Landen Group
Encyclopedia
The Landen Group is a lithostratigraphic
unit (a "group
" of rock strata
) in the Belgian
subsurface
. The group consists of two formations of Thanetian
(late Paleocene
) to Ypresian
(early Eocene
) age. The Landen Group is named after the town of Landen
in Flemish Brabant
.
Both formations can be found in the subsurface of all northern Belgium. They crop out
in the province of Hainaut.
(marine marl
s, sands and clays of Selandian
to Thanetian age). In the Belgian lithostratigraphy, the Landen Group is overlain by the Ieper Group
, marine clays and sands of Ypresian age.
The Landen Group shares its name with the Landen Formation
in the lithostratigraphy of the Netherlands
. However, this Dutch formation contains not only the equivalents of the Belgian Landen Group but also strata that correlate
with the Belgian Opglabbeek Formation
and Heers Formation.
(eds.); 2001: Paleogene and Neogene lithostratigraphic units (Belgium), Geologica Belgica 4(1-2), p. 135-152.
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...
unit (a "group
Group (stratigraphy)
A group in stratigraphy is a lithostratigraphic unit, a part of the geologic record or rock column that consists of defined rock strata. Groups are divided into formations and are sometimes themselves grouped into "supergroups"....
" of rock strata
Stratum
In geology and related fields, a stratum is a layer of sedimentary rock or soil with internally consistent characteristics that distinguish it from other layers...
) in the Belgian
Belgium
Belgium , officially the Kingdom of Belgium, is a federal state in Western Europe. It is a founding member of the European Union and hosts the EU's headquarters, and those of several other major international organisations such as NATO.Belgium is also a member of, or affiliated to, many...
subsurface
Subsurface
Subsurface is the seventh studio album by British progressive metal band Threshold. The album was released in August 2004, and received an Album of the Month award in several European music magazines....
. The group consists of two formations of Thanetian
Thanetian
The Thanetian is, in the ICS' Geologic timescale, the latest age or uppermost stratigraphic stage of the Paleocene Epoch or series. It spans the time between and . The Thanetian is preceded by the Selandian age and followed by the Ypresian age...
(late Paleocene
Paleocene
The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...
) to Ypresian
Ypresian
In the geologic timescale the Ypresian is the oldest age or lowest stratigraphic stage of the Eocene. It spans the time between and , is preceded by the Thanetian age and is followed by the Eocene Lutetian age....
(early Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
) age. The Landen Group is named after the town of Landen
Landen
Landen is a municipality located in the Belgian province of Flemish Brabant. The municipality comprises the city of Landen proper and the towns of Attenhoven, Eliksem, Ezemaal, Laar, Neerlanden, Neerwinden, Overwinden, Rumsdorp, Waasmont, Walsbets, Walshoutem, Wange and Wezeren. On January 1, 2006...
in Flemish Brabant
Flemish Brabant
Flemish Brabant is a province of Flanders, one of the three regions of Belgium. It borders on the Belgian provinces of Antwerp, Limburg, Liège, Walloon Brabant, Hainaut and East Flanders. Flemish Brabant also completely surrounds the Brussels-Capital Region. Its capital is Leuven...
.
Subdivision
The Landen Group is subdivided into two formations:- The Hannut FormationHannut FormationThe Hannut Formation is a geologic formation in the subsurface of northern Belgium. The formation consists of marine clay and silt, alternating with moer sandy layers. On top of this the lithology changes to limestone, siltstone and sandstone and the top of the formation is formed by a layer of...
, an alternation of marineMarine (ocean)Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
clayClayClay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...
s, sandSandSand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...
s and limestoneLimestoneLimestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
s; - The Tienen FormationTienen FormationThe Tienen Formation is a geologic formation in the subsurface of northern Belgium. The formation crops out in the province of Hainaut and the Hesbaye region in the province of Limburg. It has a late Thanetian to early Ypresian age....
, a lagoonLagoonA lagoon is a body of shallow sea water or brackish water separated from the sea by some form of barrier. The EU's habitat directive defines lagoons as "expanses of shallow coastal salt water, of varying salinity or water volume, wholly or partially separated from the sea by sand banks or shingle,...
al-continentContinentA continent is one of several very large landmasses on Earth. They are generally identified by convention rather than any strict criteria, with seven regions commonly regarded as continents—they are : Asia, Africa, North America, South America, Antarctica, Europe, and Australia.Plate tectonics is...
al alternation of clay, sand and ligniteLigniteLignite, often referred to as brown coal, or Rosebud coal by Northern Pacific Railroad,is a soft brown fuel with characteristics that put it somewhere between coal and peat...
. This formation is known for its fossils.
Both formations can be found in the subsurface of all northern Belgium. They crop out
Outcrop
An outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth. -Features:Outcrops do not cover the majority of the Earth's land surface because in most places the bedrock or superficial deposits are covered by a mantle of soil and vegetation and cannot be...
in the province of Hainaut.
Stratigraphy
The Landen Group is stratigraphically on top of the Bertaimont Formation or Heers FormationHeers Formation
The Heers Formation is a geologic formation in the subsurface of Belgium. The formation consists of sand and marl and was deposited in the shallow sea that covered Belgium during the middle to late Selandian age of the Paleocene epoch....
(marine marl
Marl
Marl or marlstone is a calcium carbonate or lime-rich mud or mudstone which contains variable amounts of clays and aragonite. Marl was originally an old term loosely applied to a variety of materials, most of which occur as loose, earthy deposits consisting chiefly of an intimate mixture of clay...
s, sands and clays of Selandian
Selandian
The Selandian is in the geologic timescale an age or stage in the Paleocene. It spans the time between and . It is preceded by the Danian and followed by the Thanetian. Sometimes the Paleocene is subdivided in subepochs, in which the Selandian forms the "Middle Paleocene".-Stratigraphic...
to Thanetian age). In the Belgian lithostratigraphy, the Landen Group is overlain by the Ieper Group
Ieper Group
The Ieper Group is a group of rock strata in the subsurface of northwest Belgium. The group is subdivided into three marine formations, all formed during the Ypresian, a single age of the geologic timescale...
, marine clays and sands of Ypresian age.
The Landen Group shares its name with the Landen Formation
Landen Formation
The Landen Formation is a lithostratigraphic unit in the subsurface of the Netherlands. This formation shares its name with the Belgian Landen Group, but the Belgian unit is thinner and has different definitions...
in the lithostratigraphy of the Netherlands
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...
. However, this Dutch formation contains not only the equivalents of the Belgian Landen Group but also strata that correlate
Correlation
In statistics, dependence refers to any statistical relationship between two random variables or two sets of data. Correlation refers to any of a broad class of statistical relationships involving dependence....
with the Belgian Opglabbeek Formation
Opglabbeek Formation
The Opglabbeek Formation is a geologic formation in the subsurface of the eastern part of Belgian Limburg. The formation consists of lagoonal and fluvial clay and sand and was deposited during the early Selandian...
and Heers Formation.
(eds.); 2001: Paleogene and Neogene lithostratigraphic units (Belgium), Geologica Belgica 4(1-2), p. 135-152.