Radiometric dating of Precambrian rocks in Småland, southeastern Sweden

Åberg, Göran; Persson, Lars

doi:10.1080/11035898509454657

Cited by 35 publications

(3 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The shift has to postdate the isochron age, a minimum age for the overprint shifting the isochron is given by the biotite K-Ar age of about 1760Ma-1790Ma (Haudenschild 1988b). Weather the 1875Ma whole-rock age can be considered to represent a geological event or is caused by rotation of the isochron as described by Åberg and Persson (1984) cannot be answered definitively. After Van Schmus and Bickford (in: Åberg and Persson 1984) a rotation up to 20% away from the original age is possible, still giving a good fit of all samples.…”

Section: Rb-sr Whole-rock Agesmentioning

confidence: 99%

Cooling history of the eastern Svecokarelides: whole-rock and mica Rb-Sr and hornblende K-Ar ages in the areas of Pihtipudas-Iisalmi and Joroinen-Sulkava, Finland

Haudenschild¹

1990

Bull Geol Soc Finland

View full text Add to dashboard Cite

HAUDENSCHILD, UELI, 1990. Cooling history of the eastern Svecokarelides: whole-rock and mica Rb-Sr and hornblende K-Ar ages in the areas of Finland. Bull. Geol. Soc. Finland, 62, Part 1, Rb-Sr age determination on mica and whole-rock samples and K-Ar age determination on hornblendes were carried out to get information on the time of metamorphism and early cooling in two Proterozic areas of the Finnish Svecokarelides. In the Joroinen-Sulkava area (southern Finland) a whole-rock isochron of 1812 + 45Ma on metapelitic gneisses reflects the time of amphibolite-facies metamorphism. A 1875 + 17Ma whole-rock isochron on a quartz-diorite of the granulite-facies Pielavesi area (central Finland) may date an earlier high-grade metamorphic event, the low 87Sr/86Sr initial ratio of 0.7018 can be explained only by a shift or rotation of the isochron postdating its age. The disturbation of the whole-rock system could be related to the 1800-1820Ma metamorphism dated in the Joroinen-Sulkava area. A lower limit for the age of the isochron-shift is given by 1750-1790Ma biotite ages. The 1800-1820Ma metamorphic event seems to have been weaker in central than in southern Finland while the 1875Ma metamorphism seen in central Finland (Pielavesi) is absent or completely overprinted in the south.Muscovite Rb-Sr and hornblende K-Ar ages date the cooling of the areas to about 500°C. Muscovite ages vary between 1730Ma and 1770Ma for different localities. Five fractions of two hornblende samples define an isochron of 1778Ma on the 40Ar/36Ar versus 40K/36Ar diagram. In one locality (Vieremä) the hornblende ages (1995-2143Ma) are remarkably higher than the age of the muscovite (1828Ma). The hornblende ages were interpreted as having a pre-metamorphic memory, being of Jatulian or late Archean origin. The blocking-temperature for argon in horblende therefore should be somewhat higher than the blocking-temperature of muscovite in respect to the Rb-Sr system.

show abstract

Section: Rb-sr Whole-rock Agesmentioning

confidence: 99%

Cooling history of the eastern Svecokarelides: whole-rock and mica Rb-Sr and hornblende K-Ar ages in the areas of Pihtipudas-Iisalmi and Joroinen-Sulkava, Finland

Haudenschild¹

1990

Bull Geol Soc Finland

View full text Add to dashboard Cite

show abstract

“…The temporal relationships between the OJB and presumed younger TIB 1 magmatism have long been confused by a U-Pb zircon age of ~1.84 Ga for a volcanic TIB rock at Storebro (Åberg & Persson 1984). However, this result was based on discordant fractions that lie along a reference line with an inexplicable lower intercept of ~714 Ma.…”

Section: Constraints For Ojb and Tib Magmatismmentioning

confidence: 73%

Transitioning from Svecofennian to Transcandinavian Igneous Belt (TIB) magmatism in SE Sweden: Implications from the 1.82 Ga Eksjö tonalite

Åhäll¹,

Connelly

Brewer

2002

GFF

View full text Add to dashboard Cite

“…During the regional reconnaissance mapping, several occurrences were found of intensely sheared rocks belonging to the SmAland granitoids and the Smaland volcanites. The SmAland volcanites are also referred to as the younger volcanites and are thought to be slightly older than the granitoids (Aberg & Persson 1984;Persson & Wikman 1986). The geographic locations of some of these sheared rocks suggest that they may be interpreted as forming the continuation of the Nyatorp Shear Zone, which thus extends for at least 50 km from Lake orken in the west t o north of FAgelfors in the east (Fig.…”

mentioning

confidence: 98%

Microstructures in the Nyatorp Shear Zone, southeastern Sweden

Skjernaa

1992

Geologiska Föreningen i Stockholm Förhandlingar

View full text Add to dashboard Cite

Radiometric dating of Precambrian rocks in Småland, southeastern Sweden

Cited by 35 publications

References 9 publications

Cooling history of the eastern Svecokarelides: whole-rock and mica Rb-Sr and hornblende K-Ar ages in the areas of Pihtipudas-Iisalmi and Joroinen-Sulkava, Finland

Cooling history of the eastern Svecokarelides: whole-rock and mica Rb-Sr and hornblende K-Ar ages in the areas of Pihtipudas-Iisalmi and Joroinen-Sulkava, Finland

Transitioning from Svecofennian to Transcandinavian Igneous Belt (TIB) magmatism in SE Sweden: Implications from the 1.82 Ga Eksjö tonalite

Microstructures in the Nyatorp Shear Zone, southeastern Sweden

Contact Info

Product

Resources

About