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CSPG Bulletin

Abstract


Bulletin of Canadian Petroleum Geology
Vol. 46 (1998), No. 1. (March), Pages 1-11

Sedimentology, Palynostratigraphy, Previous HitPalynofaciesNext Hit and Thermal Maturity of Upper Permian Rocks of Kolguyev Island, Barents Sea, Russia

M. Grigoriev, J. Utting

ABSTRACT

The Upper Permian succession of Kolguyev Island contains five transgressive-regressive sequences. Depositional environments, determined from sedimentological data and Previous HitpalynofaciesNext Hit, include coastal plain, estuarine, deltaic and beach, shoreface and shelf. The maximum depth of the shelf probably did not exceed 50 metres (slightly below the storm wave base). Sediment was derived from a nearby land mass.

Two informal palynomorph assemblage zones are recognized in the succession. The older, Assemblage I, based on comparisons with the pollen and spore zones of the Sverdrup Basin, Canadian Arctic Archipelago, is of Roadian (Ufimian?) age, and the younger, Assemblage II, is Wordian (Kazanian?) age. The floral province is Sub-Angara. The dominance and variety of trilete pteridophyte spores, suggests that the parent vegetation was diverse, such as may inhabit a swamp environment. The climate on land was probably seasonably humid.

The Thermal Alteration Index derived from spore colouration is low (TAI 2- or Ro% 0.45) and lies in the biogenic methane zone near the threshold of the "oil window". Source rock potential is low due to the scarcity of oil prone organic matter and the abundance of woody and coaly organic matter, and finely dispersed organic debris of mixed origin. The maximum depth of burial for the Upper Permian rocks (assuming a standard geothermal gradient) did not exceed 2 km.

RESUME

La succession du Permien superieur de l'ile de Kolguyev comporte cinq sequences transgressives-regressives. Les environments de depot, determines d'apres des donnees sedimentologiques et de Previous HitpalynofaciesTop, incluent ceux de plaine cotiere, estuarien, deltaique et de plage, littoral et de plate-forme. La profondeur maximale de la plate-forme n'etait probablement pas de plus de 50 metres (legerement sous le niveau de base des vagues de tempetes). Les sediments furent derives d'une masse de terre voisine.

Deux zones informelles d'assemblage de palynomorphes sont reconnues dans la succession. Le plus ancien, ou assemblage I, base sur des comparaisons avec les zones de pollens et de spores du bassin de Sverdrup, de l'archipel arctique canadien, est d'age Roadien (Ufimien?), et le plus jeune, ou assemblage II, est d'age Wordien (Kazanien?). La province florale est Sub-Angara. La dominance et la diversite des spores pteridophyte trilete suggerent que la vegetation mere etait diversifiee, comme celle qui peut habiter un environnement de marais. Le climat sur terre etait probablement humide en saison.

L'indice d'alteration thermique (TAI) derive de la coloration des spores est bas (TAI 2 ou Ro% 0,45) et se trouve dans la zone de methane biogenique, pres du seuil de la "fenetre a petrole, et de par l'abondance de matiere organique ligneuse et charbonneuse et de debris organiques disperses d'origines diverses. La profondeur maximale d'enfouissement de ces roches du Permien superieur (en presumant un gradient geothermal standard) n'a pas excede 2 km.

Traduit par Lynn Gagnon.

1 This paper is a contribution to the Canadian-Russian agreement on co-operation in the Arctic and the north (Theme 1).

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