Results of U-Pb (LA-ICP-MS) dating of detrital zircons from terrigenous rocks of the Upper Precambrian basement of the Obdyr Uplift (Middle Timan)

The Kanin-Timan Ridge is formed by a chain of disjointed tectonic blocks of the Upper Precambrian basement, exposed at the surface or underlying a cover of Silurian-Cenozoic sediments and representing fragments of the extended Timanian passive margin of Baltica, which formed in the Middle(?)-Late Riphean. The results of U-Pb (LA-ICP-MS) isotope dating of detrital zircon grains from the Upper Precambrian sandstones of the Obdyrskaya Series of the Obdyr Uplift (southern part of the Middle Timan) were compared with published U-Pb data on detrital zircons from similar in age terrigenous rocks of other blocks of the Kanin-Timan Ridge. The zircon age spectra, which characterise the rocks of the northwestern and southeastern (in modern coordinates) parts of the ridge, and, consequently, the sources of clastic material, which supplied detrital zircons to the terrigenous rocks of the Timanian margin of Baltica, differ significantly. The boundary between the erosion zones roughly corresponds to the axis of the Central Russian orogen, which jointed together the early Precambrian blocks of the East European Platform – Fennoscandia and Volga-Sarmatia –1.8–1.7 billion years ago. The northwestern part of the Timanian margin received a large amount of detrital material from the Fennoscandian block, while the terrigenous rocks of the southeastern part of this continental margin were probably formed with a significant contribution from eroded rocks of the Volga-Sarmatia.