Age and provenance of early Precambrian metasedimentary rocks in the Lapland–Kola Belt, Russia: evidence from Pb and Nd isotopic data

207Pb/206Pb ages are presented for detrital zircons (Laser Ablation Microprobe ICP‐MS) and whole‐rock Nd isotopic determinations (TIMS) from samples of Neoarchean and Palaeoproterozoic metasedimentary rocks from the Umba granulite terrane and the Keivy domain of the Central Kola composite terrane, Kola Peninsula, north‐western Russia. Three are samples of rocks from the Umba granulite terrane that were deposited ≈ 2.20–1.90 Ga; they contain Archaean detritus, much of it older than 3.0 Gyr, as well as abundant 2.20–1.95‐Gyr‐old material. Deposition may have occurred on the margin of an Archaean craton with an exposed Palaeoproterozoic magmatic arc source, possibly during orogenesis. Two samples from the Keivy domain have remarkably similar, dominantly Archaean detrital zircon age spectra. One was deposited pre‐2.4 Ga, whereas the other was probably deposited post‐2.01 Ga. Both had similar sources, compatible with the proximal country rocks, and possible shallow‐water (?) cratonic margin depositional settings.

[1]  D. J. Scott Geology, U – Pb, and Pb – Pb geochronology of the Lake Harbour area, southern Baffin Island: implications for the Paleoproterozoic tectonic evolution of northeastern Laurentia , 1997 .

[2]  Gilles Gauthier,et al.  Comparison of TIMS (U-Pb) and laser ablation microprobe ICP-MS (Pb) techniques for age determination of detrital zircons from Paleoproterozoic metasedimentary rocks from northeastern Laurentia, Canada, with tectonic implications , 1996 .

[3]  P. J. Patchett,et al.  Implications for the evolution of continental crust from Hf isotope systematics of Archean detrital zircons , 1990 .

[4]  P. Barbey,et al.  Petrogenesis and evolution of an early Proterozoic collisional orogenic belt: The granulite belt of Lapland and the Belomorides (Fennoscandia) , 1984 .

[5]  D. DePaolo Neodymium isotopes in the Colorado Front Range and crust–mantle evolution in the Proterozoic , 1981, Nature.

[6]  A. Nutman,et al.  U-Pb zircon ages of Kangâmiut dykes and detrital zircons in metasediments in the Palaeoproterozoic Nagssugtoqidian Orogen (West Greenland) Clues to the pre-collisional history of the orogen , 1999 .

[7]  J. Karhu,et al.  Field, petrophysical and carbon isotope studies on the Lapland Granulite Belt: implications for deep continental crust , 1996 .

[8]  Iurii D. Pushkarev Megacycles in the evolution of the crust-mantle system , 1990 .

[9]  P. Vidal,et al.  Isotopic data (UPb, RbSr, PbPb and SmNd) on mafic granulites from finnish lapland , 1984 .