Ice rafted debris of ODP Holes 104-642B and 104-644A in the Vøring Plateau
Studies of ice-rafted detritus in ODP holes from the Norwegian Sea document a series of glacial episodes in the surroundings of the Norwegian - Greenland Sea from the late Miocene (5.45 Ma) through the Pliocene. These glacial events were of smaller magnitude than those of the period postdating the m...
| Main Authors: | , , , |
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| Format: | Dataset |
| Language: | English |
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PANGAEA
2017
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| Subjects: | |
| Online Access: | https://doi.pangaea.de/10.1594/PANGAEA.882973 https://doi.org/10.1594/PANGAEA.882973 |
| Summary: | Studies of ice-rafted detritus in ODP holes from the Norwegian Sea document a series of glacial episodes in the surroundings of the Norwegian - Greenland Sea from the late Miocene (5.45 Ma) through the Pliocene. These glacial events were of smaller magnitude than those of the period postdating the major onset of large scale northern hemisphere glacial cyclicity at 2.57 Ma. A further amplification of the glaciations took place after 1.2 Ma. Oxygen isotope records from benthic foraminifers indicate high-frequency global ice volume fluctuations since the late Miocene. A major glacial episode took place at 5.1 – 5 Ma, which lowered eustatic sea-level by about 80 m below the present. Similar lowerings of sea-level are also documented for some glacials in the Pliocene (3.7 – 3.1 Ma). These glacials indicate substantially larger Antarctic ice volumes than at present. The glacial episode at 5 Ma is correlated with the upper evaporite sequence of the Messinian salinity crisis in the Mediterranean. The Norwegian Sea was a net exporter of deep-water during most of the last 6 Myr. Periods of carbonate dissolution lasting several 100 kyr indicate intervals of reduced ventilation and a more stable water column in the Norwegian Sea in both the late Miocene — Pliocene and the early Quaternary. There is no clear evidence for reduced deep-water formation during the upper Messinian event. High-frequency variation in δ 13C indicates that changes in deep-water ventilation rate were coupled with orbital forcing. While the ventilation and deep-water chemistry of the Norwegian Sea has varied during the late Neogene, the δ 18O results indicate that Norwegian Sea deep-waters were denser and colder than those of the Atlantic during major portions of the last 6 Myr. |
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