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Chemostratigraphy and heavy mineral assemblages as correlation tools for the Triassic Skagerrak Formation of the Central Graben in the Central North Sea

The Triassic Skagerrak Formation in the Central Graben of the North Sea is a fluvial-lacustrine succession that is historically difficult to subdivide in the subsurface into lithostratigraphic units, and to correlate between different wells and licence blocks. The formation consists of various sandstone members interspersed by mudstone members with relatively poor age constraints. Raman spectroscopy of heavy minerals in combination with chemostratigraphy is an effective tool to identify lithological differences and to reconstruct provenance of the individual members. The lower parts of the Skagerrak Formation (Judy Sandstone Member) are generally characterised by ultra-stable heavy mineral assemblages, indicating multi-recycling of nearby Palaeozoic cover units, while the directly underlying Bunter Sandstone additionally has several unstable mafic heavy mineral species, probably derived from local basement highs (e.g., Forties Montrose High). Up-section within the lower parts of the Joanne Sandstone Member there is a switch to more immature apatite-rich heavy mineral assemblages, likely related to a source change to Fennoscandian basement at the Norwegian margin. A mafic marker horizon within the upper Joanne Sandstone indicates input from contemporaneous volcanism at the Carnian-Norian boundary, and may represent a significant basin-wide unconformity.

Details

Author
H. Tim Breitfeld1, Brenton Fairey2, Juliane Hennig-Breitfeld1, Tim Pearce2, John Martin2
Institutionen
1TU Bergakademie Freiberg, Germany; 2Chemostrat Ltd., UK
Veranstaltung
GeoSaxonia 2024
Datum
2024
DOI
10.48380/pfh7-5y47
Geolocation
Europe