Climate Response to Orbital Forcing Across the Oligocene-Miocene Boundary
Spectral analyses of an uninterrupted 5.5-million-year (My)–long chronology of late Oligocene–early Miocene climate and ocean carbon chemistry from two deep-sea cores recovered in the western equatorial Atlantic reveal variance concentrated at all Milankovitch frequencies. Exceptional spectral power...
| 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)
2001
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1126/science.1058288 https://www.science.org/doi/pdf/10.1126/science.1058288 |
| Summary: | Spectral analyses of an uninterrupted 5.5-million-year (My)–long chronology of late Oligocene–early Miocene climate and ocean carbon chemistry from two deep-sea cores recovered in the western equatorial Atlantic reveal variance concentrated at all Milankovitch frequencies. Exceptional spectral power in climate is recorded at the 406-thousand-year (ky) period eccentricity band over a 3.4-million-year period [20 to 23.4 My ago (Ma)] as well as in the 125- and 95-ky bands over a 1.3-million-year period (21.7 to 23.0 Ma) of suspected low greenhouse gas levels. Moreover, a major transient glaciation at the epoch boundary (∼23 Ma), Mi-1, corresponds with a rare orbital congruence involving obliquity and eccentricity. The anomaly, which consists of low-amplitude variance in obliquity (a node) and a minimum in eccentricity, results in an extended period (∼200 ky) of low seasonality orbits favorable to ice-sheet expansion on Antarctica. |
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