Original paper

Stratigraphic Guide to the Rogaland Group, Norwegian North Sea

Brunstad, Harald; Gradstein, Felix; Lie, Jan Erik; Hammer, Øyvind; Munsterman, Dirk; Ogg, Gabi; Hollerbach, Michelle

Abstract

This guide provides a major revision and update of the lithostratigraphy of the Rogaland Group for the Norwegian North Sea. An abundance of recent well and seismic data sheds new light on lithology, biostratigraphy, provenance, geographic distribution and terminology of all Rogaland rock units, used widely in the search for oil and gas.

While finer siliciclastic units largely remain as previously defined, previous sandstone/siltstone formations and one (reworked) chalky unit are now re-defined. These lithostratigraphic units are local sediment bodies of a lithology different from the surrounding and embracing formation. Hence, these lithostratigraphic units are members in the formal stratigraphical hierarchy. With the new definitions and re-definitions the Rogaland Group now consists of four formations and 15 members, which span the stratigraphic interval from lower Paleocene to lower Eocene.

The revisions concerning the sandstone bodies are of four different types:

- Re-definition from formations to members

- Re-definition of lithological criteria

- Introduction of members long used already offshore England and Denmark

- Definition of new members

For those practicing geologists not familiar with historic precedence, an important `sine qua non' in (litho-) stratigraphy, it should be pointed out that 8 out of 15 members discussed here have been predefined in literature dealing with the UK and Danish sectors of the North Sea. The present study thus updates the Norwegian lithostratigraphic bulletins of the nineteen eighties for its offshore area. The internet site www.nhm2.uio.no/norlex provides an interactive digital version of this study, with links to well data, biozonations and core archives relevant to the Rogaland Group.