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Tellnes |
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Norway |
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Ti
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Super Porphyry Cu and Au
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The Tellnes ilmenite deposit is located in the Sokndal district of far south-west of Norway, some 120 km south-west of Oslo.
The orebody occurs as an ilmenite bearing 931 ±3 Ma norite lense emplaced within the 200 sq. km Åna-Sira massif anorthosite of the 930 to 920 Ma Rogaland Anorthosite Province. The Rogaland Anorthosite Province is an anorthosite-mangerite-charnockite igneous complex of Late-Proterozoic age, characterized by huge anorthosite bodies. It is is part of the Sveconorwegian orogenic province, correlated with the Grenville province in North America. The Rogaland anorthosites and associated Ti-Fe deposits were emplaced during post-collisional magmatic activity period and outcrops in the southwestern part of the Sveco-norwegian orogenic belt. It was intruded into various ortho- and paragneiss complexes that were metamorphosed to granulite facies. Some 70% of the complex lies below the North Sea. The main geological units recognized on-shore are three anorthosite plutons, the Egersund-Ogna, Håland-Helleren
and Åna-Sira anorthosites, and the Bjerkreim-Sokndal intrusion, a folded layered body which comprises a thick series of anorthosite-(leuco)norite-mangerite cumulates capped by massive acidic rocks (quartz mangerite and charnockite). Other less significant components of the Rogaland Anorthosite Province include: i). two leuconorite outliers along the eastern border of the complex; ii). dykes and small jotunitic plutons that cut across the anorthosite bodies and the cumulate series of the Bjerkreim-Sokndal intrusion; and iii). numerous Ti-Fe deposits, which are mainly found in the Håland-Helleren and Åna-Sira anorthosites.
The Tellnes orebody is intrusive into the Åna-Sira anorthosite, the easternmost of the Rogaland anorthosite plutons, which is mainly composed of coarse-grained anorthosite, but also includes more leuco-noritic parts, as well as anorthosito-leuconoritic complexes. The Åna-Sira anorthosite is dome-shaped, with a minimum thickness from gravity data of about 4 km and age of 932±3 Ma from U-Pb dates from zircons.
The sickle shaped 2700 x 450 m Tellnes orebody is intrusive into the surrounding Åna-Sira anorthosite with sharp contacts, numerous cross-cutting apophyses, intrusive breccias and contains xenoliths of the surrounding anorthosite. The three-dimensional shape of the orebody is that of a SE-plunging elongated trough, whose NE and SW flanks dip, respectively, 45 to 50° SW and from almost vertical to NE. On its two extremities it thins into 5 to 10 m thick dykes which range in composition from monzo-norite to quartz-mangerite. These lateral dykes extend for a further 4 km to the NW and 10 km to the SE.
The orebody has a relatively uniform composition. The dominant petrographic facies is a medium-grained ilmenite-rich norite, mainly made up of plagioclase, hemo-ilmenite and orthopyroxene, with subordinate biotite, magnetite, olivine, apatite and at least 22 other accessory minerals in minor to trace amounts, including complex Fe-
Ni-(Co)-Cu sulphides and clinopyroxene.
The principal non-silicate minerals are: Ilmenite, magnetite, chalcopyrite, millerite and pentlandite, with wolframite, pitchblende, chromite, pyrochlore,
Tellnes accounts for up to 13% of the world's annual supply of TiO2 pigment. The ore has an average composition of 39% ilmenite, 2% magnetite, 35% plagioclase, 15% hypersthene, 3.4% biotite and 3.5% accessories. The orebody covers a surface area of 570 000 sq. m.
Production from 1960 to 1999 amounted to: 10.6 Mt of TiO2.
Reserves in 2000 were approximately: 380 Mt @ 18 % TiO2 for 68.4 Mt of TiO2.
For more detail consult the reference(s) listed below.
The most recent source geological information used to prepare this decription was dated: 2003.
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd. Unauthorised copying, reproduction, storage or dissemination prohibited.
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Selected References:
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Diota H, Bolleb O, Lambertb J-M, Launeauc P and Duchesne J-C, 2003 - The Tellnes ilmenite deposit (Rogaland, South Norway): magnetic and petrofabric evidence for emplacement of a Ti-enriched noritic crystal mush in a fracture zone: in J. of Structural Geology v25 pp 481–501
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Wilmart E, Demaiffe D, Duchesne J C 1989 - Geochemical constraints on the genesis of the Tellnes Ilmenite deposit, southwest Norway: in Econ. Geol. v84 pp 1047-1056
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Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge. It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published. While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo, its employees and servants: i). do not warrant, or make any representation regarding the use, or results of the use of the information contained herein as to its correctness, accuracy, currency, or otherwise; and ii). expressly disclaim all liability or responsibility to any person using the information or conclusions contained herein.
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