U–Pb geochronology of bimodal magmatism in the Revsund suite, north central Sweden

Hellström, Fredrik; Hegardt, Eric Austin

doi:10.1080/11035890301254237

Cited by 3 publications

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“…2A), and therefore the two rocks must be contemporaneous (see Hellström & Austin Hegardt 2003; this issue). More enigmatic is the fact that some dykes of ʻgneiss-graniteʼ, according to Åhman (1967), cut and brecciate the gabbro massif.…”

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confidence: 97%

U–Pb zircon dating of the Hoting gabbro, north central Sweden

Hellström

Larson

2003

GFF

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The Hoting gabbro, located in the northern part of Jämtland County, is one of the largest layered mafic intrusions in Sweden. The rounded, main part of the intrusion has the shape of a funnel, in which the magmatic layering is concentrically developed with steeply dipping outer layers, and flat layering in the central part. The modal composition is dominated by plagioclase, where most samples classify as leucogabbro. SIMS U-Pb zircon data give a concordia age of 1786±10 Ma (2σ), interpreted to date the emplacement of the Hoting gabbro, which thus took place contemporaneously with emplacement of the Revsund granitoid suite. The latter can be considered to belong to the main phase of the Transscandinavian Igneous Belt. A ʻRevsund ageʼ is also supported by some field relationships, indicating that melts of Revsund granite and gabbro coexisted. Three highly discordant analyses define the lower intercept of the regression line in the concordia diagram to an age of 453±19 Ma. This age corresponds in time with the Scandian period of Caledonian orogenic activity and is suggested to represent an episodic leaching of Pb from metamict zircon domains.

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confidence: 97%

U–Pb zircon dating of the Hoting gabbro, north central Sweden

Hellström

Larson

2003

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Implications of the emplacement age of the Kläppsjö gabbro; a mafic layered intrusion in the Bothnian basin, north central Sweden

Hellström

2004

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Chapter 4 Paleoproterozoic (2.0–1.8 Ga) syn-orogenic sedimentation, magmatism and mineralization in the Bothnia–Skellefteå lithotectonic unit, Svecokarelian orogen

Skyttä

Weihed

Högdahl

et al. 2020

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The Bothnia–Skellefteå lithotectonic unit is dominated by turbiditic wacke and argillite (Bothnian basin), deposited at 1.96 (or older)–1.86 Ga, metamorphosed generally under high-grade conditions and intruded by successive plutonic suites at 1.95–1.93, 1.90–1.88, 1.87–1.85 and 1.81–1.76 Ga. In the northern part, low-grade and low-strain, 1.90–1.86 Ga predominantly magmatic rocks (the Skellefte–Arvidsjaur magmatic province) are enclosed by the basinal components. Subduction-related processes in intra-arc basin and magmatic arc settings, respectively, are inferred. Changes in the metamorphic grade and the relative timing of deformation and structural style across the magmatic province are linked to major shear zones trending roughly north–south and, close to the southern margin, WNW–ESE. Zones trending WNW–ESE and ENE–WSW dominate southwards. Slip along the north–south zones in an extensional setting initiated synchronously with magmatic activity at 1.90–1.88 Ga. Tectonic inversion steered by accretion to a craton to the east, involving crustal shortening, ductile strain and crustal melting, occurred at 1.88–1.85 Ga. Deformation along shear zones under lower-grade conditions continued at c. 1.8 Ga. Felsic volcanic rocks (1.90–1.88 Ga) host exhalative and replacement-type volcanogenic massive sulphide deposits (the metallogenic Skellefte district). Other deposits include orogenic Au, particularly along the ‘gold line’ SW of this district, porphyry Cu–Au–Mo, and magmatic Ni–Cu along the ‘nickel line’ SE of the ‘gold line’.

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U–Pb geochronology of bimodal magmatism in the Revsund suite, north central Sweden

Cited by 3 publications

References 3 publications

U–Pb zircon dating of the Hoting gabbro, north central Sweden

U–Pb zircon dating of the Hoting gabbro, north central Sweden

Implications of the emplacement age of the Kläppsjö gabbro; a mafic layered intrusion in the Bothnian basin, north central Sweden

Chapter 4 Paleoproterozoic (2.0–1.8 Ga) syn-orogenic sedimentation, magmatism and mineralization in the Bothnia–Skellefteå lithotectonic unit, Svecokarelian orogen

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