Erling I. Heintz Siggerud¹, Tina R. Olsen²
(1) SEPM, IAS, Lysaker, Norway
(2) SEPM, IAS, Stavanger, Norway

Abstract: Application of Ichnofabric Stacking pattern to high resolution sequence stratigraphy; case study from Jurassic Ness and Tarbert Formations, Norwegian sector, Northern North Sea

The identification of trace fossils, and ichnofabrics in particular, greatly improve our understanding of the palaeoenvironment at the time of deposition. In addition to the identification of palaeoenvironmental changes and important stratigraphic surfaces, the ichnofabric-staking pattern record the transgressive-regressive evolution of any depositional system. Applied within a high-resolution sequence stratigraphic framework, this is a powerful tool that enables a very detailed stratigraphic brake-down, far beyond the resolution of biostratigraphy on the scale of hydrocarbon fields.

This is illustrated in the case study based on cores from the Ness and Tarbert Formations of the Middle Jurassic Brent Group, in the Tampen Spur area, Norwegian sector, Northern North Sea, where regressive and transgressive tracts of non-marine and marginal marine deposits cannot be differentiated without the use of ichnology. These show that the transgressive tracts constitute the largest volumes of the successive transgressive-to-regressive sedimentary wedges of the Ness Formation in the studied area. Accordingly, pre-existing models suggesting that the transgressive phases is thin or absent within the Ness Formation deposits and that the regressive elements dominate over transgressive will have to be modified at least for the Tampen Spur area.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana