Cristin-resultat-ID: 1771155
Sist endret: 13. januar 2020, 10:30
Resultat
Vitenskapelig foredrag
2020

Towards a revised stratigraphic framework for the Triassic in the Norwegian Barents Sea

Bidragsytere:
  • Christian Haug Eide
  • Valentina Marzia Rossi
  • Albina Gilmullina
  • Niall William Paterson
  • Tore Grane Klausen
  • Bjørn Anders lundschien
  • mfl.

Presentasjon

Navn på arrangementet: Nordic Geological Winter Meeting
Sted: Oslo
Dato fra: 8. januar 2020
Dato til: 10. januar 2020

Arrangør:

Arrangørnavn: NGF

Om resultatet

Vitenskapelig foredrag
Publiseringsår: 2020

Beskrivelse Beskrivelse

Tittel

Towards a revised stratigraphic framework for the Triassic in the Norwegian Barents Sea

Sammendrag

This contribution outlines a proposal for a revised stratigraphic framework for the Triassic in the Norwegian Barents Sea, where we present the working draft and invite audience and users to provide feedback before the new stratigraphic framework is formalized. The current stratigraphic scheme in the Triassic of the Barents Sea was originally created by Worsley et al. (1988), based on a series of wells from the Hammerfest Basin available at the time. Since then, more than one hundred new wells have been drilled in the Norwegian Barents Sea, and a dense grid of high-resolution 2D seismic lines covers the area. Because of this large volume of data and more than 30 years of continuing research, the understanding of the Triassic deposits has evolved greatly. A primary concern with the existing stratigraphic framework is that it does not describe and create order in the lithologies in the basin, it rather consists of a set of chronostratigraphic prograding clastic wedges. This creates a set of problems: (1) the understanding of the lithology in the basin is not reflected in the existing stratigraphic framework, (2) current formation names give little more information than the stratigraphic ages, (3) the existing stratigraphic framework creates ambiguity when communicating expected lithologies of drilling targets, and (4) one often has to wait for biostratigraphy to determine which formations have been drilled. The existing stratigraphic framework also does not include several formations now proved to be present in the basin (such as Early Triassic conglomerates on the Loppa High, Induan coarse-grained sandstones along the Northern Norwegian coast, and an organic rich shale just above the Permian-Triassic boundary across the basin), and does not include the basin-wide unconformity above the Fruholmen Formation. In 2018, the Norwegian Petroleum Directorate initiated a project to refine the lithostratigraphy of the Triassic of the Norwegian Barents Sea. The revised stratigraphy (1) should be based on lithology of the deposits, (2) should be simple to use and work on seismic data, well logs and core, (3) should retain names for the established reservoir units where possible, (4) should have a structure where groups reflect the large lithological changes across the basin, (5) should be a compilation of existing data, not a reanalysis, and (6) should be complimentary to the lithostratigraphic scheme used on Svalbard. The revised stratigraphy should also contain a set of figures that explain the current understanding of distribution of lithologies in the basin. In this contribution, we propose a revised stratigraphic framework that fulfils the aims stated above, and we ask for input from the audience to improve this draft. The main changes include: (1) clinoformal mudstones which were previously part of the prograding clinoformal units (Havert, Klappmyss Kobbe, Snadd and Fruholmen) are now assigned to the Tschermakfjellet Formation, (2) the formation names of the topset deposits of the prograding clinoformal units are retained, (3) the topset of the existing Snadd formation is split into two formations at the middle Carnian flooding surface, and the upper formation is termed the DeGeerdalen Formation, (4) several previously unknown formations are now included, (5) the Subgroup-division is abandoned and (6) the Rhaetian unconformity is now highlighted more clearly.

Bidragsytere

Christian Haug Eide

  • Tilknyttet:
    Forfatter
    ved Institutt for geovitenskap ved Universitetet i Bergen

Valentina Marzia Rossi

  • Tilknyttet:
    Forfatter
    ved Institutt for geovitenskap ved Universitetet i Bergen

Albina Gilmullina

  • Tilknyttet:
    Forfatter
    ved Institutt for geovitenskap ved Universitetet i Bergen

Niall William Paterson

  • Tilknyttet:
    Forfatter
    ved Institutt for geovitenskap ved Universitetet i Bergen

Tore Grane Klausen

  • Tilknyttet:
    Forfatter
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