--> --> Depositional Environments and Integrated Stratigraphy of the Upper Triassic Kapp Toscana Group on Svalbard and the Barents Sea Shelf, Norway
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Depositional Environments and Integrated Stratigraphy of the Upper Triassic Kapp Toscana Group on Svalbard and the Barents Sea Shelf, Norway

Abstract

The lateral equivalents of the Triassic reservoir rocks of the Barents Sea Shelf are well exposed to the north in Svalbard. Due to presence of hiatuses and lack of marine index fossils correlation with the international standard zonation is challenging. An understanding of the depositional environment and precise stratigraphic assignment is crucial for reservoir correlation. We describe the depositional environment of the deltaic succession of the Kapp Toscana Group from central Spitsbergen, Norway, by integrating Previous HitanalysisNext Hit of sedimentary organic matter with organic geochemical methods. Sixty outcrop samples were studied from two sections at Juvdalskampen and Botneheia from Spitsbergen where Upper Triassic sediments are exposed. Standard acid treatment procedures were used to extract the sedimentary organic matter and Rock-Eval and bulk organic carbon isotope values were measured. The samples yielded well preserved, but low abundance palynomorph assemblages dominated by terrestrial, type III palynodebris. A total of 7 assemblage zones were recognized based on changes in sedimentary organic matter and composition of palynomorphs. The lowermost Botneheia Fm is dominated by terrestrial Previous HitpalynofaciesTop and freshwater palynomorphs, while the Tschermakfjellet Fm above by terrestrial assemblages with marine influx. The overlying De Geerdalen Fm is composed entirely of terrestrial material and the uppermost Knorringfjellet Fm is terrestrially dominated with marine influx. Data integration suggested a mainly restricted, marine influenced, depositional environment during the deposition of the Botneheia Fm. The Tschermakfjellet Fm was deposited in a pro-delta environment with a maximum flooding surface close to the base, characterized by a maximum in marine sedimentary organic matter. The De Geerdalen Fm was deposited in a coastal or delta plain environment with influx of freshwater palynomorphs along with indications of establishment of local vegetation during a Highstand Systems Tract. The youngest Knorringfjellet Fm was deposited in a Transgressive Systems Tract as part of a new sequence cycle in a shallow marine environment. Age-indicative palynomorphs were used to successfully integrate the sections into the regional standard stratigraphic framework and correlate these sections with others from the Barents Sea. By using bulk carbon isotopes the sections can be correlated with a section close by at Vendomdalen and linked to the global geomagnetic polarity timescale.