DETRITAL ZIRCON (U-TH)/HE AGES FROM PALEOZOIC STRATA OF THE RUSSIAN HIGH ARCTIC RECORD MULTIPLE EPISODES OF PALEOZOIC TECTONIC EVOLUTION
The ZHe ages from Severnaya Zemlya samples indicate two distinct source regions for the Ordovician-Silurian and Devonian clastics. The ZHe detrital zircon ages from Ordovician- Silurian strata show a main peak at ca. 465 Ma. This suggests that the Ordovician and Silurian deposits were sourced mainly from the regions affected by the Caledonian orogeny. Consequently, the Caledonian Orogen and/ or deformation front could have potentially continued within a large portion of Barents Sea shelf and may have extended farther north (modern orientation). In contrast to older clastic rocks, ZHe ages from the Devonian deposits are grouped into two main age peaks: at ca. 375 Ma and 416 Ma. The ZHe ages suggest considerable uplift (minimum of 6-8 km) in the source area. We suggest that the 375 Ma event revealed from the ZHe data is likely correlated with the Ellesmerian Orogeny or the latest stages of the Caledonian (Svalbardian event) Orogen.
ZHe ages from the Cambrian-Ordovician strata of the De Long Islands have a primary age peak at ca. 383 Ma pointing to a significant uplift in the Late Devonian. We correlate the timing of exhumation with the Ellesmerian or the latest stages of the Caledonian Orogeny. These data provide important new insights into the Early-Middle Paleozoic history of the Arctic and the tectonic configurations of the Arctic region prior to the opening of the Meso-Cenozoic oceanic basins.
This research was supported by RFBR grant 16-55-20012 & The Research Council of Norway grant 254962/H30.