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	INDUSTRIMINERALDATABASEN
	Registrering 1573 - 301 Skjølberg
	(Objekt Id: 7865) (Sist oppdatert: 03.06.2021)

Mineralisering

	Genese:		Form:
	Hovedtekstur:		Min. fordeling:

Kornstørrelse:

	Strøk/Fall:		Retning:
			Feltstupning:

Stratigrafisk klassifikasjon av vertsbergart

Æra:

Paleozoikum

Periode:

	Provins:
	Geotek.enhet:
	Tektonisk complex:
	Intrusivt komplex:

Gruppe:

Formasjon:

Skjølbergformasjonen

Opplysning(er) i fritekstformat

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Skjølbergkalken oppter som en del av den mellom-ordoviciske sekvens med vulkanitter og kalksteiner på sydlige Smøla. Kalken har en sammensetning som er egnet til sement, men relieffet på flate Smøla gjør at ressursene som kan være egnet til uttak er begrenset. Ved Skjølberg, langs Vestsideveien/fylkesveg 6200 (tidligere en del av fv 669), finnes en rekke vegskjæringer med kalk. Kalken opptrer komplekst sammenfingret med intermediære og basiske vulkanitter med skarndannelse og fossiler. Det er mer kalk i vegskjæringene enn det som fremgår på berggrunnskartet (Fediuk F. 1975. Smøla, berggrunnsgeologisk kart 1321 - 1 M. 1:50 000 Norges geologiske undersøkelse). En liten prøvedrift har vært utført like ved gården Skjølberg. Punktet lå frem til mai 2021 midt i myra ca 2 km nord for Skjølberg (EU89 UTM sone 32 449301 7026493) med dioritt i de nærmeste fastfjellsblotningene, men ble da flyttet til EU89 UTM sone 32 449979 7024627. I følge Fediuk et al (1977) fremstår kalksteinen som relativt ren i håndstykker, men på grunn av bergartens heterogenitet er den ikke økonomisk interessant.

Litteraturfortegnelser:

Fra NGU's Referansearkiv.:

Bruton, David L.; Bockelie, J. Fredrik , 1979

	The Ordovician sedimentary sequence on Smøla, west central Norway.

;Norges geologiske undersøkelse;TIDSSKRIFTARTIKKEL;NGU; No.348;21-31 sider

Abstrakt:

Sediments on the island of Smøla have been remapped and found to be delimited by five major faults. A series of coarse conglomerates and siltstones, the Leirvik Formation (new name), of unknown age and source, is overlain by limestones of the Skjølberg Formation (new name) containing silicified gastropods and brachiopods along with the Bathyurid Province trilobite Goniotelina cf. broeggeri of Arenig-Llanvirn age. Two phases of igneous activity are associated with the sediments, an older basic phase of ?Llanvirn age, containing local pillow lavas, and a younger more acid phase of approximate Ashgill age. Faulting of assumed post-Devonian age is invoked to expalin the present relationship between sediments and surrounding magmatic rocks.

Gautneb, Håvard; Roberts, David , 1989

	Geology and petrochemistry of the Smøla-Hitra Batholith, Central Norway.

;Norges geologiske undersøkelse;TIDSSKRIFTARTIKKEL;NGU Bulletin; No.416;1-24 sider

Abstrakt:

The plutonic rocks which compose the Smøla-Hitra Batholith (SHB) cover an exposed area of c.1000 km² and intrude folded, Arenig-Llanvirn, low-grade meta-sedimentary and bimodal metavolcanic rocks and higher-grade polydeformed gneisses of probable Proterozoic age. The SHB is unconformably overlain by Old Red Sandstone sediments of possible Late Silurian to definite Middle Devonian age. Field relations demonstrate that the oldest rock-types in the batholith comprise gabbro, monzodiorite and hornblende diorite. These are succeeded by tonalite, granodiorite and granite, which occur both as plutons and as abundant dykes and veins. Later members of the SHB include composite dykes, porphyritic microdiorite, appinitic pipe-like bodies, dolerite dykes and lastly, granophyre dykes. The hypabyssal rocks post-date a phase of weak, heterogeneous deformation manifested locally within the various plutons. Pressure estimates from hornblende compositions indicate a pressure of solidification of 0.26 +-0.1 GPa, corresponding to a depth of about 9 km. Preliminary isotopic dating has indicated an age range from c. 450 to c. 428 MA; latest Mid-Ordovician to Early Silurian. The rocks of the SHB show little sign of the Scandian deformation and metamorphism which are so common elsewhere in this part of Norway.

Fediuk, F. , 1975

	Smøla. Berggrunnskart; Smøla; 13211; 1:50 000; trykt i farger; NGU Skrifter nr.19

;Norges geologiske undersøkelse;KART

Fediuk, Ferry; Siedlecki, Stanislaw , 1977

	Smøla. Beskrivelse til det berggrunnsgeologiske kart 1321 I - 1:50 000 (med fargetrykt kart).

;Norges geologiske undersøkelse;TIDSSKRIFTARTIKKEL; KARTBESKRIVELSE;NGU; Skrifter; No.330; 19;1-23 + ka sider

Abstrakt:

An account is given of the general geology of Smøla and neighbouring islands, with special emphasis laid on the petrology of the various rock-types. The rocks within the map area comprise orthogneisses, paragneisses and migmatites of assumes Precambrian age; Ordovician supracrustal including both a fossili-ferous sedimentary and a volcanic series; and plutonic rocks ranging from ultramafites to granodiorites which are of probable Caledonian age. Major element chemical analyses are presented of 42 intrusive and extrusive igneous rocks. The youngest rocks in the area are represented by Devonian molasse-type conglomerates and sandstones. In the last part of the description some details are given of superficial deposits, mineral occurences and economic geology, as well as an outline of the sequence of structural events from Precambrian to Devonian time.

Holtedahl, Olaf , 1915

	V. Fossiler fra Smølen

;Norges geologiske undersøkelse;TIDSSKRIFTARTIKKEL;NGU; No.69;14 sider

Abstrakt:

Forkortet: In the following the author describes a few fossils from a limestone of a some- what crystalline character from the island of Smøla. Fossils are very rarely found in this part of Norway, on account of the metamorphism that the rocks have undergone. The general geology of Smøla has recently been investigated by several Norwegian geologists, and two papers dealing with this subject - by J. Schetelig and H. Reusch: see p.3 - have been published of late. As regards fossils, only a few tiny fragments, - probably cystoid or crinoid stems besides a problematical Halysites and a single section of what is likely to be a gastropod, - have been found, the material being quite insufficient for any conclusions as to age. In the early part of the summer 1914, during a short visit paid to this occurrence of limestone for practical purposes, the author happened to find some fragments of silicified fossils weathered out on the surface of the rock, and on further treating some pieces of the limestone with hydrochloric acid, he succeeded in isolating the forms described below. Stromatopora sp. Fig.1 On the surface of the weatherworn limestone-rocks the cross section of large, slightly domed masses, with a prominent concentric structure were observed in several places.

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