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Franco Pirajno

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Franco Pirajno, has considerable experience in tectonics, ore deposit geology and mineral exploration in Europe, southern Africa, South East Asia, New Zealand, Indonesia, the southwest Pacific, China, Greenland, southern and eastern Siberia and Australia. While working at the GSWA his duties included in-depth studies of mineral systems of Western Australia and comparative analyses with similar systems in other parts of the world

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Papers by Franco Pirajno

Chert in the Palaeoproterozoic Bartle Member, Killara Formation, Yerrida Basin, Western Australia: a rift-related playa lake and thermal spring environment?

Precambrian Research, 2002

Palaeoproterozoic chert in the Bartle Member of the Killara Formation, Yerrida Group, Yerrida Bas... more Palaeoproterozoic chert in the Bartle Member of the Killara Formation, Yerrida Group, Yerrida Basin of Western Australia, contains an anomalous association of crystal structures and rock fabrics that are difficult to interpret. The association appears to indicate an evaporitic-pyroclastic-thermal-spring environment associated with rifting at about 2.2 Ga. The chert member contains silica pseudomorphs after evaporite minerals that in places enclose relict isolated crystals and aggregates of crystals of gypsum and anhydrite. The evaporite minerals are associated with minerals such as barite and analcime. The association of these minerals, together with palaeoenvironmental evidence, invites comparison with rocks of the Afar region and Lake Magadi in the East African Rift System. The Bartle Member locally contains anomalous gold (up to twelve times the average crustal values of 4 ppb) and barium. It also contains finely disseminated kerogen together with numerous spheroids (classified here as microdubiofossils) and some curious structures showing organisation into complex petal-like structures (classified here as putative microfossils). The Bartle Member chert has many characteristics of playa lake and thermal-spring deposits, and may host epithermal precious-metal mineralisation.

State of the art: Italian carbonatites and their potential for critical-metal deposits

Gondwana Research, Sep 1, 2016

This paper is an updated overview, including many new data, of what is known about Italian alkali... more This paper is an updated overview, including many new data, of what is known about Italian alkaline-carbonatite complexes, plus a new description of a carbothermal residua-related district, and their potential for mineral deposits. The Italian carbonatite occurrences can be divided into two belts. The first is a 350 km long and 75 km wide belt along the Apennines mountain range mainly with primary extrusive carbonatites generally from monogenic volcanoes and from the Vulture volcanic complex; the second belt is 60 km long and 20 km wide in the Northern Latium region in which are carbothermal residua carbonatites and fluorite mineralisation deposited by hightemperature fluids rich in CO 2 , SO 2 and fluorine occurring in caldera volcanoes. Several of the raw materials identified as critical as well as other commodities, occur in Italian carbonatites and alkaline rocks, such as Light Rare Earth Elements, vanadium, niobium, zirconium, fluorite and phosphate. At the Pianciano quarry (Bracciano) fluorite-rich ore (fluor-ore, = fluorite in a mineralised gangue) is actually exploited as flux for cement, but Rare Earth Elements (+V) could be a notable by-product (300,000 metric tonnes, equivalent to 4.2% of European resources). Pyrochlore, monazite, apatite, britholite bearing subvolcanic rocks in ejecta from the Vulture volcano are of a near-economic grade, but their geological constraints are not known. A conceptual

Geological Processes and Hydrothermal Mineralisation in Plate Tectonic Settings — Mineral Exploration

Springer eBooks, 1992

The Earth’s outer layers, namely, the lithosphere and the asthenosphere have an important role in... more The Earth’s outer layers, namely, the lithosphere and the asthenosphere have an important role in the mechanisms of plate tectonics. The outermost layer of our planet is the relatively strong and rigid lithosphere — about 100 km thick — broken up into a number of major and minor plates, whose present-day configuration is shown in Fig. 6.1. The boundaries between plates, divergent (rifting, spreading zones), convergent (subduction and collision zones) and transform faults, are the sites of intense geological activity including earthquakes, volcanism, mountain building and of course mineralisation. The lithosphere overlies the asthenosphere, a weak region of the upper mantle about 200 km thick, where temperatures approach melting point. The boundary, which is probably gradational, between these two layers is by no means well defined, and is not to be confused with the crust-mantle boundary which is defined by the Mohorovicic discontinuity. Although the reason for the movement of the lithospheric plates is not entirely understood, it is generally agreed that mantle convective motions, possibly driven by radiogenic heat, may be responsible. The spreading motion of the oceanic crust is indicated by the characteristic magnetic stripes, symmetrically disposed on either side of a mid-ocean ridge, and first described by Vine and Matthews (1963). In this chapter we examine plate tectonic settings and associated types of hydrothermal mineralisation. A schematic view of plate tectonic settings is shown in Fig. 6.2.

Crustal Evolution, Global Tectonics and Mineral Deposits

Springer eBooks, 1992

The theory of sea-floor spreading and the “new” global tectonics, including the more recent ideas... more The theory of sea-floor spreading and the “new” global tectonics, including the more recent ideas on accretionary tectonics, has permitted a much clearer understanding of the genesis of mineral deposits. This understanding is essentially provided by a unifying framework within which processes of ore genesis can be integrated. In this way mineralisation types can be related to time-space positions, in specific lithospheric plate settings, and within continuously evolving crustal geodynamic patterns. The spatial distribution of mineral deposits as related to plate tectonic processes has been widely discussed in many papers, especially during the 1970–1980 decade. Consequently, excellent textbooks on the topic were published soon after, which in spite of subsequent advances in more recent years, remain important texts for providing the geologist with an essential background in the study of mineral deposits. The books referred to are those published by Mitchell and Garson (1981), Hutchison (1983) and Sawkins (1990). Equally important in models of ore genesis is an understanding of the evolutionary trends of mineral deposits through the geological ages. This field of study is obviously connected with the evolution of plate configurations and their interactions through time. The works of Watson (1973,1978), Reed and Watson (1975), Cloud (1976), Goodwin (1981), Lambert and Groves (1981), Meyer (1981, 1988), Hutchinson (1980), and Windley (1984) all deal with these evolutionary trends.

$Research paper thumbnail of Magnesium isotope fractionation in differentiation of mafic-alkaline-carbonatitic magma and Fe-P-REE-rich melt at Bayan Obo, China$

Magnesium isotope fractionation in differentiation of mafic-alkaline-carbonatitic magma and Fe-P-REE-rich melt at Bayan Obo, China

Ore Geology Reviews

Corrigendum to “Types of carbonatites: Geochemistry, genesis and mantle sources” [Lithos 386–387 (2021) 105982]

Lithos

The evolution from plate margin to intraplate mineral systems in the Capricorn Orogen, links to prospectivity

Ore Geology Reviews

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

The Ore-Forming Fluid Nature, Source, and Evolution of the Dunbasitao Gold Deposit, East Junggar, China: Constraints from Geology, Fluid Inclusions, and C-H-O Isotopes

SSRN Electronic Journal

Metallogeny of the Southern Altaids: Key to understanding the accretionary tectonics and crustal evolution of Central Asia

Ore Geology Reviews

Abiotic anoxic iron oxidation, formation of Archean banded iron formations, and the oxidation of early Earth

Earth and Planetary Science Letters, 2022

Iron in the early anoxic oceans of Archean age (4000-2500 million years ago) is believed to have ... more Iron in the early anoxic oceans of Archean age (4000-2500 million years ago) is believed to have been oxidized to form banded iron formations (BIF). Previously, it has been proposed that iron was oxidized either by free oxygen, H2O2, microbial oxidation, or photo-oxidation. However, these mechanisms are difficult to reconcile with evidence for the oceans at that time having been largely devoid of dissolved oxygen and oxidants, together with the rarity of microbial remains in BIF and restrictively slow rates of photo-oxidation. Experiments reported here show that 2 ferrous iron readily oxidizes in analogs of Archean anoxic seawater following the precipitation of ferrous hydroxide. Once precipitated, ferrous hydroxide undergoes decomposition to elemental iron that reacts with water at room temperature to form ferric iron and release hydrogen gas. The ferric iron may then be incorporated into green rust, a mixed ferrous-ferric phase that ages into iron minerals commonly found in BIF. Our finding suggests that anoxic iron oxidation may have contributed to the formation of oxide-facies BIF, especially Algoma-type BIF that likely formed in semirestricted basins where ferrous hydroxide saturation was more easily achieved. Additionally, ferrous hydroxide decomposition would have contributed to early Earth's oxidation, as a result of hydrogen escape to space, thus providing new insights into environmental and biological conditions on early Earth.

Mineralogical and Geochemical Peculiarities and PT Conditions of Ores from the Kyzyl-Tashtyg VMS polymetallic deposit, Eastern Tuva: Fluid Inclusion and S, O, C Isotopic data

Ore Geology Reviews, 2022

Metamorphic Hydrothermal (Orogenic-Type) Systems

Modern Approaches in Solid Earth Sciences, 2022

Geology of the Fairbairn 1:100 000 sheet

Fluid-rock reactions of the Triassic Taiyangshan porphyry Cu-Mo deposit (West Qinling, China) constrained by QEMSCAN and iron isotope

Ore Geology Reviews, 2021

Abstract The multiphase hydrothermal superposition phenomena on porphyry deposits, the mineral co... more Abstract The multiphase hydrothermal superposition phenomena on porphyry deposits, the mineral complexity and characteristics of the alteration-associated assemblages limit the further determination for the magmatic-hydrothermal evolution in porphyry deposits. The Taiyangshan porphyry Cu-Mo deposit in the northern margin of the Triassic West Qinling orogenic belt exhibits a multi-stage, alteration-related quartz sulfide veins that recorded element migration processes during fluid-rock reactions. In this study, we investigated hydrothermal veins in the Taiyangshan deposit focusing on vein compositions and structures as well as the evolution of ore formation using quantitative evaluation of minerals by scanning electron microscopy (QEMSCAN) and iron isotope analyses. The formation of the early K-feldspar-biotite-quartz-magnetite-apatite veins is closely associated with the early potassic alteration, and during the fluid-rock reactions, Si, S, Fe, and K migrated in, while Mg, Ca and Na migrated out. K-feldspar-chlorite-pyrite-chalcopyrite-quartz veins correlated to the propylitic alteration, dominantly caused the migration of Si, Fe, S, Ca Mg, Al and K. Quartz-sericite-pyrite veins corresponding to the phyllic alteration processes that occurred in a relatively late stage, during the fluid-rock reactions of which, Si, Fe, S, and K migrated into the system. The δ56Fe whole-rock values of altered porphyries range from 0.08 ‰ to 0.31 ‰, and δ56Fe values of pyrite from quartz veins range from 0.30 ‰ to 0.57 ‰. Iron isotope compositions of both pyrites of the ore-bearing wall rocks and the quartz-sulfide veins of the Taiyangshan Cu-Mo deposit are generally uniform, which indicate the same source origin between the ore-bearing porphyry and the iron isotope compositions of the metal sulfide in the quartz veins, and additionally highlights that the ore-forming source is closely related to the ore-bearing porphyry. Magnetite precipitated in the early stage of potassic alteration, resulting in the enrichment of the light Fe isotope in the early fluids. Crystallization and precipitation of pyrite mainly occurred during processes of propylitic and phyllic alteration, leading to an absorption of the light Fe isotope, and elsewhere, an enrichment of the heavy Fe isotope in the fluids. During the fluid-rock reactions of propylitic and phyllic alteration, a large amount of S migrated into the veins, thereby promoting the fractionation of Fe isotope. Moreover, the development of the ore-forming fluids enriched with heavy Fe isotope from early potassic- to late phyllic alteration, are indicative of isotopic progressions from the early lithostatic pressure to the late hydrostatic pressure. Our current research on the Taiyangshan Cu-Mo porphyry deposit helps to explain the evolutionary processes of the magmatic–hydrothermal system, and also improves our understanding of a porphyry metallogenic evolution model.

Cycles of hydrothermal activity, precipitation of chemical sediments, with special reference to Algoma-type BIF

Gondwana Research, 2021

Abstract In this contribution, we present the more or less consistent banding (mm to several cm) ... more Abstract In this contribution, we present the more or less consistent banding (mm to several cm) from Fe-rich to silica-rich chemical sediments associated with the venting that leads to the formation of banded sediments in several hydrothermal mineral systems, such as volcanogenic massive sulphides (VMS) and sedimentary exhalative (SEDEX) deposits. However, in this contribution we specifically refer to the banded sediments that are commonly known as Algoma-type iron formation (BIF). Algoma-type BIF does provide a somewhat unusual and poorly investigated case of chemical sediments banding. The banding of these chemical sediments in terms of Fe oxides and silica is related to their alternate dominance in the upwelling fluids in a variety of settings ranging from a sea floor spreading centre to continental rift-related settings. Equally important is the concept that Algoma-type BIF may well be associated with and a distal expression of sulphide-bearing mineral systems.

Bushveld superplume drove Proterozoic magmatism and metallogenesis in Australia

Scientific Reports, 2020

Large-scale mantle convective processes are commonly reflected in the emplacement of Large Igneou... more Large-scale mantle convective processes are commonly reflected in the emplacement of Large Igneous Provinces (LIPs). These are high-volume, short-duration magmatic events consisting mainly of extensive flood basalts and their associated plumbing systems. One of the most voluminous LIPs in the geological record is the ~ 2.06 billion-year-old Bushveld Igneous Complex of South Africa (BIC), one of the most mineralised magmatic complexes on Earth. Surprisingly, the known geographic envelope of magmatism related to the BIC is limited to a series of satellite intrusions in southern Africa and has not been traced further afield. This appears inconsistent with the inferred large size of the BIC event. Here, we present new radiometric ages for alkaline magmatism in the Archean Yilgarn Craton (Western Australia), which overlap the emplacement age of the BIC and indicate a much more extensive geographic footprint of the BIC magmatic event. To assess plume involvement at this distance, we prese...

Minimal biomass deposition in banded iron formations inferred from organic matter and clay relationships

Nature Communications, 2019

The cycling of iron and organic matter (OM) is thought to have been a major biogeochemical cycle ... more The cycling of iron and organic matter (OM) is thought to have been a major biogeochemical cycle in the early ferruginous oceans which contributed to the deposition of banded iron formations (BIF). However, BIF are deficient in OM, which is postulated to be the result of near-complete oxidation of OM during iron reduction. We test this idea by documenting the prevalence of OM in clays within BIF and clays in shales associated with BIF. We find in shales >80% of OM occurs in clays, but <1% occurs in clays within BIF. Instead, in BIF OM occurs with 13C-depleted carbonate and apatite, implying OM oxidation occurred. Conversely, BIF which possess primary clays would be expected to preserve OM in clays, yet this is not seen. This implies OM deposition in silicate-bearing BIF would have been minimal, this consequently stifled iron-cycling and primary productivity through the retention of nutrients in the sediments.

Abstracts from the 2017–2018 Mineral Deposits Studies Group meeting

Applied Earth Science, 2018

Cobalt in the Congolese Copperbelt mines is commonly recovered from Co-oxi-hydroxides (i.e. heter... more Cobalt in the Congolese Copperbelt mines is commonly recovered from Co-oxi-hydroxides (i.e. heterogenite, asbolane) by acid-leaching under reducing conditions. However, most operations face a limit in the leaching yields of cobalt, which usually do not exceed 80%. The main aim of this work was to investigate the causes of the poor recovery, in order to reconcile the Co recovery with processing techniques. Several concentrate samples from different mine plants of Katanga Copperbelt (Kalukuluku, Mutanda, Mabaya, Kamwali and Fungurume) were selected and subjected to a full mineralogical characterisation by Optical Microscopy (OM), X-Ray Diffraction (XRD), automated mineralogy and Scanning Electron Microscopy by Energy Dispersive Spectroscopy (SEM-EDS) prior and after leaching tests. OM and XRD results were used as background information to build a mineral list for mineral identification during automated mineralogy analyses by Mineralogic Mining System (Zeiss ltd.). Automated mineralogy allowed obtaining mineral maps, modal mineralogy, chemical assays and Co deportment for each specimen prior and after leaching. Mineral maps of the leached samples were useful to observe the occurrences of poorly leached Co-bearing particles which were further investigated by SEM-EDS and X-mapping. The results showed that heterogenite (rarely associated with asbolane) is the main cobalt mineral in Katanga. Mineralogic Mining System was able to discriminate between pure heterogenite, and Si-Al-K-bearing heterogenite, asbolane/heterogenite, Heterogenite+Fe-oxi-hydroxide and Co-bearing mixed phases, which resulted more refractory to leaching. The comparison between modal mineralogy of pre-and post-leached samples indicates a decrease, but not a full leaching of these Co phases: chemical assays and Codeportment, in fact, still reveal the presence of low Co% within Co phases listed above (Table 1). SEM-EDS and Xmapping on single particles of some specimens corroborated the results obtained by Mineralogic.

New evidence from the Wuliji'Oboo fluorite deposit for the role of the paleo‐Pacific Plate and Mongol–Okhotsk suture in creating extensive fluorite mineralization in the Great Xing'an Range, NE China

Geological Journal, 2019

The Wuliji'Oboo fluorite deposit is a newly discovered deposit hosted by volcanic rocks of the Ea... more The Wuliji'Oboo fluorite deposit is a newly discovered deposit hosted by volcanic rocks of the Early Cretaceous Baiyin'gaolao Formation, which are located in the Great Xing'an Range. Fluorite orebodies within this area are controlled by the NNE-trending faults. The ΣREE of fluorite samples ranges from 19.18 to 361.22 ppm, with an average of 131.14 ppm. The homogenization temperatures are concentrated in the ranges of 100-150°C and 230-350°C, while the salinity is concentrated in 0.3-1.0 and 2.0-4.5 wt.% NaCl eqv., and the density has ranges of 0.92-0.96 and 0.75-0.8 g/cm 3 , respectively. The δD V-SMOW values of fluid inclusions within the fluorite range between −122.3‰ and −105.6‰ with a mean of −115.36‰. The δ 18 O V-SMOW of fluorite ranges from −12.0 to −8.5‰, average is −9.9‰. Sm-Nd isotopic data on the fluorite ore yield an isochron age of 122 ± 15 Ma and have ɛ Nd (t) values ranging from +3.15 to +4.16 and (87 Sr/ 86 Sr) i values ranging from 0.704907 to 0.705765. In this contribution, field, petrologic, and geochemical data lead us to the following salient findings: (a) The ore consists of fluorite, quartz, and calcite, with host rock alteration that includes silicification, calcitization, and sericitization. The major element data reveal that the host rocks are a series of highK calc-alkaline rhyolite. The REEs suggest that F-rich fluids in this region might have experienced a longdistance migration. The Tb/Ca-Tb/La diagram confirms a hydrothermal origin for the deposit. (b) Petrographic evidence and fluid inclusions in the fluorites indicate that this deposit might have two ore-forming stages. The ore-forming fluids can be attributed to a NaCl-H 2 OF system with moderate-low temperature, low salinity, and low density and have a meteoric water source, with water/rock reaction as the main mechanism for fluorite precipitation. (c) The deposit was formed in an anorogenic within-plate extensional tectonic setting related to the lithospheric thinning occurring after the Mongolian-Okhotsk Ocean closure.

Asteroids Impacts, Crustal Evolution and Related Mineral Systems with Special Reference to Australia

Modern Approaches in Solid Earth Sciences, 2018

The use of general descriptive names, registered names, trademarks, service marks, etc. in this p... more The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Chert in the Palaeoproterozoic Bartle Member, Killara Formation, Yerrida Basin, Western Australia: a rift-related playa lake and thermal spring environment?

Precambrian Research, 2002

Palaeoproterozoic chert in the Bartle Member of the Killara Formation, Yerrida Group, Yerrida Bas... more Palaeoproterozoic chert in the Bartle Member of the Killara Formation, Yerrida Group, Yerrida Basin of Western Australia, contains an anomalous association of crystal structures and rock fabrics that are difficult to interpret. The association appears to indicate an evaporitic-pyroclastic-thermal-spring environment associated with rifting at about 2.2 Ga. The chert member contains silica pseudomorphs after evaporite minerals that in places enclose relict isolated crystals and aggregates of crystals of gypsum and anhydrite. The evaporite minerals are associated with minerals such as barite and analcime. The association of these minerals, together with palaeoenvironmental evidence, invites comparison with rocks of the Afar region and Lake Magadi in the East African Rift System. The Bartle Member locally contains anomalous gold (up to twelve times the average crustal values of 4 ppb) and barium. It also contains finely disseminated kerogen together with numerous spheroids (classified here as microdubiofossils) and some curious structures showing organisation into complex petal-like structures (classified here as putative microfossils). The Bartle Member chert has many characteristics of playa lake and thermal-spring deposits, and may host epithermal precious-metal mineralisation.

State of the art: Italian carbonatites and their potential for critical-metal deposits

Gondwana Research, Sep 1, 2016

This paper is an updated overview, including many new data, of what is known about Italian alkali... more This paper is an updated overview, including many new data, of what is known about Italian alkaline-carbonatite complexes, plus a new description of a carbothermal residua-related district, and their potential for mineral deposits. The Italian carbonatite occurrences can be divided into two belts. The first is a 350 km long and 75 km wide belt along the Apennines mountain range mainly with primary extrusive carbonatites generally from monogenic volcanoes and from the Vulture volcanic complex; the second belt is 60 km long and 20 km wide in the Northern Latium region in which are carbothermal residua carbonatites and fluorite mineralisation deposited by hightemperature fluids rich in CO 2 , SO 2 and fluorine occurring in caldera volcanoes. Several of the raw materials identified as critical as well as other commodities, occur in Italian carbonatites and alkaline rocks, such as Light Rare Earth Elements, vanadium, niobium, zirconium, fluorite and phosphate. At the Pianciano quarry (Bracciano) fluorite-rich ore (fluor-ore, = fluorite in a mineralised gangue) is actually exploited as flux for cement, but Rare Earth Elements (+V) could be a notable by-product (300,000 metric tonnes, equivalent to 4.2% of European resources). Pyrochlore, monazite, apatite, britholite bearing subvolcanic rocks in ejecta from the Vulture volcano are of a near-economic grade, but their geological constraints are not known. A conceptual

Geological Processes and Hydrothermal Mineralisation in Plate Tectonic Settings — Mineral Exploration

Springer eBooks, 1992

The Earth’s outer layers, namely, the lithosphere and the asthenosphere have an important role in... more The Earth’s outer layers, namely, the lithosphere and the asthenosphere have an important role in the mechanisms of plate tectonics. The outermost layer of our planet is the relatively strong and rigid lithosphere — about 100 km thick — broken up into a number of major and minor plates, whose present-day configuration is shown in Fig. 6.1. The boundaries between plates, divergent (rifting, spreading zones), convergent (subduction and collision zones) and transform faults, are the sites of intense geological activity including earthquakes, volcanism, mountain building and of course mineralisation. The lithosphere overlies the asthenosphere, a weak region of the upper mantle about 200 km thick, where temperatures approach melting point. The boundary, which is probably gradational, between these two layers is by no means well defined, and is not to be confused with the crust-mantle boundary which is defined by the Mohorovicic discontinuity. Although the reason for the movement of the lithospheric plates is not entirely understood, it is generally agreed that mantle convective motions, possibly driven by radiogenic heat, may be responsible. The spreading motion of the oceanic crust is indicated by the characteristic magnetic stripes, symmetrically disposed on either side of a mid-ocean ridge, and first described by Vine and Matthews (1963). In this chapter we examine plate tectonic settings and associated types of hydrothermal mineralisation. A schematic view of plate tectonic settings is shown in Fig. 6.2.

Crustal Evolution, Global Tectonics and Mineral Deposits

Springer eBooks, 1992

The theory of sea-floor spreading and the “new” global tectonics, including the more recent ideas... more The theory of sea-floor spreading and the “new” global tectonics, including the more recent ideas on accretionary tectonics, has permitted a much clearer understanding of the genesis of mineral deposits. This understanding is essentially provided by a unifying framework within which processes of ore genesis can be integrated. In this way mineralisation types can be related to time-space positions, in specific lithospheric plate settings, and within continuously evolving crustal geodynamic patterns. The spatial distribution of mineral deposits as related to plate tectonic processes has been widely discussed in many papers, especially during the 1970–1980 decade. Consequently, excellent textbooks on the topic were published soon after, which in spite of subsequent advances in more recent years, remain important texts for providing the geologist with an essential background in the study of mineral deposits. The books referred to are those published by Mitchell and Garson (1981), Hutchison (1983) and Sawkins (1990). Equally important in models of ore genesis is an understanding of the evolutionary trends of mineral deposits through the geological ages. This field of study is obviously connected with the evolution of plate configurations and their interactions through time. The works of Watson (1973,1978), Reed and Watson (1975), Cloud (1976), Goodwin (1981), Lambert and Groves (1981), Meyer (1981, 1988), Hutchinson (1980), and Windley (1984) all deal with these evolutionary trends.

$Research paper thumbnail of Magnesium isotope fractionation in differentiation of mafic-alkaline-carbonatitic magma and Fe-P-REE-rich melt at Bayan Obo, China$

Magnesium isotope fractionation in differentiation of mafic-alkaline-carbonatitic magma and Fe-P-REE-rich melt at Bayan Obo, China

Ore Geology Reviews

Corrigendum to “Types of carbonatites: Geochemistry, genesis and mantle sources” [Lithos 386–387 (2021) 105982]

Lithos

The evolution from plate margin to intraplate mineral systems in the Capricorn Orogen, links to prospectivity

Ore Geology Reviews

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

The Ore-Forming Fluid Nature, Source, and Evolution of the Dunbasitao Gold Deposit, East Junggar, China: Constraints from Geology, Fluid Inclusions, and C-H-O Isotopes

SSRN Electronic Journal

Metallogeny of the Southern Altaids: Key to understanding the accretionary tectonics and crustal evolution of Central Asia

Ore Geology Reviews

Abiotic anoxic iron oxidation, formation of Archean banded iron formations, and the oxidation of early Earth

Earth and Planetary Science Letters, 2022

Iron in the early anoxic oceans of Archean age (4000-2500 million years ago) is believed to have ... more Iron in the early anoxic oceans of Archean age (4000-2500 million years ago) is believed to have been oxidized to form banded iron formations (BIF). Previously, it has been proposed that iron was oxidized either by free oxygen, H2O2, microbial oxidation, or photo-oxidation. However, these mechanisms are difficult to reconcile with evidence for the oceans at that time having been largely devoid of dissolved oxygen and oxidants, together with the rarity of microbial remains in BIF and restrictively slow rates of photo-oxidation. Experiments reported here show that 2 ferrous iron readily oxidizes in analogs of Archean anoxic seawater following the precipitation of ferrous hydroxide. Once precipitated, ferrous hydroxide undergoes decomposition to elemental iron that reacts with water at room temperature to form ferric iron and release hydrogen gas. The ferric iron may then be incorporated into green rust, a mixed ferrous-ferric phase that ages into iron minerals commonly found in BIF. Our finding suggests that anoxic iron oxidation may have contributed to the formation of oxide-facies BIF, especially Algoma-type BIF that likely formed in semirestricted basins where ferrous hydroxide saturation was more easily achieved. Additionally, ferrous hydroxide decomposition would have contributed to early Earth's oxidation, as a result of hydrogen escape to space, thus providing new insights into environmental and biological conditions on early Earth.

Mineralogical and Geochemical Peculiarities and PT Conditions of Ores from the Kyzyl-Tashtyg VMS polymetallic deposit, Eastern Tuva: Fluid Inclusion and S, O, C Isotopic data

Ore Geology Reviews, 2022

Metamorphic Hydrothermal (Orogenic-Type) Systems

Modern Approaches in Solid Earth Sciences, 2022

Geology of the Fairbairn 1:100 000 sheet

Fluid-rock reactions of the Triassic Taiyangshan porphyry Cu-Mo deposit (West Qinling, China) constrained by QEMSCAN and iron isotope

Ore Geology Reviews, 2021

Abstract The multiphase hydrothermal superposition phenomena on porphyry deposits, the mineral co... more Abstract The multiphase hydrothermal superposition phenomena on porphyry deposits, the mineral complexity and characteristics of the alteration-associated assemblages limit the further determination for the magmatic-hydrothermal evolution in porphyry deposits. The Taiyangshan porphyry Cu-Mo deposit in the northern margin of the Triassic West Qinling orogenic belt exhibits a multi-stage, alteration-related quartz sulfide veins that recorded element migration processes during fluid-rock reactions. In this study, we investigated hydrothermal veins in the Taiyangshan deposit focusing on vein compositions and structures as well as the evolution of ore formation using quantitative evaluation of minerals by scanning electron microscopy (QEMSCAN) and iron isotope analyses. The formation of the early K-feldspar-biotite-quartz-magnetite-apatite veins is closely associated with the early potassic alteration, and during the fluid-rock reactions, Si, S, Fe, and K migrated in, while Mg, Ca and Na migrated out. K-feldspar-chlorite-pyrite-chalcopyrite-quartz veins correlated to the propylitic alteration, dominantly caused the migration of Si, Fe, S, Ca Mg, Al and K. Quartz-sericite-pyrite veins corresponding to the phyllic alteration processes that occurred in a relatively late stage, during the fluid-rock reactions of which, Si, Fe, S, and K migrated into the system. The δ56Fe whole-rock values of altered porphyries range from 0.08 ‰ to 0.31 ‰, and δ56Fe values of pyrite from quartz veins range from 0.30 ‰ to 0.57 ‰. Iron isotope compositions of both pyrites of the ore-bearing wall rocks and the quartz-sulfide veins of the Taiyangshan Cu-Mo deposit are generally uniform, which indicate the same source origin between the ore-bearing porphyry and the iron isotope compositions of the metal sulfide in the quartz veins, and additionally highlights that the ore-forming source is closely related to the ore-bearing porphyry. Magnetite precipitated in the early stage of potassic alteration, resulting in the enrichment of the light Fe isotope in the early fluids. Crystallization and precipitation of pyrite mainly occurred during processes of propylitic and phyllic alteration, leading to an absorption of the light Fe isotope, and elsewhere, an enrichment of the heavy Fe isotope in the fluids. During the fluid-rock reactions of propylitic and phyllic alteration, a large amount of S migrated into the veins, thereby promoting the fractionation of Fe isotope. Moreover, the development of the ore-forming fluids enriched with heavy Fe isotope from early potassic- to late phyllic alteration, are indicative of isotopic progressions from the early lithostatic pressure to the late hydrostatic pressure. Our current research on the Taiyangshan Cu-Mo porphyry deposit helps to explain the evolutionary processes of the magmatic–hydrothermal system, and also improves our understanding of a porphyry metallogenic evolution model.

Cycles of hydrothermal activity, precipitation of chemical sediments, with special reference to Algoma-type BIF

Gondwana Research, 2021

Abstract In this contribution, we present the more or less consistent banding (mm to several cm) ... more Abstract In this contribution, we present the more or less consistent banding (mm to several cm) from Fe-rich to silica-rich chemical sediments associated with the venting that leads to the formation of banded sediments in several hydrothermal mineral systems, such as volcanogenic massive sulphides (VMS) and sedimentary exhalative (SEDEX) deposits. However, in this contribution we specifically refer to the banded sediments that are commonly known as Algoma-type iron formation (BIF). Algoma-type BIF does provide a somewhat unusual and poorly investigated case of chemical sediments banding. The banding of these chemical sediments in terms of Fe oxides and silica is related to their alternate dominance in the upwelling fluids in a variety of settings ranging from a sea floor spreading centre to continental rift-related settings. Equally important is the concept that Algoma-type BIF may well be associated with and a distal expression of sulphide-bearing mineral systems.

Bushveld superplume drove Proterozoic magmatism and metallogenesis in Australia

Scientific Reports, 2020

Large-scale mantle convective processes are commonly reflected in the emplacement of Large Igneou... more Large-scale mantle convective processes are commonly reflected in the emplacement of Large Igneous Provinces (LIPs). These are high-volume, short-duration magmatic events consisting mainly of extensive flood basalts and their associated plumbing systems. One of the most voluminous LIPs in the geological record is the ~ 2.06 billion-year-old Bushveld Igneous Complex of South Africa (BIC), one of the most mineralised magmatic complexes on Earth. Surprisingly, the known geographic envelope of magmatism related to the BIC is limited to a series of satellite intrusions in southern Africa and has not been traced further afield. This appears inconsistent with the inferred large size of the BIC event. Here, we present new radiometric ages for alkaline magmatism in the Archean Yilgarn Craton (Western Australia), which overlap the emplacement age of the BIC and indicate a much more extensive geographic footprint of the BIC magmatic event. To assess plume involvement at this distance, we prese...

Minimal biomass deposition in banded iron formations inferred from organic matter and clay relationships

Nature Communications, 2019

The cycling of iron and organic matter (OM) is thought to have been a major biogeochemical cycle ... more The cycling of iron and organic matter (OM) is thought to have been a major biogeochemical cycle in the early ferruginous oceans which contributed to the deposition of banded iron formations (BIF). However, BIF are deficient in OM, which is postulated to be the result of near-complete oxidation of OM during iron reduction. We test this idea by documenting the prevalence of OM in clays within BIF and clays in shales associated with BIF. We find in shales >80% of OM occurs in clays, but <1% occurs in clays within BIF. Instead, in BIF OM occurs with 13C-depleted carbonate and apatite, implying OM oxidation occurred. Conversely, BIF which possess primary clays would be expected to preserve OM in clays, yet this is not seen. This implies OM deposition in silicate-bearing BIF would have been minimal, this consequently stifled iron-cycling and primary productivity through the retention of nutrients in the sediments.

Abstracts from the 2017–2018 Mineral Deposits Studies Group meeting

Applied Earth Science, 2018

Cobalt in the Congolese Copperbelt mines is commonly recovered from Co-oxi-hydroxides (i.e. heter... more Cobalt in the Congolese Copperbelt mines is commonly recovered from Co-oxi-hydroxides (i.e. heterogenite, asbolane) by acid-leaching under reducing conditions. However, most operations face a limit in the leaching yields of cobalt, which usually do not exceed 80%. The main aim of this work was to investigate the causes of the poor recovery, in order to reconcile the Co recovery with processing techniques. Several concentrate samples from different mine plants of Katanga Copperbelt (Kalukuluku, Mutanda, Mabaya, Kamwali and Fungurume) were selected and subjected to a full mineralogical characterisation by Optical Microscopy (OM), X-Ray Diffraction (XRD), automated mineralogy and Scanning Electron Microscopy by Energy Dispersive Spectroscopy (SEM-EDS) prior and after leaching tests. OM and XRD results were used as background information to build a mineral list for mineral identification during automated mineralogy analyses by Mineralogic Mining System (Zeiss ltd.). Automated mineralogy allowed obtaining mineral maps, modal mineralogy, chemical assays and Co deportment for each specimen prior and after leaching. Mineral maps of the leached samples were useful to observe the occurrences of poorly leached Co-bearing particles which were further investigated by SEM-EDS and X-mapping. The results showed that heterogenite (rarely associated with asbolane) is the main cobalt mineral in Katanga. Mineralogic Mining System was able to discriminate between pure heterogenite, and Si-Al-K-bearing heterogenite, asbolane/heterogenite, Heterogenite+Fe-oxi-hydroxide and Co-bearing mixed phases, which resulted more refractory to leaching. The comparison between modal mineralogy of pre-and post-leached samples indicates a decrease, but not a full leaching of these Co phases: chemical assays and Codeportment, in fact, still reveal the presence of low Co% within Co phases listed above (Table 1). SEM-EDS and Xmapping on single particles of some specimens corroborated the results obtained by Mineralogic.

New evidence from the Wuliji'Oboo fluorite deposit for the role of the paleo‐Pacific Plate and Mongol–Okhotsk suture in creating extensive fluorite mineralization in the Great Xing'an Range, NE China

Geological Journal, 2019

The Wuliji'Oboo fluorite deposit is a newly discovered deposit hosted by volcanic rocks of the Ea... more The Wuliji'Oboo fluorite deposit is a newly discovered deposit hosted by volcanic rocks of the Early Cretaceous Baiyin'gaolao Formation, which are located in the Great Xing'an Range. Fluorite orebodies within this area are controlled by the NNE-trending faults. The ΣREE of fluorite samples ranges from 19.18 to 361.22 ppm, with an average of 131.14 ppm. The homogenization temperatures are concentrated in the ranges of 100-150°C and 230-350°C, while the salinity is concentrated in 0.3-1.0 and 2.0-4.5 wt.% NaCl eqv., and the density has ranges of 0.92-0.96 and 0.75-0.8 g/cm 3 , respectively. The δD V-SMOW values of fluid inclusions within the fluorite range between −122.3‰ and −105.6‰ with a mean of −115.36‰. The δ 18 O V-SMOW of fluorite ranges from −12.0 to −8.5‰, average is −9.9‰. Sm-Nd isotopic data on the fluorite ore yield an isochron age of 122 ± 15 Ma and have ɛ Nd (t) values ranging from +3.15 to +4.16 and (87 Sr/ 86 Sr) i values ranging from 0.704907 to 0.705765. In this contribution, field, petrologic, and geochemical data lead us to the following salient findings: (a) The ore consists of fluorite, quartz, and calcite, with host rock alteration that includes silicification, calcitization, and sericitization. The major element data reveal that the host rocks are a series of highK calc-alkaline rhyolite. The REEs suggest that F-rich fluids in this region might have experienced a longdistance migration. The Tb/Ca-Tb/La diagram confirms a hydrothermal origin for the deposit. (b) Petrographic evidence and fluid inclusions in the fluorites indicate that this deposit might have two ore-forming stages. The ore-forming fluids can be attributed to a NaCl-H 2 OF system with moderate-low temperature, low salinity, and low density and have a meteoric water source, with water/rock reaction as the main mechanism for fluorite precipitation. (c) The deposit was formed in an anorogenic within-plate extensional tectonic setting related to the lithospheric thinning occurring after the Mongolian-Okhotsk Ocean closure.

Asteroids Impacts, Crustal Evolution and Related Mineral Systems with Special Reference to Australia

Modern Approaches in Solid Earth Sciences, 2018

The use of general descriptive names, registered names, trademarks, service marks, etc. in this p... more The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.