The Permian/Triassic evolution of the Timan-Pechora and Barents Sea Basins

Permian / Triass overgangen, omtrent 250 millioner år siden, preges av den største massedødeligheten av marine og jordbaserte biota i jordhistorien. Det er en voksende vitenskapelig konsensus om at denne biotiske krisen var knyttet til en store vulkanutbrudd, de sibiriske LIP. Imidlertid er det direkte begrenset bevis for årsakssammenheng mellom de vulkanske suksessene i Sibir og de marine og jordiske utryddelsesarrangementene. I samarbeid med VNIIOkeangeologia i St Petersburg ble steinprøver fra 4 kjerner i Timan Pechora-bassenget med Permian-Triassic-grensen analysert for palynofacier, deponeringsmiljø og biostratigrafisk alder / karbonisotopstratigrafi. Permian Triassic-overgangen ble også studert i Finnmark-plattformskjernene 7128/12-U-01 for høyoppløselig biostratigrafi (basert på palynologi) og kjemostratigrafi basert på karbonisotoper av organiske biomarkører (n-alkaner). Biomarkøranalysen tillater separasjon av det terrestriske fra den marine komponenten av karbonisotop-sammensetningen av sedimentært organisk materiale.

Late Permian-Early Triassic times cover an important phase in the Barents Sea basin evolution. It is characterized by regional subsidence marking an end to Late Carboniferous-Early Permian carbonate deposition and the large accommodation space formed was filled by prograding siliciclastic systems mainly sourced from the uplifted Urals in the southeast. The project is a new Norwegian-British-Russian joint venture with the aim to improve our understanding of the processes behind this important phase in the regional basin evolution, we need better constraints on their timing, causes and implications. Key topics to be addressed include: 1) When was the onset of the regional subsidence (mid-Permian or towards end Permian)? 2) Are there any relationships to the Siberian Traps which formed at the Permian-Triassic transition? 3) What caused this regional subsidence and how did these processes affect the temperature history of the basin? Exploration success in the Central Barents Sea may be dependent on petroleum system(s) of Triassic age. Triassic source rocks are proven in the parts of the western Barents Sea - what about farther east? Finding good reservoir sands in the Triassic prograding system has so far been a challenge in the western Barents Sea - is the system more sand-prone farther east? We suggest to establish a fine resolution correlation of PTB interval from the Norwegian sector eastwards to the Russian continental shelf including the Ural region by using an integrated approach combining palyno -, C-isotope -, cyclo - and seismic sequence stratigraphy. The generated stratigraphic, palaeoenvironmental and palaeogeographic data will be used in geophysical models that simulate the tectonic and thermal evolution of the sedimentary basins and evaluate t heir hydrocarbon resource potential.