Stratigraphy, petrology, and platinum-group element mineralization of the early Proterozoic Penikat layered intrusion, northern Finland

Alapieti, T. T.; Lahtinen, J. J.

doi:10.2113/gsecongeo.81.5.1126

Cited by 55 publications

(25 citation statements)

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“…The 2440 Ma old (Alapieti and Lahtinen 1986) Penikat intrusion belongs to a group of intrusions forming the 300 km long Tornio-Näränkävaara Belt that extends from east Sweden to south-west Finland. The Penikat intrusion is located ~ 70 km south of the Arctic Circle on the northern side of the Gulf of Bothnia ( Fig.…”

Section: Penikat Intrusionmentioning

confidence: 99%

“…The mafic Loljunmaa Dyke located east of the Kilka block is co-magmatic to the intrusion and may represent a part of its feeder channel. The intrusion has been divided into three main Wilson (1996) and Wilson and Prendergast (1989) units: the Marginal series, the Layered series and the granophyres (Alapieti and Lahtinen 1986). The Layered series consists of cyclic units of ultramafic, gabbroic, and anorthositic rocks which have further been divided, based on the variation in occurrence of cumulus minerals, into five megacyclic units referred to as Megacyclic Unit I to V (Fig.…”

Section: Penikat Intrusionmentioning

confidence: 99%

“…The basal units (Megacyclic units I to III) consist mainly of ultramafic rocks with minor mafic rocks where the upper units (Megacyclic units IV and V) are mainly formed by mafic rocks with minor ultramafic rocks (Alapieti and Lahtinen 2002). The PGE-rich mineralization is found in three distinct layers (SJ, AP and PV reefs) within the Megacyclic unit IV consisting, from bottom to top, of a 10 to 20 m thick layer of ultramafic cumulates overlain by a thick sequence of gabbroic and anorthositic cumulates (Alapieti and Lahtinen 1986). The Penikat Intrusion underwent complex deformation and metamorphism during the Svecokarelian Orogeny resulting in pervasive alteration of the cumulate rocks (Alapieti and Halkoaho 1995).…”

Section: Penikat Intrusionmentioning

confidence: 99%

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Platinum-Group Element Deposits in Layered Intrusions: Recent Advances in the Understanding of the Ore Forming Processes

Godel

2015

Springer Geology

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Section: Penikat Intrusionmentioning

confidence: 99%

Section: Penikat Intrusionmentioning

confidence: 99%

Section: Penikat Intrusionmentioning

confidence: 99%

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Platinum-Group Element Deposits in Layered Intrusions: Recent Advances in the Understanding of the Ore Forming Processes

Godel

2015

Springer Geology

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“…Bushveld, Laouni and the Early Proterozoic Penikat, Koitelainen, Burakovsky and Last-Yavr (Cameron 1979;Alapieti and Lahtinen 1986;Lorand et al 1987;Tarkian and Mutanen 1987;Barkov et al 1994Barkov et al , 1996. Due to its enrichment in Zr and REE, Tarkian and Mutanen (1987) envisaged loveringite to have crystallised from a crustally contaminated mafic magma in the Koitelainen intrusion in northern Finland.…”

Section: Accessory Minerals In the Lower Zonementioning

confidence: 99%

Microtextural characterisation of the Lower Zone in the western limb of the Bushveld Complex, South Africa: evidence for extensive melt migration within a sill complex

Karykowski

2017

Contrib Mineral Petrol

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by plagioclase, clinopyroxene and other late stage phases, shows variable ratios of these minerals ranging from ca. 21:15:64 to 75:17:8. In comparison to modelled expected ratios, most of the analysed rocks have higher amounts of early crystallising interstitial phases (e.g. plagioclase, clinopyroxene), relative to late crystallising phases (e.g. quartz, alkali feldspar). Therefore, interstitial melt must have migrated at different stages of fractionation during cumulate solidification, as a consequence of either compaction or displacement by convecting interstitial liquids. Two samples, however, show the opposite: late phases are relatively more abundant than early ones, which is consistent with a convection-driven replacement of primitive interstitial liquid by more evolved liquid. These results have important implications for the interpretation of the Lower Zone and, by extension, for layered intrusions in general: (1) interstitial sulphide mineralisation may be introduced into a cumulate through infiltrating melts, i.e. the liquid components of a sulphur-saturated crystal mush are not withheld from further migration, upon interaction with a cumulate pile; (2) most importantly, late stage minerals, such as zircon, rarely crystallise from trapped liquid that was initially in equilibrium with the cumulate. Therefore, dating of interstitial zircon from cumulates is unlikely to record the actual timing of emplacement, but merely the crystallisation of a later episode of residual melt that migrated through the cumulate.

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“…Many other large layered intrusions, including the Great Dyke of Zimbabwe (Wilson et al 1989), the Munni Munni (Barnes et al 1990) and Windimura intrusions (Parks & Hill 1986) of Western Australia, the Skaergaard intrusion of Greenland (Andersen et al 1998), and the Penikat intrusion of northern Finland (Alapieti & Lahtinen 1986) host only minor occurrences of disseminated stratiform sulfide, generally some distance above the base of the intrusions. These are, however, commonly highly enriched in PGE.…”

Section: Other Large Layered Intrusionsmentioning

confidence: 99%

WHY ARE THERE NO MAJOR Ni Cu SULFIDE DEPOSITS IN LARGE LAYERED MAFIC-ULTRAMAFIC INTRUSIONS?

Maier¹,

Waal

2001

The Canadian Mineralogist

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Large, layered intrusions throughout the world are characterized by a remarkable paucity in economically important magmatic Ni-Cu sulfide deposits. The Sudbury intrusion in Canada is a notable exception, but sulfide ores there were formed by a unique combination of processes involving crustal melting in response to a meteorite impact. Economically important magmatic Ni-Cu sulfide deposits tend to occur in magma conduit systems. Such an environment has been documented at Noril'sk, Jinchuan, and the recently discovered Uitkomst deposit of South Africa and the Voisey's Bay intrusion of Labrador, Canada, which are associated with the Bushveld Complex and the Nain Plutonic Suite, respectively. The enhanced ore potential of conduit systems is attributed to their specific flow environment and to the exploitation of the conduits by multiple flows of magma. Sulfides that were entrained and transported by ascending silicate magma were concentrated in the widened parts of the conduits and, at Voisey's Bay, near the exit of the conduit into a larger chamber, owing to a decrease in the flow velocity of the magma. Further, the precipitated sulfides were upgraded by means of reaction with continued surges of undepleted magma using the same conduit. Thus, exploration for magmatic Ni-Cu sulfide ores should be redirected from layered intrusions to their associated conduit systems.

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Stratigraphy, petrology, and platinum-group element mineralization of the early Proterozoic Penikat layered intrusion, northern Finland

Cited by 55 publications

References 0 publications

Platinum-Group Element Deposits in Layered Intrusions: Recent Advances in the Understanding of the Ore Forming Processes

Platinum-Group Element Deposits in Layered Intrusions: Recent Advances in the Understanding of the Ore Forming Processes

Microtextural characterisation of the Lower Zone in the western limb of the Bushveld Complex, South Africa: evidence for extensive melt migration within a sill complex

WHY ARE THERE NO MAJOR Ni Cu SULFIDE DEPOSITS IN LARGE LAYERED MAFIC-ULTRAMAFIC INTRUSIONS?

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