Paper No. 208-12
Presentation Time: 4:00 PM
DETRITAL ZIRCON (U-TH)/HE AGES FROM PALEOZOIC STRATA OF THE RUSSIAN HIGH ARCTIC RECORD MULTIPLE EPISODES OF PALEOZOIC TECTONIC EVOLUTION
ERSHOVA, Victoria, Institute of Earth Sciences, Saint Petersburg State University, University emb. 7-9, Saint Petersburg, 199034, PROKOPIEV, Andrei, Diamond and Precious Metal Geology Institute, Russian Academy of Sciences, 39 Lenin Avenue, Yakutsk, 677891, Russia, ANFINSON, Owen, Geology, Sonoma State University, Rohnert Park, CA 94928, KHUDOLEY, Andrey, Regional geology, Saint Petersburg State University, University emb. 7-9, Saint Petersburg, 199034, STOCKLI, Daniel F., Jackson School of Geosciences, The University of Texas at Austin, 2305 Speedway, Stop C1160, Austin, TX 78712, FALEIDE, Jan Inge, Department of Geosciences, University of Oslo, Oslo, 1047, Norway and GAINA, Carmen, Centre for Earth Evolution and Dynamics (CEED), University of Oslo, PO Box 1048, Blindern, Oslo, 0316, Norway, v.ershova@spbu.ru
Here we present detrital zircon (U-Th)/He (ZHe) ages for Paleozoic rocks from the Russian High Arctic – Severnaya Zemlya Archipelago and De Long Islands. Six samples from Paleozoic successions of the Severnaya Zemlya Archipelago were analyzed for ZHe and three samples from Cambrian-Ordovician successions of the De Long Islands were analyzed for detrital zircon ZHe analysis. The obtained ZHe ages for Severnaya Zemlaya rocks have not been reset since deposition, therefore they provide information on the exhumation history of the sediment source regions. The obtained ZHe ages for samples from the De Long Islands have been reset since deposition; they constrain the minimum burial depth of the studied succession to >~7 km and provide information on the exhumation history of the De Long Islands.
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.
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