Evolution of migmatitic granulite complexes; implications from Lapland granulite belt; Part II, Isotopic dating

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Authors:Tuisku, Pekka; Huhma, Hannu
Author Affiliations:Primary:
University of Oulu, Oulu, Finland
Volume Title:Bulletin of the Geological Society of Finland
Source:Bulletin of the Geological Society of Finland, 78(2), p.143-175. Publisher: Geological Society of Finland, Helsinki, Finland. ISSN: 0367-5211
Publication Date:2006
Note:In English. Accessed on July 31, 2007
Summary:The migmatitic metapelites of the Lapland granulite belt in the NE part of the Fennoscandian Shield represent an arc-related greywacke basin metamorphosed in the granulite facies. Detrital zircons from migmatitic metapelites are derived from 1940-2900 Ma old acid source rocks (U-Pb SIMS ages). The clustering of detrital zircon ages between 1970 and 2200 Ma is problematic, because abundant felsic crust of this age is absent in the shield. The metasediments are characterized by Sm-Nd model ages of ∼ 2300 Ma. A younger 1905-1880 Ma population of homogeneous zircons was formed during regional metamorphism. The peak high-grade metamorphism took place at ∼ 1900 Ma; the latest chronlogical record from later decompression and cooling is from ∼1850 Ma. The norite-enderbite series of these Lapland granulites represents acid magmas intruded in the metasediments at ∼ 1920-1905 Ma, and were probably an important heat source for metamorphism. Monazite U-Pb ages of migmaitic metasediments in the range 1906-1910 ± 3 Ma overlap the late stage of enderbite intrusion and growth of early metamorphic zircons. Garnet-whole-rock Sm-Nd ages from leucosomes in the range 1880-1886 ± 7 Ma are concurrent with the growth of the youngest metamorphic zircons. . [R.A.H.]
Sections:Age determination; Geochemistry; Petrology
Subsections:Metamorphism: regional, dynamic
Subjects:Absolute age; Complexes; Dates; Diorites; Enderbite; Gabbros; Genesis; Granulites; Igneous rocks; Metamorphic belts; Metamorphic rocks; Metapelite; Metasedimentary rocks; Migmatites; Norite; Paleoproterozoic; Plutonic rocks; Precambrian; Proterozoic; Sm/Nd; Tectonics; Tonalite; U/Pb; Upper Precambrian; Europe; Finland; Inari Finland; Lapland; Lapland Finland; Scandinavia; Western Europe; Kaarle Kustaa Finland; Kuttura Finland; Lapland granulite belt; Paktevarsavu Finland; Utsjoki Finland
Coordinates:N651500 N700500 E0300500 E0201500
Abstract Numbers:06M/4731
Record ID:2007077167
Copyright Information:GeoRef, Copyright 2020 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom, Reference includes data from FINGEO, Geological Survey of Finland
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