north sea marl våle – maureen nomenclature linkedin version

Lower Tertiary Lithostratigraphy in the Southern North Sea, Denmark, Norway & UK: Brief Notes for discussion. What Nomenclature?North Sea Marl? Or Maureen Formation? Or Våle Formation?

North Sea Marl: informal nomenclature from 1982, Danish sector.

Maureen Formation: formal nomenclature from UK sector, 1992, includes the equivalent of the Våle Formation = marly interval at base.

Upper part of Maureen Fm = Æbelø Clay of onshore Denmark.

Våle Formation: formal nomenclature from Norwegian sector, 1989. Marls with interbedded claystones, limestones,+ siltstone / sandstone stringers. Type well N1/3-1 (49m thick). =Kerteminde Marl onshore Denmark (& Lellinge Greensand Fm)

Offshore units nomenclature traditionaly kept separate from onshore nomenclature despite demonstrated identical nature of units in some instances ie. subdivision of the Lista Formation.

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Nomenclature: North Sea Marl? Or Maureen Formation? Or Våle Formation? Continued

Maureen Formation: terminated by a regional transgression with basin wide mud deposition – Cenodiscus Claystone.

Upper boundary of Maureen, Ty and Våle Formations: down hole change to dark grey silty mudstone from the overlying bioturbated green and or red tinted and commonly waxy shales at the base of the Lista Formation.

Boundary commonly depicted at base of a high gamma ray peak

Boundary is first downhole influx of Cenodiscus lenticularis.


First Step: Back to Basics – well data▪ In the first instance it is best to use the published formalised lithostratigraphical nomenclature whenever possible.

▪ Supplement with informal nomenclature if necessary; ie ’Intra Danian Marl’, and supported by a definition and data.

▪ This process gives a sound foundation upon which to build.

▪ Ensures a common understanding.

The North Sea Marl is formalised as the Våle Formation in the Danish sector (GEUS 2007) see following slides.


Revised Lithostratigraphical Framework of the Palaeogene in the Danish North SeaGeological Survey of Denmark and Greenland Bulletin 12, 2007

▪ New, revised and formalised lithostratigraphical nomenclature within the Rogaland Group.

▪ Seven formations containing eleven new members

▪ Using previously published lithostratigraphical schemes applied to the Danish sector at formation level; reference sections established.

▪ New members established from the Danish sector


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Formalised Nomenclature Danish Sector (2007)

Offshore Onshore

North Sea Marl is now termedVåle Formation

Major sequence boundary

Transgressive flooding eventFlood planktonic forams

Major sequence boundary/ event associated with regional and local tectonics, changes in environment, erosion and depositional regime

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Co-evality of North Sea Marl, Våle Formation and Maureen Formation (pars)


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Proximal(Shallow)

Distal(Deep)


Onshore the key to the offshore?

Typical Succession offshore Denmark

Offshore Danish wells show a typical succession of Våle Formation overlying Danian Ekofisk Formation chalks.

Does the location of the wells w/ respect to structural and sedimentological features within the Upper Cretaceous affect the sequences developed?

Which wells show a typical succession?


Typical Succession: lithology and key fossils

THANETIAN

Lista Formation: dark coloured, greyish – greenish or brownish, non-laminated to faintly laminated, non calcareous mudstone.

▪ Poorly fossiliferous.

▪ Radiolaria and impoverished agglutinating benthonic foraminifera.

SELANDIAN

North Sea Marl / Våle Formation: light grey to greenish grey pyrite bearing marls.

▪ Difficult base position as is often gradational with the Chalk. Basal Våle – light coloured marls.

▪ Highest occurrence of reappearance downhole of planktonic foraminifera in the Våle Fm.

▪ Highest occurrence of Alisocysta reticulata (dinoflagellate) at base.

▪ Highest occurrence of Globanomalina cf compressa & Subbotina trivialis.

▪ Increase in calcareous benthonic foram diversity = neritic Midway foraminiferal fauna.

~~Hiatus~~

DANIAN

Ekofisk Formation chalks and ’Intra-Danian Marls’.


Våle Formation / Ekofisk Formation Boundary

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Gradational boundary


Biozonation and Våle Formation.E-8, Våle Formation Reference Well

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Cored interval

Våle Fm

2057.6m: – superabundant

Cenosphaera sp.2 (clastic

preservation)

Actual Core Depth

(not depth shifted /

corrected)

Biostrat Core

Report Data

2057.75m:. – top chalky

preservation, abdt Plk

Forams.

2060.65m:– reapp. Common

Cenosphaera sp.2 & sp.1

Våle Formation

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Våle Formation

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Thinning by Base lap: onlap onto the high


Observations / thoughts: Våle Formation Change from Chalk (Ekofisk Fm) to the Våle Formation marls is gradational. The actual boundary may be

difficult to place. Upper part of Ekofisk is tight marly chalk: basinal.

However, some boundaries are sharp and there is an erosional (?) contact; highs and intr-basinal inversion highs (Valhall).

Våle Formation is in some areas absent and Lista Formation lies directly upon the Chalk Group – erosional contact in some areas with the Danian Ekofisk Fm completely removed.

Våle Fm comprise hemipelagic deposits and turbidite deposits. What is the degree of reworking? Erosion and redeposition of adjacent in-situ chalks – slump scars, winnowing on highs, talus slope deposits associated with escarpments.

The Underlying structural pattern / framework acts as a template controlling sea floor topography, sea floor currents and sedimentation patterns and erosion.

Localised salt movement affecting sedimentation depocentres and transport routes. Salt withdrawal –concentric fault pattern – (cauldron collapse) and conventional collapse structures.

Våle Fm = Kerteminde Marl = Lellinge Grnsnd onshore Denmark (Sjælland and Storebælt): distal to proximal.

Late Early Palaeocene (Mid Palaeocene) tectonic event accompanied by a global drop in sea level. Result: downwarping of the main basins centered above the Mesozoic rift system; intra-basin uplift complication; cessation of carbonate deposition; erosion of highs (reworking of chalks) and development of mass flow systems interbedded with hemipelagic sediments; influx of clastic material into basin; subsequent Sea level rise and submergence of highs by muds. Sea floor current erosion and channels / valleys.


Observations / thoughts: Våle formation

Mid Palaeocene erosion and incision of the Danian carbonate platform

Hemipelagic deposits plus mass-flow units

Common calcareous foraminifera – neritic ”Midway type” fauna, both benthonic and planktonic.

Open marine, (outer) neritic to upper bathyal.

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Note Revised Eocene boundary

Extent and timing of erosion?


Biozonation and Maureen Fm–Danish sector


Biozonation and the North Sea Marl Fm


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Selandian

Danian

Maastrichtian

Note the cycles of

abundance / frequency

Example Vertical Well,

Cuttings only

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Formation

Balder Formation

Sele Formation

Østerrende Clay

Lis

ta F

orm

atio

n

Holmehus Clay

Æbelø Clay”Grey Clay”

North Sea Marl Fm

Ekofisk Formation

Lista FormationAge: Late Paleocene

Lithology: Pale green-grey, red-brown and yellowish grey claystones

Upper boundary: The boundary between the Sele Fm and the

Lista Fm is often marked by a change from dark-grey/greenish

grey laminated mudstones to a multi-colored structureless mudstone.

Lower boundary: The boundary is characterized by a change from

multi-colored Holmehus claystone to dark green-grey Æbelø shale.

This boundary commonly corresponds to the base of a small GR-

peak.

Thickness: Where complete (e.g. Dan, Igor and Harald), the

thickness ranges from 40 to 70 ft. Holmehus Clay is missing on a few

structures (e.g. Valdemar).

Regional correlation: Corresponds to the entire Lista Formation

in the British North Sea stratigraphy.

Holmehus Clay

Æbelø Clay (Grey Clay)Lithology: Grey, silty, carbonaceous mudstone.

Upper boundary: See description of Holmehus Clay lower boundary.

Lower boundary: This boundary is marked by a downhole

decrease in GR-values and an increase in velocity associated with a

change from mudstone to marl or calcareous clay.

Thickness: The thickness is mostly around 20 ft. Æbelø Clay is

however missing on a number of structures (e.g. Tyra & Valdemar).

Regional correlation: Corresponds to the non-marly part of the

Maureen Fm in the British North Sea stratigraphy.

Hydrocarbons: In sand-bodies in the Norwegian-Danish Basin.


Onshore Denmark – Type area for Danian and Selandian stages.


UPPER CRETACEOUS- DANIAN FACIES MODEL


RESEDIMENTATION PROCESSES - Chalk


Comments (1)

Bryozoan debris in uppermost Danian of wells in the Danish Sector of the North Sea.

Indicative of winnowing on shoal / high areas?

Same processes as seen in quarries onshore Denmark?

No North Sea Marl / not recognized in some wells located in an erosional area. Normally the North Sea Marl is rich in radiolaria and calcareous foraminifera.

A good Danian section is indicated by insitu presence of the planktonic foraminifera G. pseudobulloides, G. triloculinoides and rare G. compressa. And G. daubjergensis if the sample interval is closely spaced.


Comments (2)

What was the Sedimentation rate in North Sea Marl times?

Wehat were the Water depths pre and post Selandian (Mid Palaeocene) unconformity?

What was the Initial sea floor topography and bathymetry?

Source of sediment? Eroded from within? Eroded from without? Plus pelagic material.

Palaeogegraphy of Mid Palaeocene times. Possibly a dynamic environment.

Pock marks. Water / gas escape?. Associated with fault lineations?


Comparative Lithostratigraphical Chart for the Palaeocene (from the Millennium Atlas)


north sea marl våle – maureen nomenclature linkedin version

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