Results of U-Pb LA-ICP-MS dating of detrital zircons from Ediacaran-Early Cambrian deposits of the eastern part of the Baltic monoclise

摘要

Here we present the results of U-Pb LA-ICP-MS dating of detrital zircons from the Ediacaran-Early Cambrian deposits of the eastern part of the Baltic monoclise (Leningrad Region). The obtained age spectra of the detrital zircons suggest that, in the Ediacaran-Early Cambrian, the main clastic material source to the northwest of the Russian Platform was the Baltic Shield. Then in the Early Cambrian along with the Baltic Shield provenance, a clastic source from the Timanian margin of Baltica (northeast in modern coordinates) contributed to the deposits. The obtained data either somewhat set limits of the Timanian orogen formation as older than the previously suggested Middle Cambrian (about 510 Ma), based on the "absence of a Proto-Uralian-Timanian provenance signal" in the Sablino Formation rocks in the south Ladoga, or suggest another rearrangement of detritus transportation paths at the end of Stage 3 (Atdabanian).