Provenance evolution of the Paleoproterozoic metasedimentary cover sequences in northern Fennoscandia: Age distribution, geochemistry, and zircon morphology

Köykkä, Juha; Lahtinen, Raimo; Huhma, Hannu

doi:10.1016/j.precamres.2019.105364

Cited by 33 publications

(23 citation statements)

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“…The unconformably overlying Hauki and Maatavaara quartzites in the Norbotten region are stratigraphically equivalent to the epiclastic-dominated Kumpu Group in Finland (Billström et al, 2010) which has a maximum depositional age of ~1870 Ma (Fig. S2; Köykkä et al, 2019). Calc-alkaline felsic and mafic intrusions of the Haparanda suite were emplaced from ~1886 Ma to ~1872 Ma with a possible later phase at ~1856-1846 Ma (Fig.…”

Section: Guelb Moghrein Cu-au Deposit Mauritania -Neoarchean/paleoproterozoicmentioning

confidence: 92%

Iron oxide copper-gold (IOCG) deposits – A review (part 1): Settings, mineralogy, ore geochemistry and classification

Skirrow¹

2022

Preprint

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Characteristics of ten of the world's metallogenic provinces hosting iron oxide Cu-Au (IOCG) deposits have been critically assessed, including geochronology, geological and tectonothermal evolution, alteration-mineralisation parageneses, and ore geochemistry. A new classification framework is proposed in which IOCG deposits form the major part of a global family of Cu-Au-Fe (± Co, REE) or CGI deposits that also includes Fe-rich Cu-Au deposits lacking significant iron oxides. The CGI family is subdivided on the basis of combined tectonic setting, ore geochemistry, and oxidation state of ore-related mineralogy. Three subtypes of CGI deposits have elevated REE ± U, F and Ba and/or enrichments in Co (± Ni, Bi, Se, Te), with known deposits occurring in Precambrian syn-and post-orogenic settings. A fourth subtype of CGI deposits generally lacks significant enrichments in REE, U, F, Ba, Co, Ni, Bi, Se and Te and occur mainly in Phanerozoic Andean type magmatic arc settings. The REE-and/or Co-rich CGI deposit subtypes are geologically and geochemically distinct from porphyry Cu (-Au), skarn Fe-Cu and iron oxideapatite (IOA) deposits, although there are some shared features. The low-REE-U-Co arc-hosted

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Section: Guelb Moghrein Cu-au Deposit Mauritania -Neoarchean/paleoproterozoicmentioning

confidence: 92%

Iron oxide copper-gold (IOCG) deposits – A review (part 1): Settings, mineralogy, ore geochemistry and classification

Skirrow¹

2022

Preprint

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“…b Stratigraphic column of KB showing stratigraphic setting of Au-Co mineralization. Modified after Huhma et al (2018) with additions from Köykkä et al (2019) and Lahtinen and Köykkä (2020). Section of Au-Co mineralization in the stratigraphy is taken from Vanhanen (2001).…”

Section: Regional Settingmentioning

confidence: 99%

“…Rock descriptions in this geological map are based solely on alteration mineralogy as described by Vanhanen (2001). Modified after Pankka (1992) and Vanhanen (2001) stratigraphy of the KB was further refined (Köykkä et al 2019;Lahtinen and Köykkä 2020) and now includes a formation belonging to the Kumpu Group as the uppermost unit (Fig. 1b).…”

Section: Regional Settingmentioning

confidence: 99%

“…T h e s t r a t i g r a p h i c a l l y l o w e s t u n i t i n t h e Paleoproterozoic basin fill, which overlies the Archean basement, is the continental clastic and shallow marine Posio suite that comprises quartzite and paragneiss (Köykkä et al 2019). Overlying the Posio suite is the Sirniö Formation of the Salla Group.…”

Section: Regional Settingmentioning

confidence: 99%

“…2.3 Ga; e.g., Bekker et al 2004). Finally, sparsely outcropping conglomeratesandstone associations of the Kumpu Group form the uppermost unit in the KB (Köykkä et al 2019).…”

Section: Regional Settingmentioning

confidence: 99%

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Geochemical signatures of mineralizing events in the Juomasuo Au–Co deposit, Kuusamo belt, northeastern Finland

et al. 2021

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The Juomasuo Au–Co deposit, currently classified as an orogenic gold deposit with atypical metal association, is located in the Paleoproterozoic Kuusamo belt in northeastern Finland. The volcano-sedimentary sequence that hosts the deposit was intensely altered, deformed, and metamorphosed to greenschist facies during the 1.93–1.76 Ga Svecofennian orogeny. In this study, we investigate the temporal relationship between Co and Au deposition and the relationship of metal enrichment with protolith composition and alteration mineralogy by utilizing lithogeochemical data and petrographic observations. We also investigate the nature of fluids involved in deposit formation based on sulfide trace element and sulfur isotope LA-ICP-MS data together with tourmaline mineral chemistry and boron isotopes. Classification of original protoliths was made on the basis of geochemically immobile elements; recognized lithologies are metasedimentary rocks, mafic, intermediate-composition, and felsic metavolcanic rocks, and an ultramafic sill. The composition of the host rocks does not control the type or intensity of mineralization. Sulfur isotope values (δ34S − 2.6 to + 7.1‰) and trace element data obtained for pyrite, chalcopyrite, and pyrrhotite indicate that the two geochemically distinct Au–Co and Co ore types formed from fluids of different compositions and origins. A reduced, metamorphic fluid was responsible for deposition of the pyrrhotite-dominant, Co-rich ore, whereas a relatively oxidized fluid deposited the pyrite-dominant Au–Co ore. The main alteration and mineralization stages at Juomasuo are as follows: (1) widespread albitization that predates both types of mineralization; (2) stage 1, Co-rich mineralization associated with chlorite (± biotite ± amphibole) alteration; (3) stage 2, Au–Co mineralization related to sericitization. Crystal-chemical compositions for tourmaline suggest the involvement of evaporite-related fluids in formation of the deposit; boron isotope data also allow for this conclusion. Results of our research indicate that the metal association in the Juomasuo Au–Co deposit was formed by spatially coincident and multiple hydrothermal processes.

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The Mustajärvi orogenic gold occurrence, Central Lapland Greenstone Belt, Finland: a telluride-dominant mineral system

et al. 2020

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The Mustajärvi gold occurrence lies in the southern part of the Paleoproterozoic Central Lapland Greenstone Belt, in proximity to the first-order transcrustal Venejoki thrust fault system. The gold occurrence is structurally controlled by the second-order Mustajärvi shear zone, which is located at the contact between siliciclastic metasedimentary and mafic to ultramafic metavolcanic rocks. The main mineralization comprises a set of parallel veins and sulfidized rocks that are slightly oblique to the shear zone and are hosted by third-order structures likely representing Riedel R-type shears. The gold-mineralized rock at Mustajärvi is associated with pyrite that is present in 0.15- to 1-m-wide quartz-pyrite-tourmaline veins and in zones of massive pyrite in the host rocks with thicknesses ranging from 1.15 to 2 m. In unweathered rock, hypogene gold is hosted by Au- and Au-Bi-telluride micro-inclusions in pyrite, whereas strong weathering at near surface levels has caused a remobilization of gold, resulting in free gold deposited mainly in the cracks of oxidized pyrite. The geochemistry of both mineralization styles is typical of orogenic gold systems with strong enrichments comprising Au, B, Bi, CO2, Te, and Se; and less consistent anomalous amounts of Ag, As, Sb, and W. Unusual for orogenic gold deposits is the strong enrichment of Ni and Co, which leads to the classification of Mustajärvi as orogenic gold occurrence with atypical metal association.

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Provenance evolution of the Paleoproterozoic metasedimentary cover sequences in northern Fennoscandia: Age distribution, geochemistry, and zircon morphology

Cited by 33 publications

References 58 publications

Iron oxide copper-gold (IOCG) deposits – A review (part 1): Settings, mineralogy, ore geochemistry and classification

Iron oxide copper-gold (IOCG) deposits – A review (part 1): Settings, mineralogy, ore geochemistry and classification

Geochemical signatures of mineralizing events in the Juomasuo Au–Co deposit, Kuusamo belt, northeastern Finland

The Mustajärvi orogenic gold occurrence, Central Lapland Greenstone Belt, Finland: a telluride-dominant mineral system

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