Environmental changes in the neogene and the biotic response |
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| Authors: | M S Barash |
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| Institution: | 1.Shirshov Institute of Oceanology,Russian Academy of Sciences (IO RAN),Moscow,Russia |
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| Abstract: | Among the abiotic factors that determined via the paleoceanographic processes development and evolution of the oceanic biota
in the Neogene, noteworthy are the tectonic, volcanic, climatic and extraterrestrial events. The most important tectonic events
of such kind include the subsidence of the Faroe-Iceland Threshold 14–13 Ma ago, the closure of the Tethys Ocean in the east
19–12 Ma ago, the orogenesis in the western Mediterranean region and closure of the Mediterranean Sea (Messinian Crisis) 5.59–5.33
Ma ago, the formation of the Central American Isthmus 6.0–3.5 Ma ago, and the opening of the Bering Strait that occurred (according
to different data) in the period of 7.4 to 3.1 Ma ago. The most significant climatic consequence resulted from the formation
of the Circum-Antarctic Current, the irregular growth of the Antarctic ice shield, the cooling in the Arctic region 3.2–3.1
Ma ago, and the development of continental glaciations in the Northern Hemisphere approximately 2.5 Ma ago. The variations
in the atmospheric CO2 content are correlative with the climatic fluctuations. The entire Cenozoic climatic record reflects the influence of the
orbital parameters of the Earth. The Neogene was marked by several significant extraterrestrial events: the fireball falling
in southwestern Germany in the middle Miocene 14.8–14.5 Ma ago probably accompanied by enhanced volcanic activity particularly
in the rift valley of eastern Africa; the drastically increased influx of interplanetary dust due to the disruption caused
by a large asteroid in the late Miocene 8.3 ± 0.5 Ma ago, the fall of a large (>1 km in diameter) asteroid in the Eltanin
Fault zone of the Southern Ocean in the terminal Pliocene 2.15 Ma ago; and the explosion of a supernova star, which was probably
responsible for the partial extinction of marine organisms at the Pliocene-Pleistocene transition approximately 2 Ma ago. |
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