Norsk versjon
	THE ORE DATABASE
	Deposit 1111 - 008 Storgangen
	(Object Id: 4903) (Last updated: 13.03.2024)

Products

	Element/product	Crude ore grade or quality	Reg. date
	Ti	11 %	13.03.2024
	TiO2	18 %	05.10.2001

Operations

	From - To	Activity	Comments
	1902 - 1964	Regular production	Company/Institution :Titania A/S
			Storgangen was mined by Titania A/S from 1902 to 1964. The mine produced a total of more than 10 Mt. of ore containing 18-19% TiO2, accounting for 11-13% of the world production of TiO2 during that periode (Krause m. fl. 1985).

Mineralization

	Era:	Proterozoic	Period:	Neoproterozoic
	Genesis:	Orthomagmatic formation	Form:
	Main texture:	Banded	Min. distribution:	Semi-massive (20-50 % ore minerals)

Main grain size:

Medium grained (1-3 mm)

Main alteration:

	Strike/Dip:		Direction:
			Plunge:

Ti-deposit type(s)

	Main type:	Magmatic	Ilm/Mt-ratio:
	Sub type:	Mt +/- Ilm +/- Ap in mafic intrusion	%TiO(Ore):
	Titanium province:	Rogaland anorthosite province	%P2O5(Ore):
	Host rock:	Norite	%MgO(Ilm):
	Main Ti mineral:	Ilmenite	%V2O3(Mt):
			ppm U (Rutile):

Stratigraphic classification of host rock

Era:

Proterozoic

Period:

Neoproterozoic

	Province:	South Norwegian Basement Province
	Geotec.unit:
	Tectonic complex:
	Igneous complex:	Egersund Anorthosite Complex

Group:

Formation:

Mineralogy

	Relationship	Mineral	Amount
	Gangue mineral	Pyroxene	Major mineral (>10%)
	Gangue mineral	Plagioclase	Major mineral (>10%)
	Gangue mineral	Biotite	Subordinate mineral (1-10%)
	Ore mineral	Ilmenite	Major mineral (>10%)
	Ore mineral	Titanomagnetite	Major mineral (>10%)
	Ore mineral	Pyrrhotite	Subordinate mineral (1-10%)
	Ore mineral	Pyrite	Subordinate mineral (1-10%)
	Ore mineral	Chalcopyrite	Accessory mineral (<1%)
	Ore mineral	Pentlandite	Accessory mineral (<1%)

Lithology:

	Relationship	Rock	Origin
	Host rock	Norite	Intrusive Original rock :Norite
	Wall rock	Anorthosite	Intrusive Original rock :Anorthosite

Information(s) in free text format

Free text

The following description is based on Duchesne and Schiellerup (in Duchesne 2001). The Storgangen orebody forms a dyke in the Åna Sira anorthosite (4 km long, up to 50 m thick) with numerous offshoots. The anorthosite, which constitutes the hanging wall of the dyke, is always foliated concordantly with the contact. Strong foliation in the westernmost part of the intrusion, close to the anorthosite margin, is also evident, and accompanied by deformation and granulation of plagioclase grains. The observations imply that the Storgangen dyke had intruded and solidified prior to the final deformation of the anorthosite (Paludan et al. 1994; Bolle et al. 2000). The orebody is concordantly layered on a cm to m scale, locally with some irregularities. The layering is generally dipping in a northerly direction at an angle of 40-60°, and is conspicuously isomodal throughout the sequence. In the westernmost outcrops, modal layering strikes parallel to the layering in the adjacent parts of the BKSK. The BKSK cumulates crystallized from a much larger magma chamber, where modal layering developed sub-horizontally. The concordant and parallel behaviour of the BKSK and Storgangen layering seem to indicate that the latter originated as a sill-like body. The mineralogy comprises plagioclase, Ca-poor and Ca-rich pyroxene, apatite, Fe-Ti oxides, green chromian spinel and a variety of minor sulfides, as well as baddeleyite. Cumulus Ca-rich pyroxene is rare and only seems to be present in the uppermost part of the layered sequence. Late entry of Ca-rich pyroxene is in accordance with up-section being equivalent to stratigraphic up, and the hanging wall thus represents the roof of the Storgangen magma chamber. Apatite is highly accessory but does not seem to be stratigraphically confined. The complete section is generally rich in oxides, but the most extensive oxide-rich zones occur in the lower half of the stratigraphy. At the footwall, the norite contains a hemo-ilmenite (Hem13) associated with magnetite and pleonastc spinel. The mafic mineral content decreases somewhat upwards, and there is a systematic decrease in An content of plagioclase (An55 to An43) and En content of Ca-poor pyroxene (En75 to En66), though distinct lateral variation exists (Krause et al. 1985, and current contribution). The MgO content of ilmenite is strongly correlated with the En content of coexisting Ca-poor pyroxene, and ilmenite in Storgangen evolves from 3-3.5% MgO to around 2% MgO.

Bibliography:

From NGU's Reference Archive:

Paludan, Johanne , 1995

	Structural evolution of the Bjerkreim-Sokndal layered intrusion, SW Norway: micro to macro scale studies.

;AVHANDLING

Paludan, Johanne; Hansen, Ulla B.; Olesen, Niels Ø. , 1994

	Structural evolution of the Precambrian Bjerkreim-Sokndal intrusion, south Norway

;Norsk geologisk forening;TIDSSKRIFTARTIKKEL;Norsk geologisk tidsskrift; No.74 (4);185-198 pages

Abstract:

The structures of the northwestern part of the Precambrian Bjerkreim-Sokndal intrusion are studied from micro- to macro-scale. Meso-scale structures are dominated by (1) modal layering of igneous origin (Sg) and (2) prominent linear and planar fabrics (L1/S1), defined by the shape-preferred orientation of mineral aggregates. In most places So and S, are parallel, and together they define an isoclinal syncline with a southeastwards plunging fold axis. The linear fabric (L1) is subparallel to the fold axis in the hinge zone and converges towards this zone in the limbs. The intensity and type of fabric vary across the fold. In the hinge zone the L-fabric is dominant, whereas the rocks in the limbs display a combined S- and L-fabric. The intensity of the fabric is closely tied with microstructural indications of plastic deformation, such as lattice bending and kinking, polygonization and recrystallization. All of this points to one major phase of solid state deformation. Estimates of the strain state are based on regional variations in the shape of olivine grains and aggregates from two igneous units.Extensions of up to 100% are observed in the hinge zone, and flattening around 40% is observed in the south- ern limb. Rheological considerations suggest that these are minimum values. In our interpretation, the deformation was the result of passive subsidence of the intrusive rocks, induced by gravitational instabilities in the area (inverse diapirism) A convergent flow pattern led to the formation of L-tec- tonites in the hinge zone and an additional shear component along the limb led to the formation of L/S-tectonites. A series of monzonorite dykes (the Lomland dykes) and a number of minor shear zones all post-date the major deformation. The dykes and shear zones may be coeval.

References not to be found in NGU's Reference Archive.:

Bolle, O., Diot, H. & Duchesne, J.C. 2000: Magnetic fabric and deformation in charnockitic igneous rocks of the Bjerkreim-Sokndal layered intrusion (Rogaland, Southwest Norway). J. Struct. Geol. 22, 647-667.

Duchesne, J.-C. 2001: The Rogaland Intrusive Massifs - an excursion guide. NGU Report 2001.029, 139 p. (ISBN 82-7385-198-2).

Name of Locality: Aursland skjerp

(Object Id: 13672 8,01,00)

Location

County:

Rogaland

Municipality:

Sokndal (1111)

Map 1:50000:

Sokndal (1311-4)

Map 1:250000:

Mandal

Coordinate system:

EU89-UTM Zone 32

East:

346400 m.

North:

6471899 m.

Longitude:

6.3745360

Latitude:

58.3610040

Show on map

Resource

	Resource Type:	Ferrous metals(Fe, Mn, Ti)	Resource Subtype:	Iron-Titanium
			Element(s):	Fe Ti P

Information(s) in free text format

Free text

Aursland skjerp represent the easternmost extension of the Storgangen inrusion. Two 1-3 m thick lentoid or sheet-like bodies of mafic ilmenite-norite and orthopyroxenite are found elongated roughly NW-SE. The length is about 35 m for the southern lens and 100 m for the northern lens. Most likely connected with the Storgangen intrusion. Not to be confused with Aursland 1, which is part of the Blåfjell deposit field.

Name of Locality: Sidegangen

(Object Id: 13673 8,02,00)

Location

County:

Rogaland

Municipality:

Sokndal (1111)

Map 1:50000:

Sokndal (1311-4)

Map 1:250000:

Mandal

Coordinate system:

EU89-UTM Zone 32

East:

344299 m.

North:

6472199 m.

Longitude:

6.3384820

Latitude:

58.3629550

Show on map

Resource

	Resource Type:	Ferrous metals(Fe, Mn, Ti)	Resource Subtype:	Iron-Titanium
			Element(s):	Fe Ti P

Information(s) in free text format

Free text

The westernmost apophysis to the Storgangen intrusion extending into the hangingwall contact of the intrusion for about 350 m.

Name of Locality: Sidegangen 2

(Object Id: 13674 8,03,00)

Location

County:

Rogaland

Municipality:

Sokndal (1111)

Map 1:50000:

Sokndal (1311-4)

Map 1:250000:

Mandal

Coordinate system:

EU89-UTM Zone 32

East:

344699 m.

North:

6472350 m.

Longitude:

6.3452100

Latitude:

58.3644430

Show on map

Resource

	Resource Type:	Ferrous metals(Fe, Mn, Ti)	Resource Subtype:	Iron-Titanium
			Element(s):	Fe Ti P

Information(s) in free text format

Free text

Sidegangen 2 is an apophysis to the Storgangen intrusion extending into the hangingwall contact of the intrusion for a few 100 m. Sidegangen 2 is possibly connected to "Sidegangen 2 fortsettelse", which forms a similar lineament further to the north.

Name of Locality: Sidegangen 2 forts.

(Object Id: 13675 8,04,00)

Location

County:

Rogaland

Municipality:

Sokndal (1111)

Map 1:50000:

Sokndal (1311-4)

Map 1:250000:

Mandal

Coordinate system:

EU89-UTM Zone 32

East:

344849 m.

North:

6473000 m.

Longitude:

6.3473330

Latitude:

58.3703280

Show on map

Resource

	Resource Type:	Ferrous metals(Fe, Mn, Ti)	Resource Subtype:	Iron-Titanium
			Element(s):	Fe Ti P

Information(s) in free text format

Free text

Sidegangen 2 fortsettelse represent the possible extension of an apophysis to the Storgangen intrusion called "Sidegangen 2". Both the apophysis and Sidegangen 2 fortsettelse are dykes consisting of ilmenite-rich norite.

Name of Locality: Sidegangen 3

(Object Id: 13676 8,05,00)

Location

County:

Rogaland

Municipality:

Sokndal (1111)

Map 1:50000:

Sokndal (1311-4)

Map 1:250000:

Mandal

Coordinate system:

EU89-UTM Zone 32

East:

345199 m.

North:

6472299 m.

Longitude:

6.3537800

Latitude:

58.3641710

Show on map

Resource

	Resource Type:	Ferrous metals(Fe, Mn, Ti)	Resource Subtype:	Iron-Titanium
			Element(s):	Fe Ti P

Information(s) in free text format

Free text

Sidegangen 3 is the easternmost apophysis to the Storgangen intrusion extending into the hangingwall contact of the intrusion for a few 100 m. The dyke consists of ilmenite-rich norite.

---

The fact sheet was created on 02.05.2024

Questions or comments regarding the fact sheet can be emailed to: ressursdatabaser@ngu.no

Copyright © 2024 Geological Survey of Norway