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Oslo Region LithostratigraphyHans Arne Nakrem, NHM/Geology

1. Presentation of the geology (stratigraphy)2. Presentation (demo) of the web site

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Langesund

Mjsa

Blue: SilurianGreen: Cambrian andOrdoviciumViolet/red: Magmatics

Preserved as a result of east-west extension and grabenformation in Carboniferous-Permian time.

Oslo GrabenOslo Rift

Oslo

Illustration:NGU 2004

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sedimentation, different aspects of

stratigraphy, tectonics, basin evolution and magmatic processes.

Academic andindustry orientedexcursions.

The area may serveas a field laboratorywhere one canstudy:

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Norwegian Geological Survey

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The rocks continue south inSkagerrak and drillings in e.g.

the Farsund Basin haverevealed typical Oslo Cambro -Silurian fossils

Oslo Graben Off-shore

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The Cambro-Silurian rocks are mainly marine shales, sandstones andlimestones, with a rich, well studied fossil fauna (and micro flora).

Alum Shale Fm, black shale, Late Cambrian early Ordovician

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7/17Early Ordovician Tyen Fm, dark shale with graptolites

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Early Ordovician Huk Fm, limestone with abundant trilobites

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Lower Silurian Solvik Fm, shale and nodular limestones

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10/17Ringerike Group, deltaic red sandstone

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Lateral variations, Early Cambrian transgression from the north

Cambrian basal conglomerate

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Literature, lithostratigraphic definitions, Cambrian

The Cambrian was formally divided by Skjeseth in 1963, but recentwork on Cambrian stratigraphy (J. P. Nystuen et al.) should result inrefinement.

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The current lithostratigraphy is

defined for the Ordovician byOwen et. al. (1990)

Literature, lithostratigraphic definitions, Ordovician

Megistaspis maximus Norways largest trilobite

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Literature, lithostratigraphic definitions, Carboniferous

The Asker Group was named by Dons and Gyry (1967), but the unit names hadbeen used, unpublished, by Henningsmoen. Henningsmoen (1978) improved thedescription, but formal type localities were not stated.

Mainly fresh- andbrackish water fossils.Limestones withmarine fossils, likefusulinids andconodonts

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Interactive web-based lithostratigraphic lexicon

Unit name Unit status (hierarchic) (Group, Formation a.s.o.)

Unit validity (synonyms etc.) Age Area (distribution) Type locality Map grid reference (UTM) Municipality

Reference (author(s), page(s))Linked:

Lithostratigraphic log (image)Type locality (photo)Map (drawing)

The database fields (structure), contain so far information about:

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Some field work is / will be carried out Preservation status of localities Correlation tool? Biostratigraphic units? Map co-ordinates, select from?

More geological maps (NGU)? Link to Fossils from the Oslo Region

Interactive web-based lithostratigraphic lexicon

Web demonstration

To be considered:

Remember thislocality?Brggers mapfrom 1887