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Petrology and lithogeochemistry of the host rocks to the Nautanen Cu-Au deposit, Gällivare area, northern Sweden

McGimpsey, Ian (2010) In Dissertations in Geology at Lund University
Department of Geology
Abstract
The Nautanen Cu-Au deposit is located 75 km north of the Arctic circle, and 10 km northeast of the town of Gällivare in northern Sweden. Nautanen is just 8 km west of the giant Malmberget apatite-iron ore deposit and 15 km north of one of Europe’s largest copper producers, the Aitik Cu (Au) porphyry deposit. Nautanen is described as an Iron Oxide Copper Gold (IOCG) deposit or hybrid IOCG and contains a core of high grade resources of 0.63 Mt with 2.36% Cu, 1.3 ppm Au, 11 ppm Ag, or using a lower cut-off some 3 Mt with 0.75% Cu, 0.52 ppm Au, and 2 ppm Ag.
Nautanen is hosted in strongly altered and tectonically deformed Svecofennian volcanoclastic rocks on a major shear zone, the Nautanen Deformation Zone (NDZ). Alteration is dominated by... (More)
The Nautanen Cu-Au deposit is located 75 km north of the Arctic circle, and 10 km northeast of the town of Gällivare in northern Sweden. Nautanen is just 8 km west of the giant Malmberget apatite-iron ore deposit and 15 km north of one of Europe’s largest copper producers, the Aitik Cu (Au) porphyry deposit. Nautanen is described as an Iron Oxide Copper Gold (IOCG) deposit or hybrid IOCG and contains a core of high grade resources of 0.63 Mt with 2.36% Cu, 1.3 ppm Au, 11 ppm Ag, or using a lower cut-off some 3 Mt with 0.75% Cu, 0.52 ppm Au, and 2 ppm Ag.
Nautanen is hosted in strongly altered and tectonically deformed Svecofennian volcanoclastic rocks on a major shear zone, the Nautanen Deformation Zone (NDZ). Alteration is dominated by scapolite, K-feldspar, epidote, sericite, and amphibole. Nautanen host rocks consist of steeply dipping, repeating layers of shoshonitic andesites, that were formed in a continental arc setting. The Nautanen rocks have lithogeochemical values characteristic of the low titanium, low zirconium Porphyrite Group of metavolcanics found in Norrbotten and are lithogeochemically similar to the volcanic host rocks to the Aitik deposit.

The high amount of magnetite and locally apatite at Nautanen, suggests a possible connection to the Malmberget apatite-iron ore. Titanite and allanite ages of c. 1.78 Ga at Nautanen correspond to the timing of IOCG overprinting noted at Aitik. Similar high salinity fluid inclusions as those noted as porphyry-related in the Aitik deposit have also been observed in Nautanen, indicating that porphyry type mineralization may have been present at the Nautanen locality as well. Multiple episodes of circulation of fluids and remobilization of ore minerals along the NDZ between Nautanen and Aitik have probably occurred.

Variations in tectonic processes, alteration, and magma fractionation have likely led to the small differences seen between the lithogeochemically indicated origins of the host rocks to the Nautanen and Aitik deposits. (Less)
Abstract (Swedish)
Koppar-guld fyndigheten Nautanen är belägen 75 km norr om polcirkeln, och 10 km nordost om Gällivare i norra Sverige. Fyndigheten ligger endast 8 km från den stora apatit-järnmalmen i Malmberget och 15 km norr om en av Europas största kopparproducenter, porfyrkoppar-(guld)malmen Aitik. Nautanen beskrivs som en järnoxid-koppar-guld (IOCG) fyndighet eller en hybrid IOCG med en kärna av höghaltiga reserver på 0.63 Mt med 2.36% Cu, 1.3 ppm Au, 11 ppm Ag, och med en lägre cut-off 3 Mt med 0.75% Cu, 0.52 ppm Au och 2 ppm Ag.

Nautanen sitter i kraftigt omvandlade och tektoniskt deformerade Svekofenniska vulkanoklastiska bergarter belägna på en större skjuvzon, Nautanen Deformation Zone (NDZ). Omvandlingen domineras av skapolit, kalifältspat,... (More)
Koppar-guld fyndigheten Nautanen är belägen 75 km norr om polcirkeln, och 10 km nordost om Gällivare i norra Sverige. Fyndigheten ligger endast 8 km från den stora apatit-järnmalmen i Malmberget och 15 km norr om en av Europas största kopparproducenter, porfyrkoppar-(guld)malmen Aitik. Nautanen beskrivs som en järnoxid-koppar-guld (IOCG) fyndighet eller en hybrid IOCG med en kärna av höghaltiga reserver på 0.63 Mt med 2.36% Cu, 1.3 ppm Au, 11 ppm Ag, och med en lägre cut-off 3 Mt med 0.75% Cu, 0.52 ppm Au och 2 ppm Ag.

Nautanen sitter i kraftigt omvandlade och tektoniskt deformerade Svekofenniska vulkanoklastiska bergarter belägna på en större skjuvzon, Nautanen Deformation Zone (NDZ). Omvandlingen domineras av skapolit, kalifältspat, epidot, sericit och amfibol. Värdbergarterna utgörs av upprepade lager av brant stupande shoshonitiska andesiter, bildade i en kontinental öbåge-miljö. Bergarterna i Nautanen har en litogeokemisk signatur liknande den i de låg-Ti, låg-Zr metavulkaniska bergarter tillhörande porfyritgruppen i Norrbotten, och sammanfaller litogeokemiskt med Aitikmalmens vulkaniska värdbergarter.

Den stora mängden magnetit och ställvis apatit i Nautanen, antyder om ett möjligt samband mellan Nautanen-fyndigheten och Malmbergets apatit-järnmalm. Titanit- och allanit-åldrar på ca 1.78 Ga i Nautanen överensstämmer med tidpunkten för IOCG-överprägling observerad i Aitik. Liknande hög-salina vätskeinneslutningar som de som tolkats som porfyrkoppar-relaterade i Aitikmalmen, har också observerats i Nautanen, vilket tyder på att en mineraliseringshändelse av porfyrkoppar-typ även kan ha skett i Nautanen. Multipla episoder av cirkulerande fluider och remobilisering av malmmineral längst NDZ mellan Nautanen och Aitik har troligtvis ägt rum.
Variationer i tektoniska processer, omvandling och magmafraktionering har sannolikt lett till de små skillnader som observerats mellan det litogeokemiskt indikerade ursprunget hos värdbergarterna till Nautanenmineraliseringen och Aitikmalmen. (Less)
Please use this url to cite or link to this publication:
author
McGimpsey, Ian
supervisor
organization
alternative title
Petrologi och bergartsgeokemi för värdbergarterna till Nautanens Cu-Au mineralisering, Gällivareområdet, norra Sverige
year
type
H2 - Master's Degree (Two Years)
subject
keywords
geography, geology, petrology, lithogeochemistry, Nautanen Cu-Au deposit, Gällivare, northern Sweden
publication/series
Dissertations in Geology at Lund University
report number
270
funder
Boliden Mineral AB
language
English
additional info
Christina Wanhainen, Luleå University of Technology och Roger Nordin, Boliden AB.
id
2278587
date added to LUP
2012-01-10 13:09:13
date last changed
2012-01-10 13:09:13
@misc{2278587,
  abstract     = {The Nautanen Cu-Au deposit is located 75 km north of the Arctic circle, and 10 km northeast of the town of Gällivare in northern Sweden. Nautanen is just 8 km west of the giant Malmberget apatite-iron ore deposit and 15 km north of one of Europe’s largest copper producers, the Aitik Cu (Au) porphyry deposit. Nautanen is described as an Iron Oxide Copper Gold (IOCG) deposit or hybrid IOCG and contains a core of high grade resources of 0.63 Mt with 2.36% Cu, 1.3 ppm Au, 11 ppm Ag, or using a lower cut-off some 3 Mt with 0.75% Cu, 0.52 ppm Au, and 2 ppm Ag.
Nautanen is hosted in strongly altered and tectonically deformed Svecofennian volcanoclastic rocks on a major shear zone, the Nautanen Deformation Zone (NDZ). Alteration is dominated by scapolite, K-feldspar, epidote, sericite, and amphibole. Nautanen host rocks consist of steeply dipping, repeating layers of shoshonitic andesites, that were formed in a continental arc setting. The Nautanen rocks have lithogeochemical values characteristic of the low titanium, low zirconium Porphyrite Group of metavolcanics found in Norrbotten and are lithogeochemically similar to the volcanic host rocks to the Aitik deposit. 

The high amount of magnetite and locally apatite at Nautanen, suggests a possible connection to the Malmberget apatite-iron ore. Titanite and allanite ages of c. 1.78 Ga at Nautanen correspond to the timing of IOCG overprinting noted at Aitik. Similar high salinity fluid inclusions as those noted as porphyry-related in the Aitik deposit have also been observed in Nautanen, indicating that porphyry type mineralization may have been present at the Nautanen locality as well. Multiple episodes of circulation of fluids and remobilization of ore minerals along the NDZ between Nautanen and Aitik have probably occurred. 

Variations in tectonic processes, alteration, and magma fractionation have likely led to the small differences seen between the lithogeochemically indicated origins of the host rocks to the Nautanen and Aitik deposits.},
  author       = {McGimpsey, Ian},
  keyword      = {geography,geology,petrology,lithogeochemistry,Nautanen Cu-Au deposit,Gällivare,northern Sweden},
  language     = {eng},
  note         = {Student Paper},
  series       = {Dissertations in Geology at Lund University},
  title        = {Petrology and lithogeochemistry of the host rocks to the Nautanen Cu-Au deposit, Gällivare area, northern Sweden},
  year         = {2010},
}