The Buntsandstein or Bunter sandstone is a lithostratigraphic

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...

 and allostratigraphic unit (a sequence of rock strata) in the 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....

 of large parts of west and central Europe. The Buntsandstein predominantly 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 of the Lower Triassic 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...

 and is one of three characteristic Triassic units (together with the Muschelkalk

Muschelkalk

The Muschelkalk is a sequence of sedimentary rock strata in the geology of central and western Europe. It has a Middle Triassic age and forms the middle part of the Germanic Trias, that further consists of the Buntsandstein and Keuper...

 and Keuper

Keuper

The Keuper is a lithostratigraphic unit in the subsurface of large parts of west and central Europe. The Keuper consists of dolostone, shales or claystones and evaporites that were deposited during the Middle and Late Triassic epochs...

 that form the Germanic Trias

Germanic Trias

The Germanic Trias Supergroup is a lithostratigraphic unit in the subsurface of large parts of western and central Europe and the North Sea...

 Supergroup.

The Buntsandstein is similar in age, facies and lithology

Lithology

The lithology of a rock unit is a description of its physical characteristics visible at outcrop, in hand or core samples or with low magnification microscopy, such as colour, texture, grain size, or composition. It may be either a detailed description of these characteristics or be a summary of...

 with the Bunter

Bunter (geology)

Bunter beds are sandstone deposits containing rounded pebbles, such as can notably be found in Warwickshire, Cheshire, Staffordshire, Nottinghamshire, Yorkshire, Devon and Dorset in England...

 of the British Isles

British Isles

The British Isles are a group of islands off the northwest coast of continental Europe that include the islands of Great Britain and Ireland and over six thousand smaller isles. There are two sovereign states located on the islands: the United Kingdom of Great Britain and Northern Ireland and...

. It is normally lying on top of the 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...

 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 below the Muschelkalk. In the past the name Buntsandstein was in Europe also used in a chronostratigraphic

Chronostratigraphy

Chronostratigraphy is the branch of stratigraphy that studies the age of rock strata in relation to time.The ultimate aim of chronostratigraphy is to arrange the sequence of deposition and the time of deposition of all rocks within a geological region, and eventually, the entire geologic record of...

 sense, as a subdivision of the Triassic system. Among reasons to abandon this use was the discovery that its base lies actually in the latest Permian.

Origin

The Buntsandstein was deposited in the Germanic Basin, a large sedimentary basin

Basin (geology)

A structural basin is a large-scale structural formation of rock strata formed by tectonic warping of previously flat lying strata. Structural basins are geological depressions, and are the inverse of domes. Some elongated structural basins are also known as synclines...

 that was the successor of the smaller 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...

 and spread across present day 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...

, Germany, 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 southern regions of 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...

 and 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...

, 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...

 and south England. In the late Permian this region had an arid climate and it was covered by inland seas which deposited the Zechstein evaporite

Evaporite

Evaporite is a name for a water-soluble mineral sediment that result from concentration and crystallization by evaporation from an aqueous solution. There are two types of evaporate deposits, marine which can also be described as ocean deposits, and non-marine which are found in standing bodies of...

s. At the end of the Permian a connection with the Paleo-Tethys Ocean

Paleo-Tethys Ocean

The Paleo-Tethys Ocean was an ancient Paleozoic ocean. It was located between the paleocontinent Gondwana and the so called Hunic terranes. These are divided into the European Hunic and Asiatic Hunic...

 to the south was formed in present day southeast Poland, causing sea water to flow in periodically. This caused the inflow of more clastic material, which was deposited in the form of large alluvial fan

Alluvial fan

An alluvial fan is a fan-shaped deposit formed where a fast flowing stream flattens, slows, and spreads typically at the exit of a canyon onto a flatter plain. A convergence of neighboring alluvial fans into a single apron of deposits against a slope is called a bajada, or compound alluvial...

s.

Deposition took place in an arid, continental

Continental

Continental is the adjective form of continent.Continental may also refer to:* Continental , an album by UK band Saint Etienne* Continental , a brand of dried and pre-packaged foods used by Unilever in Australia...

 environment (playa

Dry lake

Dry lakes are ephemeral lakebeds, or a remnant of an endorheic lake. Such flats consist of fine-grained sediments infused with alkali salts. Dry lakes are also referred to as alkali flats, sabkhas, playas or mud flats...

 facies), so that there was little chemical weathering. Therefore the Bundsandstein deposits are typical red beds

Red beds

Red beds are sedimentary rocks, which typically consist of sandstone, siltstone, and shale that are predominantly red in color due to the presence of ferric oxides. Frequently, these red-colored sedimentary strata locally contain thin beds of conglomerate, marl, limestone, or some combination of...

, mainly sandstones and conglomerates

Conglomerate (geology)

A conglomerate is a rock consisting of individual clasts within a finer-grained matrix that have become cemented together. Conglomerates are sedimentary rocks consisting of rounded fragments and are thus differentiated from breccias, which consist of angular clasts...

 with little clay

Clay

Clay 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...

.

The late Anisian

Anisian

In the geologic timescale, the Anisian is the lower stage or earliest age of the Middle Triassic series or epoch and lasted from 245 million years ago until 237 million years ago, approximately...

 saw a major rise of the global (eustatic) sea level. A tropical sea filled the Germanic Basin then, stopping the deposition of the Bantsandstein and marking the beginning of the deposition of the Muschelkalk.

Stratigraphy

The Buntsandstein belongs to the Changhsingian

Changhsingian

In the geologic timescale, the Changhsingian or Changxingian is the latest age or uppermost stage of the Permian. It is also the upper or latest of two subdivisions of the Lopingian epoch or series. The Changhsingian lasted from 253.8 ± 0.7 to 251.0 ± 0.7 million years ago...

 to Anisian stages, meaning it is between 252 and 246 million years old.
In German lithostratigraphy, it is seen as a group, in the Netherlands and North Sea the name has no official status (though that does not keep geologists from using it). In the official Dutch lithostratigraphy, the Buntsandstein is divided into the Lower and Upper Germanic Trias Groups. The British Bunter Formation is basically a continuation of the same unit.

In Germany the Buntsandstein is subdivided into three subgroups with seven formations (from top to base):

Upper Buntsandstein

• Röt Formation or Fährtensandstein

Middle Buntsandstein

• Solling Formation
• Hardegsen Formation
• Detfurth Formation
• Volpriehausen Formation

Lower Buntsandstein

• Bernburg Formation
• Calvörde Formation

All of these are reasonably good reservoir rocks for oil and gas. In the Dutch subdivision, the upper two formations are part of the Upper Germanic Trias and the others part of the Lower Germanic Trias.

Fossils

The Buntsandstein contains a few small saurians, tracks like Chirotherium

Chirotherium

Chirotherium, also known as Cheirotherium , is the name of a Triassic archosaur known only from fossil imprints of its tracks...

 and plant remnants.

Literature

; 2004: A Geologic Time Scale 2004, Cambridge University Press.; 1990: Geological Atlas of Western and Central Europe, Shell Internationale Petroleum Maatschappij BV

Royal 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...

(2nd ed.), ISBN 90-6644-125-9.

External links

• (In Dutch) Structural description of the Dutch Triassic, including stratigraphic diagrams, website of TNO.