Bathymetric and isotopic evidence for a short-lived Late Ordovician glaciation in a greenhouse period
| Autor: | D. B. R. Robertson, Thomas F. Anderson, P. J. Brenchley, Linda Hints, Tõnu Meidla, D. G. F. Long, G. A. F. Carden, Jim D. Marshall |
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| Rok vydání: | 1994 |
| Předmět: | |
| Zdroj: | Geology. 22:295-298 |
| ISSN: | 1943-2682 0091-7613 |
| Popis: | The end Ordovician glaciation is distinct among Phanerozoic glaciations in that CO 2 , levels were generally high, yet major continental ice sheets accumulated on the Gondwana supercontinent. New oxygen isotopic data indicate substantial changes in sea-water temperatures and ice volume coinciding with glacio-eustatic changes in sea level reflecting the growth and decay of the Gondwana ice cap. Major glaciation was apparently confined to the Hirnantian and was 0.5-1 m.y. long, rather than the 35 m.y. of earlier estimates. Carbon isotope values indicate significant changes in carbon cycling as the oceans changed from a state with warm saline bottom waters to a state with cold deep-water circulation and then back again. We believe that the changes in the carbon cycle effected a reduction in P CO 2 levels in the oceans and atmosphere and thus promoted glaciation but were unable to sustain icehouse conditions in a greenhouse world. |
| Databáze: | OpenAIRE |
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