TitleDepositional conditions and petroleum potential of the Middle Triassic Passhatten Member (Bravaisberget Formation), Spitsbergen
Journal titlePolish Polar Research
KeywordsArctic ; Spitsbergen ; Middle Triassic ; Bravaisberget Formation ; depositional conditions ; organic carbon ; petroleum potential
Divisions of PASNauki o Ziemi
AbstractThe Passhatten Member (Anisian–Ladinian) is the most westward exposure of the Middle Triassic sedimentary sequence of Spitsbergen. The member has an average organic carbon of 2.21 wt %. The sediments were deposited in a shallow shelf environment under conditions of high biological productivity stimulated by a well−developed upwelling system and an enhanced nutrient supply from land areas. The high biological productivity caused a high supply of organic particles to the shelf bottom. Decomposition of organic matter initiated oxygen deficiency in the bottom waters; however, bottom water dynamics on the shallow shelf temporarily replenished the oxygen. Consequently, the Passhatten Mb section is bioturbated, even in thick black shale horizons and consists of alternately spaced lithological layers with variable organic carbon content. The organic matter is dominated by type II kerogen with a mixture of strongly altered marine and/or land derived organic matter. Calculated initial hydrogen index values suggest oil−prone organic matter similar to kerogen I and II types. The organic matter is in the upper intermediate stage of thermo−catalytic alteration, close to the cata− and metagenetic boundary. Maturity indicators including Rock−Eval, Maximum Temperature, Organic Matter Transformation Ratio, Residual Carbon content, as well as the volume of methane generated suggest mature to overmature organic matter. Methane potential retained in the black shales sequence is significant. Unexpelled gas is estimated at 395 mcf/ac−ft for the examined section.
PublisherPolish Academy of Sciences ; Committee on Polar Research
TypeArtykuły / Articles
IdentifierISSN 0138-0338 ; eISSN 2081-8262