Paratethys

The Paratethys is in the earth's history a marginal sea of Eurasia, predominantly formed on continental crust between the auffaltenden alpidischen mountains and the Eurasian mainland. It stretched in the Paleogene and Neogene from the Rhône region, up to the region of today's Aral Sea.

Geographical breakdown

The Paratethys today by facies, biogeographical and plate tectonic aspects divided into a western Paratethys, which includes the Rhone and Molasse Basin by Switzerland to the west Bavaria. The central Paratethys extends from Bavaria to the eastern foredeep of the Carpathian Mountains, including the inner-alpine basin, of the Vienna Basin, the Styrian Basin and the Pannonian Basin. The eastern Paratethys extends over the vast areas of the euxinic basin to the Black Sea to the Aral Sea in the east.

The remains of the Paratethys are the Black Sea, the Caspian Sea and Lake Ohrid, on the border between Macedonia and Albania. In the area of today's Lake Neusiedl and Balaton, a brackish -water lake was formed in the upper Miocene of the Pannonian Lake. However, both lakes is not existing for a long time such as lakes Lake Ohrid and therefore no direct successor waters of the Paratethys.

Naming and history

The term Paratethys was in 1924 by Vladimir Dmitrievich Laskarew ( 1868-1954 ) proposed primarily to delineate the faunas of the Paratethys from the Mediterranean faunas.

Plate tectonic situation

Due to the drift of North Africa, together with the still firmly connected to the Arabian Peninsula and the present-day Indian plate of the Tethys Ocean disappeared from the Upper Eocene increasingly in the forming alpidischen orogens. To the west of the southern Tethysarm was gradually reduced to a small residue which today is in the eastern Mediterranean. The northern Tethysarm north was reduced to a narrow, deep basin basically the alpidischen collision front. South of India was formed a new ocean, the Indian Ocean. In the course of alpidischen orogeny of Orogenfront formed approximately at the Eocene / Oligocene boundary north a predominantly continental marginal sea, the Paratethys, and in the western part of the orogen, south of its front, the Mediterranean Sea. In other tectonic sequence of events also formed in the western Mediterranean new oceanic sub-basins. The deposition area of the western part of the Paratethys is also commonly called Molasse Basin.

Paleogeography and sedimentation

At the Eocene / Oligocene boundary, the western Paratethys was largely cut off from the Mediterranean. Only in the western foothills and in the area of ​​present-day Slovenia were opened even deeper marine areas to the Mediterranean. The Danish -Polish road and another strait in the area of the Rhine Graben joined the Paratethys during NP21 ( Paläogennannoplankton zone 21 = lower regional Northern German stage Latdorfium, lower global stage Rupelium ) with the North Sea. A first level of isolation of the Paratethys indicated with the sedimentation of black shales in the subsequent zone NP 22. In the upper part of NP 22, the widespread Spiratella/Limacina- or pteropod marls came to deposit that can be used as a marker horizon for correlation quasi. In the Eastern Paratethys sedimentation did not keep pace with the lowering. In the ever-widening pool formed under conditions of hydrogen sulfide black shales and manganese ores. These deposition conditions stopped in the eastern part of the entire Oligocene and Lower Miocene. In the zone NP23, the compounds were added to the oceans largely interrupted, and it came under anaerobic conditions for the deposition of dark, banded clays, nannoplankton - marls, which contain only one type, and limnic - brackish diatomite. Marine faunas are known only from the western part of the Paratethys.

It was only in the mid- Oligocene ( NP24 = regional stage of Kiscelliums global stage of Aquitaniums ) fully marine conditions presented themselves throughout the Paratethys area again. The sea road in the area of present-day Slovenia was wider. Presumably there was also a connection from the Indian Ocean to the Paratethys in the area of present-day Caucasus. It now predominantly clastic sediments ( clay and sand stones) were deposited, some as turbidites. At the end of the Oligocene, the sea from the western part of the Paratethys pulled back to the line from Munich to Salzburg, so that only lacustrine and fluvial sediments were deposited ( "Lower Freshwater Molasse "). Further east widened the connections to the open sea. In the area of Thrace also a new connection opened during the Zone NP25 to the Mediterranean. These relationships held down to the bottom of Miocene ( NN1 = Neogennannoplankton zone 1 ). Marine faunas from the area of ​​present-day Iran ( molluscs and large Foraminifera ) were able to penetrate into the central regions of the Paratethys. In Burdigalium were close faunal relationships for the Indo-Pacific region. A horizon with huge pectinids shells and other large breed molluscs stretched from California to the Bavarian Molasse Basin.

In the lower Burdigalian ( = Eggenburgium ) opened the connection in the Western Paratethys again, for the marine connection closed in the territory of Slovenia. In the upper Burdigalian ( Ottnangium ) Africa collided with the still affiliated Arabian Peninsula with the Anatolian plate, and the connection to the Indian Ocean was interrupted. The Mediterranean was now exclusively a bay of the Atlantic Ocean. The eastern Paratethys lost its connection to the open sea and sweetened from the so-called Kotsakhurium Basin originated in the developed an endemic fauna. In the western Tethys connection to the Mediterranean remained open, a narrow corridor opened across the Rhine Graben to the North Sea. The eastern part of Carpathian foredeep was a Evaporitbecken. At the end of Ottnangium occurred regression and estuarine sediments were deposited in the central Paratethys.

In the middle Miocene, there was a transgression that can be correlated with the base of Langhium. Between Anatolia and the Arabian peninsula, a new connection between the Mediterranean and the Indian Ocean, a marine connection in eastern Anatolia between the Eastern Paratethys and the Indian Ocean opened, as well. However, this marine compound did probably not fully marine conditions for the entire basin. This sea-level high stand was also coupled with tropical conditions in Paratethysbereich, which extended to the south of Poland.

The regression in the lower Serravallium finished the connections of the Paratethys to the open sea largely. The eastern Paratethys became the Karaganium Lake. In the central Paratethys the Transylvanian Basin and the Carpathian foredeep became Evaporitbecken. Only the Pannonian basin maintained a connection to the Mediterranean Sea. This compound joined during the Serravallium. But again opened a marine connection to the eastern and central Paratethys, as Indo-Pacific faunas show in the Paratethys. The last time marine conditions from the Vienna Basin in the west to put one to the Trans- Caspian Basin in the east.

At the end of the Badenian Paratethys was largely isolated from the open sea. Probably only existed a narrow marine connection between the Mediterranean and Eastern Paratethys over eastern Anatolia.

At the beginning of Sarmatiums probably lost even this marine connection. The salinity decreased and - more important for the faunal - the alkalinity increased. All stenohalinen organisms died out. The fauna resembled on the whole (residual) field of Paratethys. In the area of the central Paratethys, the sedimentation increasingly reduced, and the Karpatenvortiefe fell dry. In the Carpathian arch, a brackish lake formed with greatly reduced salinity, the Pannon Sea. In this area the Sarmatian faunal died out almost completely, while the Sarmatfauna in the Dacian and euxinic subbasin further ausdauerte. There, a proliferation of bivalve molluscs of the family of Mactridae occurred in Bessarabium and Khersonium. In the upper Khersonium there was a regression that briefly isolated the Black Sea, but which was flooded again in the lower Maeotium. A further regression in the upper Maeotium led to the almost freshwater conditions of Pontium. The Pontic sea stretched from the Pannonian Basin to the Black Sea. With the Pliocene transgression the present conditions is presented about a.

Stratigraphy

Kon. = Konkium, Kar = Karaganium, Tsh. = Tshokrakium, Sar. = Sarmatian, Kh = Khersonium, Bess. = Bessarabium, Volh. = Volhynium

In the central and eastern Paratethysbereich deviates from the global stratigraphy steps outline is used as the local sedimentary rocks are often very difficult to correlate with the global structure. In the western area following structure is used:

  • Romanium
  • Dacium
  • Pontium
  • Pannonium
  • Sarmatian
  • Badenian
  • Karpatium
  • Ottnangium
  • Eggenburgium
  • Egerium
  • Kiscellium

In the Eastern Paratethys area, approximately in the region of the Black Sea and the Caspian Sea, other regional levels are mostly used.

  • Kimmerium
  • Pontium
  • Maeotium
  • " Sarmatian " ( not identical with the Sarmatian of the Western Paratethys ), usually divided from bottom to top in: Volhynium, Bessarabium and Khersonium
  • Konkium
  • Karaganium / Tshokrakium ( are usually grouped together )
  • Tarkhanium
  • Kotsakhurium
  • Sakaraulium
  • Karadzhalganium
  • Kalmykium
  • Solenovium
  • Pshekium
History of the Earth Lake Balaton Mediterranean Basin Continental shelf Tectonics Horizon (geology) Curb Brackish water Aquitanian (stage) Caucasus Mountains Sandstone Pectinoida Evaporite Marine regression Langhian Serravallian Subcarpathia Tortonian Messinian Gelasian Mya (unit) Proto-Tethys Ocean Digital Object Identifier
633435
de