THE AGE AND REGIONAL CORRELATION OF THE SVECOFENNIAN GEITFJELL GRANITE, VESTRANDEN, NORWAY

Citation
L. Johansson et al., THE AGE AND REGIONAL CORRELATION OF THE SVECOFENNIAN GEITFJELL GRANITE, VESTRANDEN, NORWAY, Norsk geologisk tidsskrift, 73(2), 1993, pp. 133-143
Citations number
62
Categorie Soggetti
Geology
Journal title
Norsk geologisk tidsskrift
ISSN journal
0029196X → ACNP
Volume
73
Issue
2
Year of publication
1993
Pages
133 - 143
Database
ISI
SICI code
0029-196X(1993)73:2<133:TAARCO>2.0.ZU;2-O
Abstract
U-Pb zircon dating of granitoids from the northermost part of the West ern Gneiss Region (Vestranden) has yielded the oldest ages so far reco rded in central and southern Norway. The Geitfjell granite, a coarse-g rained granite near Grong, central Norway yielded a U-Pb zircon age of 1828(-65)+88 Ma, whereas a Rb-Sr determination yielded an age of 1770 +/-62 Ma. Its initial Sr-86/Sr-87 is 0.7094 and epsilon(Nd) (1830 Ma) value is -0.04. Petrographically similar granites occur also in large areas in the northern half of the Vestranden region. The petrography, isotope chemistry, age and chemical composition of dhe Geitfjell grani te closely resembles that of granites of the Revsund type, which intru de marine metasedimentary rocks in the Svecofennian Bothnian Basin in north-central Sweden. A correlation of these granites is thus suggeste d. The occurrence of this type of granite in the northernmost part of the Western Gneiss Region suggests that this region reports the wester ly continuation of the Svecofennian Bothnian Basin rather than a part of the Southwest Scandinavian orogenic province or the Transscandinavi an Granite Belt. Precambrian metasedimentary rocks of Bothnian Basin a ffinity may thus occur in Vestranden.