The Voort Formation or Voort Member ( nl, Formatie van Voort or ; abbreviation in

Belgium Belgium, ; french: Belgique ; german: Belgien officially the Kingdom of Belgium, is a country in Northwestern Europe. The country is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeast, France to th ...

: Vo or in the

Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherl ...

: VEVO) is a

stratigraphic Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy has three related subfields: lithostra ...

unit in the subsurface of north Belgium and the south of the Netherlands. The unit has the status of a

formation Formation may refer to: Linguistics * Back-formation, the process of creating a new lexeme by removing or affixes * Word formation, the creation of a new word by adding affixes Mathematics and science * Cave formation or speleothem, a secondar ...

in Belgium but is seen as a

member Member may refer to: * Military jury, referred to as "Members" in military jargon * Element (mathematics), an object that belongs to a mathematical set * In object-oriented programming, a member of a class ** Field (computer science), entries in ...

of the Veldhoven Formation in the Netherlands. The Voort Formation consists of

shallow marine Shallow water marine environment refers to the area between the shore and deeper water, such as a reef wall or a shelf break. This environment is characterized by oceanic, geological and biological conditions, as described below. The water in this ...

sands with a late Oligocene age ( Chattian

stage Stage or stages may refer to: Acting * Stage (theatre), a space for the performance of theatrical productions * Theatre, a branch of the performing arts, often referred to as "the stage" * ''The Stage'', a weekly British theatre newspaper * Sta ...

, about 25 million years old).

Stratigraphy

In Belgian

lithostratigraphy Lithostratigraphy is a sub-discipline of stratigraphy, the geological science associated with the study of strata or rock layers. Major focuses include geochronology, comparative geology, and petrology. In general, strata are primarily igneous ...

the Voort Formation is part of the

Rupel Group The Rupel Group is a stratigraphic group of rock strata in the subsurface of Belgium. It is subdivided into three formations that are all marine deposits (sands and clays) of Oligocene age. Name The Rupel Group was first named by Belgian geologis ...

, though other formations in this group are slightly older (of the early Oligocene

Rupelian The Rupelian is, in the geologic timescale, the older of two ages or the lower of two stages of the Oligocene Epoch/ Series. It spans the time between . It is preceded by the Priabonian Stage (part of the Eocene) and is followed by the Chattian ...

stage). In the Netherlands the Voort Member is part of the Veldhoven Formation. In Belgium, a

clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay par ...

ey subunit is treated as a member of the Voort Formation ( Veldhoven Member). In Dutch lithostratigraphy, this unit is classified as another member of the Veldhoven Formation and called the Wintelre Member. In Belgium the Voort Formation is stratigraphically below the early

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

marine

Berchem Formation Berchem () is a southern district of the municipality and city of Antwerp in the Flemish Region of Belgium. Berchem is located along the old ''Grote Steenweg'' (Dutch for 'Big Paved Road') that has connected Brussels to Antwerp for several centu ...

(in

province of Antwerp ) , native_name_lang = nl , settlement_type = Province of Belgium , image_flag = Flag of Antwerp.svg , flag_size = , image_shield = Wapen van de provincie Antwerpen.svg , shield_size ...

) or

Bolderberg Formation Heusden-Zolder (; li, Heuze-Zolder ) is a municipality located in the Belgian province of Limburg near Hasselt. On 1 January 2006 Heusden-Zolder had a total population of 30,769. The total area is 53.23 km² which gives a population densit ...

(in

Limburg Limburg or Limbourg may refer to: Regions * Limburg (Belgium), a province since 1839 in the Flanders region of Belgium * Limburg (Netherlands), a province since 1839 in the south of the Netherlands * Diocese of Limburg, Roman Catholic Diocese in ...

). In the Netherlands it is below the early Miocene Breda Formation. In Belgium the Voort Formation is on top of the older formations of the

( Boom Formation or Eigenbilzen Formation), in the Netherlands the Voort Member is on top of the Rupel Formation.

Lithology

The Voort Formation consists of a 60 meters thick layer of greyish to greenish micaceous and glauconiferous fine sand. This is alternated by greenish sandy clay. crags or

pyrite The mineral pyrite (), or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula Fe S2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral. Pyrite's metallic luster and pale brass-yellow hue giv ...

rich clay layers can occur locally. In the Roer Valley Graben the formation can be up to 300 meter in thickness.

References

*Laga, P.; Louwye, S. & Geets, S. (eds.); 2001: ''Paleogene and Neogene lithostratigraphic units (Belgium)'', Geologica Belgica 4(1-2), p. 135-152

External links

* ; 2003
Formatie van Veldhoven
TNO website ({{in lang, nl) Geologic formations of the Netherlands Geologic formations of Belgium Oligocene Series of Europe Paleogene Belgium Paleogene Netherlands