The Sources of the Clastic Material of the Terrigenous Sequences of the Neoarchean and Paleoproterozoic Paleobasins in the Eastern Part of the Fennoscandian Shield Based on Isotope Analysis Data for Detrital Zircons (SIMS, LA-ICP-MS)

Abstract

Isotope analyses of detrital zircons from the terrigenous sequences of the Neoarchean Uraguba–Titovka greenstone belt and the Paleoproterozoic Pechenga–Varzuga and Vetreny belts, including the basal conglomerates, by the SIMS (SHRIMP-II) and LA-ICP-MS methods were performed for the first time. On the basis of the data obtained, the inception dates of the structures and the ages and lithology of their basement rocks were established, and the origin of the terrigenous rocks was refined. Detrital zircon populations with ages of 2.66–2.73, 2.76–2.79, 2.82–2.87, and 2.98–3.00 Ga are predominant. The sources of these zircons were the rocks of the tonalite–trondhjemite–granodiorite complex, enderbites, high-alumina gneisses, and their metamorphosed varieties, which dominate the present-day erosion surface and have been penetrated by the Kola superdeep borehole. Zircon populations with the age of 3.00–3.70 Ga were also found. Zircon with the age of 3698 ± 8 Ga was found in terrigenous red beds, which mark the global Oxygen Revolution (2.2–2.3 Ga). Data obtained confirm a significant contribution of the Eoarchean and Paleoarchean material to continental crust composition in the region and the different inception dates of the Pechenga and Imandra–Varzuga structures.