Rotliegend
Encyclopedia
The Rotliegend or Rotliegendes is a lithostratigraphic
unit (a sequence of rock strata) of Cisuralian (early Permian
) age that is found in the subsurface of large areas in western and central Europe
. The Rotliegend mainly consists of sandstone
layers. It is usually covered by the Zechstein
and lies on top of regionally different formations of late Carboniferous
age.
The name Rotliegend has in the past not only been used to address the rock strata themselves, but also the time span in which they were formed (in which case the Rotliegend was considered a series
or subsystem of the Permian). This time span corresponds roughly with the length of the Cisuralian epoch
.
, the last phases
of the Hercynian orogeny were still ongoing during the start of the Permian. At the same time local crustal extension
formed intramontane basins such as the large Permian Basin
which covered parts of present day Germany
, Poland
, Denmark
, the North Sea
, the Baltic Sea
and the Netherlands
. The early development of the basin went hand in hand with volcanism
. Apart from these volcanic deposits the basin was filled by the erosion
al products of the Hercynian mountains to the south: mostly sand
s and gravel
s deposited under an arid and warm climate.
: a Lower Rotliegend Group (mostly volcanic rocks: tuff
s and basalt
ic lava
s) and an Upper Rotliegend Group (sandstone
s and siltstone
s). During the formation of the lower group the basin was still small and the deposition was restricted to the centre of the basin in the southeastern North Sea and northern Germany, this group is very limited in thickness in the Dutch subsurface. The upper group has a larger arial distribution since the basin had grown wider.
In Dutch lithostratigraphy, the Rotliegend lies on top of the late Carboniferous Limburg Group and below the Zechstein Group. The Upper Rotliegend Group is divided in the Silverpit Formation and Slochteren Formation, the last is an important reservoir for hydrocarbon
s. The German Bentheim Sandstone, which crops out
in the Münsterland, is part of the Slochteren Formation.
The Rotliegend of northern Germany is continuous with that of the Netherlands. In other parts of Germany contemporaneous basins exist, such as the Saar-Nahe Basin, the Wetterau
or the Saale Basin. The Rotliegend of these different intramontane basins is not easy to correlate and the lithostratigraphy of each basin has its own divisions (groups and formations).
, ISBN 90-6644-125-9.
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 sequence of rock strata) of Cisuralian (early Permian
Permian
The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...
) age that is found in the subsurface of large areas in western and central Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
. The Rotliegend mainly consists of sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
layers. It is usually covered by the Zechstein
Zechstein
The Zechstein is a unit of sedimentary rock layers of Middle to Late Permian age located in the European Permian Basin which stretches from the east coast of England to northern Poland...
and lies on top of regionally different formations of late Carboniferous
Carboniferous
The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359.2 ± 2.5 Mya , to the beginning of the Permian Period, about 299.0 ± 0.8 Mya . The name is derived from the Latin word for coal, carbo. Carboniferous means "coal-bearing"...
age.
The name Rotliegend has in the past not only been used to address the rock strata themselves, but also the time span in which they were formed (in which case the Rotliegend was considered a series
Series (stratigraphy)
Series are subdivisions of rock layers made based on the age of the rock and corresponding to the dating system unit called an epoch, both being formally defined international conventions of the geological timescale. A series is therefore a sequence of rock depositions defining a...
or subsystem of the Permian). This time span corresponds roughly with the length of the Cisuralian epoch
Epoch (reference date)
In the fields of chronology and periodization, an epoch is an instance in time chosen as the origin of a particular era. The "epoch" then serves as a reference point from which time is measured...
.
Facies and formation
In large parts of PangaeaPangaea
Pangaea, Pangæa, or Pangea is hypothesized as a supercontinent that existed during the Paleozoic and Mesozoic eras about 250 million years ago, before the component continents were separated into their current configuration....
, the last phases
Tectonic phase
A tectonic phase or deformation phase is in structural geology and petrology a phase in which tectonic movement or metamorphism took place. Tectonic phases can be extensional or compressional in nature....
of the Hercynian orogeny were still ongoing during the start of the Permian. At the same time local crustal extension
Extensional tectonics
Extensional tectonics is concerned with the structures formed, and the tectonic processes associated with, the stretching of the crust or lithosphere.-Deformation styles:...
formed intramontane basins such as the large Permian Basin
Permian Basin (Europe)
The European Permian Basin is a thick sequence of sedimentary rocks deposited in a large sedimentary basin during the Permian period in North Europe. The basin underlies northern Poland, northern Germany, Denmark, The Netherlands and under a significant portion of the North Sea to Scotland...
which covered parts of present day Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
, Poland
Poland
Poland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...
, Denmark
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...
, the North Sea
North Sea
In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...
, the Baltic Sea
Baltic Sea
The Baltic Sea is a brackish mediterranean sea located in Northern Europe, from 53°N to 66°N latitude and from 20°E to 26°E longitude. It is bounded by the Scandinavian Peninsula, the mainland of Europe, and the Danish islands. It drains into the Kattegat by way of the Øresund, the Great Belt and...
and 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...
. The early development of the basin went hand in hand with volcanism
Volcanism
Volcanism is the phenomenon connected with volcanoes and volcanic activity. It includes all phenomena resulting from and causing magma within the crust or mantle of a planet to rise through the crust and form volcanic rocks on the surface....
. Apart from these volcanic deposits the basin was filled by the erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
al products of the Hercynian mountains to the south: mostly sand
Sand
Sand 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 gravel
Gravel
Gravel is composed of unconsolidated rock fragments that have a general particle size range and include size classes from granule- to boulder-sized fragments. Gravel can be sub-categorized into granule and cobble...
s deposited under an arid and warm climate.
Stratigraphy
In the north of Germany and in the Netherlands the Rotliegend is usually subdivided into two groupsGroup (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"....
: a Lower Rotliegend Group (mostly volcanic rocks: tuff
Tuff
Tuff is a type of rock consisting of consolidated volcanic ash ejected from vents during a volcanic eruption. Tuff is sometimes called tufa, particularly when used as construction material, although tufa also refers to a quite different rock. Rock that contains greater than 50% tuff is considered...
s and basalt
Basalt
Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...
ic lava
Lava
Lava refers both to molten rock expelled by a volcano during an eruption and the resulting rock after solidification and cooling. This molten rock is formed in the interior of some planets, including Earth, and some of their satellites. When first erupted from a volcanic vent, lava is a liquid at...
s) and an Upper Rotliegend Group (sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
s and siltstone
Siltstone
Siltstone is a sedimentary rock which has a grain size in the silt range, finer than sandstone and coarser than claystones.- Description :As its name implies, it is primarily composed of silt sized particles, defined as grains 1/16 - 1/256 mm or 4 to 8 on the Krumbein phi scale...
s). During the formation of the lower group the basin was still small and the deposition was restricted to the centre of the basin in the southeastern North Sea and northern Germany, this group is very limited in thickness in the Dutch subsurface. The upper group has a larger arial distribution since the basin had grown wider.
In Dutch lithostratigraphy, the Rotliegend lies on top of the late Carboniferous Limburg Group and below the Zechstein Group. The Upper Rotliegend Group is divided in the Silverpit Formation and Slochteren Formation, the last is an important reservoir for hydrocarbon
Hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons from which one hydrogen atom has been removed are functional groups, called hydrocarbyls....
s. The German Bentheim Sandstone, which crops 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 Münsterland, is part of the Slochteren Formation.
The Rotliegend of northern Germany is continuous with that of the Netherlands. In other parts of Germany contemporaneous basins exist, such as the Saar-Nahe Basin, the Wetterau
Wetterau
The Wetterau is a fertile undulating tract, watered by the Wetter, a tributary of the Nidda River, in the western German state of Hesse, between the hilly province Oberhessen and the north-western Taunus mountains....
or the Saale Basin. The Rotliegend of these different intramontane basins is not easy to correlate and the lithostratigraphy of each basin has its own divisions (groups and formations).
Literature
; 2004: A Geologic Time Scale 2004, Cambridge University Press; 1990 (2nd ed.): Geological Atlas of Western and Central Europe, Shell Internationale Petroleum Maatschappij BVRoyal Dutch Shell
Royal Dutch Shell plc , commonly known as Shell, is a global oil and gas company headquartered in The Hague, Netherlands and with its registered office in London, United Kingdom. It is the fifth-largest company in the world according to a composite measure by Forbes magazine and one of the six...
, ISBN 90-6644-125-9.