Carboniferous

The carbon in the Earth's history, the fifth chronostratigraphic system or the fifth geochronological period of the Paleozoic. The carbon began about 358.9 million years ago and ended about 298.9 million years. It is overlaid by Permian and underlain by the Devonian.

• 8.1 Carboniferous limestone facies
• 8.2 Kulm facies
• 8.3 The Variscan orogeny
• 8.4 Upper Carboniferous - The postvariszische development
• 8.5 Subvariszikum

History and naming

The carbon was introduced in 1822 by William Daniel Conybeare and William Phillips in England as a geological system ( = period) ( Carboniferous Series). The name derives from the world's most widespread coal seams are (Latin carbo, coal ' ), especially in the Upper Carboniferous. In German literature is sometimes also called " (rock ) Coal Age" in use.

Definition and GSSP

The lower limit of the Carboniferous ( Mississippian and at the same time the series and the Tournaisian stage) is defined by the first appearance of the conodont species Siphonodella sulcata within the line of development of Siphonodella praesulcata to Siphonodella sulcata. The upper limit and thus the lower limit of the Permian is the first appearance of the conodont species Streptognathodus isolatus. The official reference profile of the International Commission on Stratigraphy (Global Stratotype Section and Point, GSSP ) for the Carboniferous is the La Serre profile in the southeastern Montagne Noire ( France). It is an approximately 80 cm deep blight on the southern slope of the mountain La Serre, about 125 meters south of the summit (252 m ), approximately 525 m east of the Maison La Roquette, 2.5 km northeast of the town Fontès ( Hérault, cabrières, France).

Subdivisions of the Carboniferous

The Carboniferous is divided into two subsystems internationally and six series with a total of seven stages.

• System: Carboniferous ( 358.9 to 298.9 mya ) Subsystem: Pennsylvanian (formerly Upper Carboniferous ) ( 323.2 to 298.9 mya ) Series: Oberpennsylvanium ( 307 to 298.9 mya ) Level: Gzhelium ( 303.7 to 298.9 mya )
• Level: Kasimovian ( 307 to 303.7 mya )

• Level: Moscovian ( 315.2 to 307 mya )

• Level: Bashkirian ( 323.2 to 315.2 mya )

• Series: Obermississippium ( 330.9 to 323.2 mya ) Level: Serpukhovian ( 330.9 to 323.2 mya )

• Level: Viseum ( 346.7 to 330.9 mya )

• Level: Tournaisium ( 358.9 to 346.7 mya )

Regional were further subdivisions in use. The Central European carbon was divided into Dinantium ( Lower Carboniferous ) and Silesium ( Upper Carboniferous ). The border between the Central European Lower and Upper Carboniferous and international under-and Upper Carboniferous however, differs. The upper limit of the Silesium does not match with the international carbon - Permian boundary but remains well in the international division Gzhelium level. The Russian Carboniferous was divided into Upper, Middle and Lower Carboniferous.

The biostratigraphic zonation is based primarily on marine invertebrates: goniatites (a group of ammonites), conodonts ( tooth-like hard parts skull loose chordates ), brachiopods ( Brachiopoda ), corals and large Foraminifera. In the Upper Carboniferous biostratigraphic subdivision of the terrestrial ( continental ) deposits is based in part on land plants.

Paleogeography

As early as the Silurian it had come to the collision of the two continental masses Laurentia (North America) and Baltica ( Northern Europe and Russian panel). This plate tectonic event is called the Caledonian orogeny. The newly formed continent bears the name Laurussia or Old- Red- continent. Between Laurussia and the more southerly super continent of Gondwana (Africa, South America, Antarctica, Australia and India ) was a by various terranes, smaller masses of continental crust, structured maritime space. First collisions in this area had been initiated by the Variscan orogeny already in the lower Devonian. During the Carboniferous, the convergence of Laurussia and Gondwana continued and reached at the turn of the Lower and Upper Carboniferous a first climax. This continent / continent collision is the cause of the Variscan orogeny in Europe. In the Upper Carboniferous, the area between Northwest Africa and North America concluded the formation of the Appalachians was thus their conclusion. With the connection of the Siberian and Kazakhstan craton to Laurussia (applies to the Ural Mountains arose ) were finally in the Permian all the great continent masses into a supercontinent, Pangaea, united. The surrounding Pangaea is called Panthalassa Ocean.

Climate

At the beginning of the Carboniferous, the southern tip of Africa was in the area of the South Pole. Later in the Carboniferous Gondwana itself turned clockwise, at the beginning of the Permian to Antarctica was over the South Pole. In the Lower Carboniferous already formed first glaciations, but the ice propagation was only at the border Carboniferous / Permian its peak. Permo - Carboniferous evidence of this glaciation can be found on all parts of the Gondwana continent in the form of tillites ( moraine ) in several sedimentary horizons. This suggests a multiple exchange of warm and cold periods. One reason for the widespread coal deposits of the Upper Carboniferous can be seen in glacio - eustatic sea-level changes that have been caused by repeated formation of large Inlandseismassen in the south area of Gondwana. Near the equator, subtropical conditions influenced the carbon landscape. The oxygen content of the air was very high and was approximately 35%. This enabled a huge growth in insects and other arthropods. Landscape reconstructions of the carbon are often presented in museums in the form of graphs. A complete walk- carbon landscape can be viewed Landsweiler speeches in Saarland on the site of the former pit.

Development of the fauna

At the end of the Devonian, there was a mass extinction in which 50 % of all species became extinct, including some fish, corals and trilobites. It also died several reef builders among the corals. This meant that the number of coral reefs decreased. Some scholars are of the opinion that thereby the oxygen content fell in the water. This could have provided an impetus for the development line of amphibians. It was only in the mid- Carboniferous came again to a larger radiation. The fossils poor time from 360 million to 345 million years ago is called after the paleontologist Alfred Romer as " Romer - gap " (English Romer - Gap ).

Life in the oceans

The placoderms, which were the dominant group in the oceans of Devon, did not recover from mass extinction at the turn of Devon / carbon. The trend was towards more flexible forms of ray-finned fishes. The trilobites were important index fossils since the Cambrian, survived with only a few species in the Carboniferous and lost their previous significance.

Other rock-forming organisms were bryozoans ( Bryozoa, pinnate or fan-shaped, colony-forming animals) and forms of foraminifera, the large Foraminifera (especially Schwagerina and Fusulina from the order of Fusulinida ). Large Foraminifera are single-celled, benthic living, amoeboid creatures, but reaching up to 13 cm in size.

The ammonoids, a group of cephalopods ( Cephalopoda ), developed a great diversity in the Carboniferous. The biostratigraphy of the Carboniferous is largely based on this group. The first inside -shelled cephalopods ( squid or Coleoidea ) appear.

Living in the country

The oldest, wingless insects ( Insecta ) are already known from the Lower Devonian. The oldest winged insects date from the Upper Devonian. In the Upper Carboniferous winged insects were already developed very diverse. Due to the high oxygen content of the atmosphere formed during the Carboniferous among insects giant forms, so the dragonfly Meganeura. The formerly been regarded as the largest known spider genus Megarachne is today counted among the Eurypteriden.

The only terrestrial vertebrates of the Carboniferous were basal tetrapods, ie especially amphibians and the first reptiles, including the Protorothyrididae. However, many forms, such as Crassigyrinus retained an aquatic or at least semi- aquatic lifestyle. The amphibians were on land no food competitors and developed diverse forms. Some species reached sizes of up to six meters.

The first reptiles associated skeletons have been found at the base of the Upper Carboniferous. Probably developed during the Upper Carboniferous also known as the amniotic egg, with a fixed outer shell and two yolk sacs. Since the amniotic egg is an enclosed body of liquid in it, it meant greater independence from the water in reproduction.

Development of Flora

It is the Carboniferous, at least the Upper Carboniferous, also designated as the age of ferns. In far-flung coal swamps developed the world's largest reserves of coal. The dominant representatives of the flora in the coal swamps were the genera shed trees ( Lepidodendron ) and seal trees ( Sigillaria ), tree-like plants ( Lycopodiopsida ) are counted for the class of Bärlapppflanzen. The representatives of both genera reached sizes of up to 40 meters and trunk diameter of over one meter.

The horsetails ( Equisetopsida ) brought the Calamites ( Calamites ) also up to 20 meters wide tree shapes out ( most are from the tribes only casts the lignified medullary tubes preserved).

The published already in the Devonian group of vascular spore plants ( Pteridophyta ) brought with Glossopteris ( on the southern continent of Gondwana at that time ) also tree-like shapes out. These plants showed growth rings due to the Gondwana glaciation in the Upper Carboniferous.

Since the Upper Carboniferous, the first representatives of the Nacktsamigen plants ( gymnosperms, gymnosperms ) can be detected. Known examples of Carboniferous seed plants are the seed ferns and the needle bearing Cordaiten. The to the Voltziales scoring, also needled species Lebachia the Utrechtiaceae and Walchia occur only in the uppermost Upper Carboniferous. About the systematic classification of the two genera are different opinions, some, for example, the genus name Lebachia is replaced by Utrechtia, Walchia is often done as a form genus for not sure einordbare fossils ( conifers known in English as walchian ). Also the Cordaite first appear towards the end of the Carboniferous. These forests forming conifers did not survive the mass extinction in the Permian. The Cordaiten and the extinct in the lower Jurassic Voltziales will be provided to conifers (pine trees ).

The carbon in Central Europe

Carboniferous limestone facies

( Had the continent in the Silurian by the collision of Laurentia (North America) and Baltica ( Northern Europe and Russia) formed ) on the southern edge of Laurussia occurred in the Lower Carboniferous sedimentation of very fossiliferous limestones. The area of ​​the so-called Carboniferous limestone facies stretched from Ireland / England, Belgium and the Ardennes on the left bank of the Rhine Slate Mountains to Poland. In the area of England, the marine Karbonatsedimentation was organized by several high zones (especially the London - Brabant Massif and the Norman threshold). To deposit came bryozoans - reef limestones, Schuttkalke and dark bituminous limestones. At fossils mainly bryozoans, corals, brachiopods ( Brachiopoda ), goniatites and crinoids are preserved. The thickness of the Carboniferous reached 300 to 700 meters and is the south in the Kulm facies, see below, interlocked by Riffschutt and Kalkturbidite.

Kulm facies

The Kulm facies closes south of the Carboniferous limestone facies on, it represents a synorogene sedimentation, ie deposits, which occurred simultaneously with the Variscan orogeny of the orogeny. The clastic material were then supplied by the Central German Crystalline threshold, then an island arc. The sedimentation basin, where the Kulm facies came to the deposition, was divided by this threshold roughly divided into a northern and a southern area. The northern area now forms the Rhenish Slate Mountains. In this pelvic area came primarily shale ( with the shell bivalves Posidonia becheri ) and radiolarian chert leading ( lydite ) for deposit.

In the southern part prevailed a Flyschfazies with turbiditic sandstones, greywacke and Olisthostromen. The Kulm facies reached thicknesses of up to 3,000 meters in the southern basin.

The Variscan orogeny

In the Variscan Mountains is a complex built ceiling and fold mountains. The enormous crustal shortening is manifested in strong Verfaltungen and internal thrusts. The name comes from the Variskern, a resident of the Vogtland tribe. The Central European Variszikum is divided from north to south in the following zones:

• The Subvariszikum represents a Molassetrog, who received the ablation products of the rising mountains in the Upper Carboniferous. In Subvariszikum, or at its edge area also developed in the Upper Carboniferous the largest mass of the central European coal deposits.
• The Rhenoherzynikum includes resin, Ardennes, Rhenish Slate Mountains and extends to Cornwall.
• For Saxothuringian include the Sudetes, the Erzgebirge, Thuringian and Franconian Forest, Spessart and Odenwald and the northern areas of the Vosges and the Black Forest, where Odenwald, Spessart and also Palatinate, Ruhla and Kyffhaeuser belong to the Central German Crystalline Zone, which is the northern part of Saxothuringian.
• The Moldanubicum includes the Bohemian Massif, the Black Forest and the Vosges.

The first collisions of terranes ( smaller masses of continental crust ) have already taken place in Devon. Skip to main folding phase of the Variscan orogeny occurred at the border upper / lower Carboniferous, also referred to as sudetische phase. Until the Perm is in the Central European Variscan tectonic activity detectable.

Upper Carboniferous - The postvariszische development

During the main phase of the Variscan orogeny large parts of Europe had become mainland and thus ablation areas. The sedimentation in the Upper Carboniferous differed so fundamentally from the conditions in the Lower Carboniferous.

Subvariszikum

So that new wetlands by repeated rise and fall of sea marshes are flooded, covered by mud and back to the mainland: a belt with extensive paralic coal swamps ( paralischer to the emergence of coals developed at the edges of Subvariszischen basin mainly in Westfalium it comes to coastal areas develop ). This belt paralischer coal swamps withdrew from southern England over the Ruhr area to Poland. In the Ruhr the Upper Carboniferous reaches a maximum thickness of 6000 meters.