Isotopic Evidence for Glaciation During the Cretaceous Supergreenhouse
The Turonian (93.5 to 89.3 million years ago) was one of the warmest periods of the Phanerozoic eon, with tropical sea surface temperatures over 35°C. High-amplitude sea-level changes and positive δ 18 O excursions in marine limestones suggest that glaciation events may have punctuated this episode...
| Published in: | Science |
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| Main Authors: | , , , , , , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
American Association for the Advancement of Science (AAAS)
2008
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1126/science.1148777 https://www.science.org/doi/pdf/10.1126/science.1148777 |
| Summary: | The Turonian (93.5 to 89.3 million years ago) was one of the warmest periods of the Phanerozoic eon, with tropical sea surface temperatures over 35°C. High-amplitude sea-level changes and positive δ 18 O excursions in marine limestones suggest that glaciation events may have punctuated this episode of extreme warmth. New δ 18 O data from the tropical Atlantic show synchronous shifts ∼91.2 million years ago for both the surface and deep ocean that are consistent with an approximately 200,000-year period of glaciation, with ice sheets of about half the size of the modern Antarctic ice cap. Even the prevailing supergreenhouse climate was not a barrier to the formation of large ice sheets, calling into question the common assumption that the poles were always ice-free during past periods of intense global warming. |
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