Neogene

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< Paleogene | N eogen | Quaternary >
23.03–2.588 million years ago
Atmospheric O 2 share
(average over period) 		approx. 21.5% by volume
(108% of today's level)
Atmospheric CO 2 share
(average over period) 		approx. 280 ppm
(approx. 70% current level)
Floor temperature (average over period) approx. 14 ° C
(0 ° C above today's level)
system series step ≈ age ( mya )
after that after that after that younger
Neogene Pliocene Piacenzium 2.588
⬍
3.6
Zancleum 3.6
⬍
5.333
Miocene Messinium 5.333
⬍
7,246
Tortonium 7,246
⬍
11.62
Serravallium 11.62
⬍
13.82
Langhium 13.82
⬍
15.97
Burdigalium 15.97
⬍
20.44
Aquitanium 20.44
⬍
23.03
before before before older

The Neogene (from Greek νέος néos "new" and -gen from γίγνομαι gígnomai "to become") is a section of the earth's history . According to today's definition, the geological age of the Cenozoic is divided geochronologically into three sections: the Paleogene , the Neogene and the Quaternary . In chronostratigraphy , the neogene is thus the second highest system . It corresponds to the outdated term Upper Tertiary or Young Tertiary .

The neogene is characterized by the development of birds and mammals . A land bridge was formed between the continents of North and South America and an exchange of fauna began. During the stage of the Messinian , the Mediterranean sea dried up . There was a slow climatic cooling up to the Ice Age of the Pleistocene .

Subdivision

Some fossils and reconstructions of the neogene fauna.
From Meyer's Konversations-Lexikon (1885–1890)

The Neogen is divided into two series :

climate

Desiccation of the Mediterranean Sea 5 million years ago

The Neogene brought a phase of intensified cooling up to the beginning of the first glaciations in the Gelasium , the lowest level of the Quaternary.

In the Miocene, at the beginning of the Neogene, the climate in the North Atlantic-Scandinavian region can still be described as moderate. This emerges from the study of the composition of the fossil marine fauna .

In the lower Pliocene there was an initial strong cooling phase in the area of ​​the poles, which was followed by a longer period of warming. A changing, but relatively rapid drop in temperature curves followed in the Pliocene.

At the end of the Pliocene, the polar ice caps were frozen. Ice masses were deposited on the continent of Antarctica and thereby withdrawn from the water cycle. This led to an initial drop in sea level.

The Pleistocene is known as the actual Ice Age , with alternating phases of glaciation in the northern parts of Eurasia and North America.

Concept history

Origin and change of the term

The term and the name Neogen go back to the Austrian geologist and paleontologist Moriz Hoernes , who used it as early as the mid-19th century to classify the deposits in the Vienna Basin . He divided the layers of the geological age of the Cenozoic into two periods, an older, the Paleogene, and a younger, the Neogene. The neogene also reached up to the uppermost layers, i.e. up to the present day.

The Neogene was later used to better describe the Tertiary , as its beginning 23.03 million years ago marks the cut between the Oligocene (belongs to the Old Tertiary) and the Miocene (belongs to the Young Tertiary) . However, the Neogene was reduced to the Miocene and Pliocene epochs and ended together with the Tertiary on the border with the Quaternary (1.8 million years ago).

A conflict arose between the International Stratigraphic Commission (ICS) and the International Union for Quaternary Research (INQUA) about the end point of the Neogene . The Quaternary geologists united in INQUA demanded in 2006 that the Neogene should not extend to the present day. Instead, it should end with the end of the Pliocene around 2.6 million years ago and the Quaternary system should begin with the beginning of the Gelasia . In June 2009 this proposal was ratified by the IUGS .

Change in the geological timescale in 2004

The terms tertiary and quaternary in the geological timescale were abolished in 2004 and replaced by paleogene and neogene. As early as 1978, a sub-commission of the International Commission for Stratigraphy (ICS) divided the Cenozoic into the two periods Paleogene and Neogene, as proposed by Hoernes 150 years ago. In 2004, the new Geologic Time Scale 2004 was presented as a result of the discussions of the past decades . In 2008 it should become internationally binding for all geologists. However, at the same time a redefinition and reintroduction of the Quaternary was promised.

Many Quaternary geologists were particularly critical of the deletion of the Quaternary, as the peculiarities of the Earth's development in the Ice Age, which differ significantly from the previous Pliocene, were not reflected in the new time scale. Their criticism has led to the Quaternary being re-included in the timescale and redefined. The period, which used to be 1.8 million years ago, has been extended to 2.6 million years and now includes all glacial sediments. This proposal was adopted in June 2009. Since then, the Quaternary begins with the Gelasium .

literature

  • Friedrich Strauch: On the climate of the North Atlantic-Scandinavian region in the younger Cenozoic. In: Journal of the German Society for Geosciences. Vol. 123, pp. 163-177, 1972

Individual evidence

  1. ↑ Oxygen content-1000mj
  2. ↑ Phanerozoic Carbon Dioxide
  3. ↑ All palaeotemps
  4. ↑ Moriz Hoernes: The fossil mollusks of the tertiary basin of Vienna , 1856 (Volume 1) and 1871 (Volume 2 completed by August Emanuel von Reuss .)
  5. ↑ Clague, John et al. (2006): Open Letter by INQUA Executive Committee . Quaternary Perspective, the INQUA Newsletter, International Union for Quaternary Research 16 (1). ( PDF ( Memento of January 7, 2010 in the Internet Archive ))

Web links

Commons : Neogen  - collection of images, videos and audio files