Age of granitoids in the Pripechora fault zone of the basement of Pechora Basin: First U–Pb (SIMS) data

Resumo

Upper Precambrian basement of the Pechora Basin that is located between the Urals and Timan and is a part of the Pechora plate lies beneath 1–7 km of Ordovician-Cenozoic sediment cover. On the base of geophysical data and drilling the basement of the Pechora plate is subdivided into the Timan crustal block and the Bolshezemel crustal block which differ by composition and the character of magmatism. The boundary between the crustal blocks is a system of deep faults called the Pripechora and Ilych-Chikshino faults that strike in a northwestern direction, extending from the Urals to the Pechora Sea. Granitoids of Charkayu complex which were penetrated by several deep boreholes in Pripechora fault zone are interpreted as suprasubduction (island arc and collision) magmas associated with the Timan orogeny. First U–Pb dating (SIMS, using SHRIMP-II and SHRIMP-RG) of zircons from granitoids indicate that granitoid magmatism which accompanied the final stages of the Timanide orogeny occurred in the Late Vendian about 555–544 Ma. The age of zircons from granites of the 1-Charkayu borehole is 544 ± 6 Ma, from granites of 1-East Charkayu borehole is 545 ± 5 Ma, and from granodiorites of 1-South Charkayu borehole is 555 ± 2 Ma.