RECONSTRUCTION OF TECTONIC EVENTS IN SOUTHERN TAIMYR, ARCTIC RUSSIA, BASED ON PROVENANCE U-PB DETRITAL ZIRCON INVESTIGATIONS OF LATE PALEOZOIC TO MESOZOIC SEDIMENTS

LA-ICP-MS U-Pb analyses of about 4800 detrital zircon grains from 36 sandstones in southern Taimyr provide insight of late Paleozoic to Mesozoic sediment provenance and regional tectonic evolution. One lower late Carboniferous sample is dominated by Paleoproterozoic zircon derived from Siberian crystalline basement. Samples from upper late Carboniferous to late Permian have major 260-350 Ma and 470-650 Ma peaks, in addition to 420-460 Ma and 700-1000 Ma peaks, consistent with derivation from the Uralian orogen and Taimyr. The change in provenance from the Siberian craton in the SE to the Ural Mountains in the north suggests that late Paleozoic Uralian orogeny extended across Taimyr in the late Carboniferous. Triassic samples have a similar provenance, containing 260-355 Ma, 410-650 Ma and minor Neoproterozoic 700-1000 Ma zircons, in addition to a distinctive 220-260 Ma population likely derived from Siberian Trap-related magmatism in Taimyr. The common occurrence of 1000-1500 Ma zircons in all Triassic samples indicates the arrival of detritus from Baltica at this time. Jurassic samples have a different provenance defined by a single dominant age peak at 255 Ma and a distinct reduction in Permo-Carboniferous and Precambrian to early Devonian input, suggesting that erosion and input from Uralian sources had ceased while greater input from the Siberian trap-related rocks of Taimyr occurred, possibly the result of Mesozoic transpression in Taimyr.

Comparison of our results to published and unpublished results reveal that Permian detritus from the Urals was deposited in Novaya Zemlya, Taimyr, and the New Siberian Islands, but not in Chukotka or on Wrangel Island. In the Triassic, Taimyr, New Siberian Islands, Chukotka, Wrangel Island, Kular Dome, Lisburne Hills, Sverdrup Basin and Svalbard shared sources from Taimyr, Siberian Traps and the Urals, indicating that these places separated at present were close to each other or belonged to the same drainage system before the opening of the Amerasia Basin. The widespread distribution of material eroded from Taimyr and the Urals may be due to uplift resulting from Siberian trap magmatism. In the Jurassic, the restricted distribution of detritus from Taimyr and the Urals was likely controlled by Triassic rifting or related to the later opening of the Amerasia Basin.