geol. Mag.

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“…The Dolostone Ore Formation (DOF) mineralization is hosted in the Ombombo Subgroup of the Neoproterozoic Damara Supergroup (Allen, 2016). The Damara Supergroup sediments represent a succession from a rift basin to carbonate platform, starting with fluvial siliciclastics, grading into marine shales, siltstones, and carbonates.…”

Section: Regional Geologymentioning

confidence: 99%

“…The Damara Supergroup sediments represent a succession from a rift basin to carbonate platform, starting with fluvial siliciclastics, grading into marine shales, siltstones, and carbonates. The basal Nosib Group sediments were deposited in grabens formed during the break-up of Rodinia and are comprised of arkosic and felspathic sandstones with some interbedded conglomerates that uncomfortably overly the Paleoproterozoic basement (Guj, 1970;Porada, 1989;Miller, 2008;Allen, 2016). Overlying the Nosib Group is the Ombombo Subgroup, the basal member of the Otavi Group, composed of cyclical marine fine-grained siliciclastics and carbonates.…”

Section: Regional Geologymentioning

confidence: 99%

“…Overlying the Nosib Group is the Ombombo Subgroup, the basal member of the Otavi Group, composed of cyclical marine fine-grained siliciclastics and carbonates. Within the DOF area, the Ombombo Subgroup sediments are predominantly composed of calcareous shales and siltstones, interbedded with minor sandstones and carbonates (Hoffman and Halverson, 2008;Miller, 2008;Allen, 2016). The Ombombo Subgroup is overlain by the Abenab Subgroup, which in the DOF area is present as the Chuos Formation diamictite and Rasthof Formation cap-carbonates (Hoffmann and Prave, 1996;Hoffman, 2011;Allen, 2016).…”

Section: Regional Geologymentioning

confidence: 99%

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Sphalerite as a non-traditional critical metal source: Correlative microscopy (EPMA, EBSD, and APT) of cobalt-enriched sulfides from the sediment-hosted copper-cobalt Dolostone Ore Formation deposit, Namibia

et al. 2023

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Sphalerite from the sediment-hosted Dolostone Ore Formation (DOF) Cu-Co-Zn deposit, in northwestern Namibia, has previously been shown to contain extremely high concentrations of the critical metal Co (up to 1 wt%). These concentrations are the highest reported in sphalerite to date, and the how and why of sphalerite being able to incorporate such high concentrations of Co are poorly understood. We use correlative electron probe microanalysis, electron backscattered diffraction, and atom probe to reconstruct the likely incorporation mechanisms and modes of occurrence of such high Co concentrations in natural sphalerite. While over twenty samples were studied, the comprehensive analytical workflow was executed on one representative sample to gain a detailed understanding of Co enrichment. The sulfides of the studied sample are Co-rich pyrite, chalcopyrite, Co-rich sphalerite, linnaeite, cobaltpentlandite, and cobaltite, mentioned in order of abundance. Detailed petrography of these sulfides indicates that they formed through three stages during the main Cu-Co-Zn ore stage of the DOF. Cobalt was initially contained in pyrite that grew during Ore Stage 1 and was later affected by oxidizing fluids (Ore Stage two). This led to remobilization and growth of linnaeite (Co2+Co3+2S4). A later change in fO2 (Ore Stage three) led to the breakdown of linnaeite and the further growth of accessory cobaltite along with the Co-rich sphalerite and chalcopyrite. The hyper-enriched Co-sphalerite then is the last major sink for Co in the DOF deposit. A low Fe and Co and high Zn sub-grain boundary network within the Co-rich sphalerite was identified by EPMA and EBSD. This sub-grain network is believed to have formed during a later, secondary metamorphic stage (Cu-Zn (-Pb) Ore Stage 4), which developed during ductile deformational mineralization styles such as pressure shadows and veins. Our APT data reconstructions show no evidence for Co-inclusions within the Co-sphalerite, and spatial ion correlation analyses of the data suggest that Co occurs in the sphalerite through simple substitution of Zn. This study demonstrates that sphalerite may contain significant concentrations of the Co through simple substitution, potentially representing an important non-traditional Co source in future critical metal exploration.

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“…The glass microchannel was enclosed by a second blank using a calcium-assisted bonding technique. 54 The channel volume was approximately 41 μL.…”

Section: Channel Fabricationmentioning

confidence: 99%

Antibody Conjugate Assembly on Ultrasound-Confined Microcarrier Particles

Binkley

Cui

Berezin

et al. 2020

ACS Biomater. Sci. Eng.

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Bioconjugates are important next-generation drugs and imaging agents. Assembly of these increasingly complex constructs requires precise control over processing conditions, which is a challenge for conventional manual synthesis. This inadequacy has motivated the pursuit of new approaches for efficient, controlled modification of high-molecular-weight biologics such as proteins, carbohydrates, and nucleic acids. We report a novel, hands-free, semiautomated platform for synthetic manipulation of biomolecules using acoustically responsive microparticles as threedimensional reaction substrates. The microfluidic reactor incorporates a longitudinal acoustic trap that controls the chemical reactions within a localized acoustic field. Forces generated by this field immobilize the microscale substrates against the continuous flow of participating chemical reagents. Thus, the motion of substrates and reactants is decoupled, enabling exquisite control over multistep reaction conditions and providing high-yield, high-purity products with minimal user input. We demonstrate these capabilities by conjugating clinically relevant antibodies with a small molecule. The on-bead synthesis comprises capture of the antibody, coupling of a fluorescent tag, product purification, and product release. Successful capture and modification of a fluorescently labeled antibody are confirmed via fold increases of 49 and 11 in the green (antibody)-and red (small-molecule dye)-channel median intensities determined using flow cytometry. Antibody conjugates assembled on acoustically responsive, ultrasound-confined microparticles exhibit similar quality and quantity to those prepared manually by a skilled technician.

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Structurally Controlled Cu-Zn-Pb-(Co) Mineralization in the Ombombo Subgroup, Kaokoland, Namibia

Cited by 3 publications

References 0 publications

The genesis of metamorphosed Paleoproterozoic massive sulphide occurrences in central Colorado: geological, mineralogical and sulphur isotope constraints

The genesis of metamorphosed Paleoproterozoic massive sulphide occurrences in central Colorado: geological, mineralogical and sulphur isotope constraints

Sphalerite as a non-traditional critical metal source: Correlative microscopy (EPMA, EBSD, and APT) of cobalt-enriched sulfides from the sediment-hosted copper-cobalt Dolostone Ore Formation deposit, Namibia

Antibody Conjugate Assembly on Ultrasound-Confined Microcarrier Particles

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