Geochemical discrimination between barren and mineralized intrusions in the Svecofennian (1.9 Ga) Kotalahti Nickel Belt, Finland

Makkonen, Hannu V.; Mäkinen, Jari; Kontoniemi, Olavi

doi:10.1016/j.oregeorev.2006.05.011

Cited by 21 publications

(24 citation statements)

References 18 publications

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“…According to clinopyroxene-rich peridotites in the Juva area crystallized from uncontaminated magma (Vammala type, Mäkinen, 1987), while orthopyroxenerich peridotites with intercumulus plagioclase (Kotalahti type, Mäkinen, 1987) reflect increased SiO 2 and Al 2 O 3 in the magma, due to contamination by pelitic country rock. Similar conclusions were drawn by Makkonen et al (2007) in a geochemical study of 11 intrusions in the Kotalahti Nickel Belt.…”

Section: Introductionsupporting

confidence: 84%

“…The highest sulfide concentrations are found near the footwall contact. Estimated mineral resources are 0.12 Mt at 0.6 wt.% Ni, 0.3 wt.% Cu and 6.0 wt.% S (Makkonen et al, 2007).…”

Section: Törmälämentioning

confidence: 99%

“…Tuisku & Makkonen, 1999). Sulfides (pyrrhotite, pentlandite, chalcopyrite) occur only sporadically and metallic copper is found in some samples (Makkonen et al, 2007).…”

Section: Majasaarimentioning

confidence: 99%

“…These features suggest that olivine has been transported and that intrusion took place in several phases. Sulfides are very rare in the Luusniemi intrusion and they have been oxidised to magnetite in the NW part of the intrusion (Makkonen et al, 2007).…”

Section: Luusniemimentioning

confidence: 99%

“…Metapyroxenite or hornblendite is found locally along intrusion margins. Sulfide disseminations (pyrrhotite, chalcopyrite, rare pentlandite) are common in peridotite, but are relatively poor in nickel and copper (Makkonen et al, 2007).…”

Section: Kylmälahtimentioning

confidence: 99%

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Sm-Nd data for mafic-ultramafic intrusions in the Svecofennian (1.88 Ga) Kotalahti Nickel Belt, Finland - Implications for crustal contamination at the Archaean/Proterozoic boundary

Makkonen¹,

Huhma²

2007

Bull Geol Soc Finland

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Sm-Nd data were determined for eight mafic-ultramafic intrusions from the Svecofennian (1.88 Ga) Kotalahti Nickel Belt, Finland. The intrusions represent both mineralized and barren types and are located at varying distances from the Archaean/Proterozoic boundary. The samples for the 23 Sm-Nd isotope analyses were taken mostly from the ultramafic differentiates. Results show a range in initial ε Nd values at 1880 Ma from -2.4 to +2.0. No relaNo relationship can be found between the degree of Ni mineralization and initial ε Nd values, while a correlation with the geological domain and country rocks is evident. The Majasaari and Törmälä intrusions, which have positive ε Nd values, were emplaced within the Svecofennian domain in proximity to 1.92 Ga tonalitic gneisses, which have previously yielded initial ε Nd values of ca. +3. In contrast, the Luusniemi intrusion, which has an ε Nd value of -2.4 is situated close to exposed Archaean crust. Excluding two analyses from the Rytky intruArchaean crust. Excluding two analyses from the Rytky intru-. Excluding two analyses from the Rytky intrusion, all data from the Koirus N, Koirus S, Kotalahti, Rytky and Kylmälahti intrusions, within error limits, fall in the range -0.7 ± 0.3. The results support the concept of contamination by Archaean material in proximity to the currently exposed craton margin. The composition of the proposed parental magma for the intrusions is close to EMORB, with initial ε Nd values near +4.

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Section: Introductionsupporting

confidence: 84%

“…The highest sulfide concentrations are found near the footwall contact. Estimated mineral resources are 0.12 Mt at 0.6 wt.% Ni, 0.3 wt.% Cu and 6.0 wt.% S (Makkonen et al, 2007).…”

Section: Törmälämentioning

confidence: 99%

“…Tuisku & Makkonen, 1999). Sulfides (pyrrhotite, pentlandite, chalcopyrite) occur only sporadically and metallic copper is found in some samples (Makkonen et al, 2007).…”

Section: Majasaarimentioning

confidence: 99%

Section: Luusniemimentioning

confidence: 99%

Section: Kylmälahtimentioning

confidence: 99%

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Sm-Nd data for mafic-ultramafic intrusions in the Svecofennian (1.88 Ga) Kotalahti Nickel Belt, Finland - Implications for crustal contamination at the Archaean/Proterozoic boundary

Makkonen¹,

Huhma²

2007

Bull Geol Soc Finland

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Genesis of the Neoarchean subduction‐related Taoke Ni–Cu‐(PGE) sulphide deposit in the North China Craton: Constraints from Os–S isotopes and PGE geochemistry

et al. 2021

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Archean magmatic Ni‐Cu‐[platinum‐group element (PGE)] deposits are very important and mainly associated with komatiitic rocks in intracratonic rift zones throughout the world. However, the Taoke Ni‐Cu‐(PGE) deposit in the North China Craton, which is the oldest (Neoarchean, 2,537 Ma) magmatic sulphide deposit in China, and is genetically related to the subduction zone. The intrusion is predominantly composed of a small ultramafic body (olivine websterite) and a much larger gabbroic body (gabbronorite). Sulphide mineralization is mainly associated with the ultramafic body with average grades of 0.66 wt% Ni, 0.62 wt% Cu and ~1 g/t PGE. Sulphides of the Taoke deposit are characterized by a chalcopyrite + pentlandite + pyrrhotite + millerite assemblage, which hosts variable amounts of platinum‐group minerals. Good correlations are found for Pd versus individual Ir subgroup of platinum‐group elements (IPGEs; i.e., Pd vs. Os, Ir, Ru, and Rh) and for Ir and Pd subgroup of platinum‐group elements (PPGEs; i.e., Ir vs. Pt and Pd), indicating that the PGE contents of immiscible sulphide liquids in the Taoke deposit are mainly controlled by the initial PGE concentrations in the parental magma and R factor (magma/sulphide mass ratio). Based on our calculations, the initial contents of Ir and Pd in the parental magma are estimated to be 0.13 and 5.6 ppb, respectively, suggesting that the parental magma of the Taoke deposit is PGE undepleted. The multiple sulphur isotopes can provide direct indications of the source of sulphur for the Archean intrusion. The γOs(t) values and Archean crustal sulphur (three samples have anomalous Δ33S values <−0.1‰) suggest that the addition of crustal sulphur occurred in the magma. Fractional crystallization and the addition of crustal sulphur are the most likely key factors for sulphide saturation in the Taoke mafic magma.

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Introduction

Piña¹

2018

SpringerBriefs in World Mineral Deposits

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Geochemical discrimination between barren and mineralized intrusions in the Svecofennian (1.9 Ga) Kotalahti Nickel Belt, Finland

Cited by 21 publications

References 18 publications

Sm-Nd data for mafic-ultramafic intrusions in the Svecofennian (1.88 Ga) Kotalahti Nickel Belt, Finland - Implications for crustal contamination at the Archaean/Proterozoic boundary

Sm-Nd data for mafic-ultramafic intrusions in the Svecofennian (1.88 Ga) Kotalahti Nickel Belt, Finland - Implications for crustal contamination at the Archaean/Proterozoic boundary

Genesis of the Neoarchean subduction‐related Taoke Ni–Cu‐(PGE) sulphide deposit in the North China Craton: Constraints from Os–S isotopes and PGE geochemistry

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