| Title | Middle Miocene ice sheet dynamics, deep-sea temperatures, and carbon cycling; a Southern Ocean perspective |
| Author | Shevenell, A.E.; Kennett, J.P.; Lea, D.W. |
| Author Affil | Shevenell, A.E., University of California, Santa Barbara, Geological Sciences and Marine Science Institute, Santa Barbara, CA |
| Source | Geochemistry, Geophysics, Geosystems - G3, 9(2), Citation Q02006. Publisher: American Geophysical Union and The Geochemical Society, United States. ISSN: 1525-2027 |
| Publication Date | 2008 |
| Notes | In English. 51 refs. GeoRef Acc. No: 287218. CRREL Acc. No: 63000050 |
| Index Terms | 20080209 |
| Abstract | Relative contributions of ice volume and temperature change to the global ~1% delta 18O increase at ~14 Ma are required for understanding feedbacks involved in this major Cenozoic climate transition. A 3-ma benthic foraminifer Mg/Ca record of Southern Ocean temperatures across the middle Miocene climate transition reveals ~2 ± 2°C cooling (14.2-13.8 Ma), indicating that ~70% of the increase relates to ice growth. Seawater delta 18O, calculated from Mg/Ca and delta 18O, suggests that at ~15 Ma Antarctica's cryosphere entered an interval of apparent eccentricity-paced expansion. Glaciations increased in intensity, revealing a central role for internal climate feedbacks. Comparison of ice volume and ocean temperature records with inferred pCO2 levels indicates that middle Miocene cryosphere expansion commenced during an interval of Southern Ocean warmth and low atmospheric pCO2. The Antarctic system appears sensitive to changes in heat/moisture supply when atmospheric pCO2 was low, suggesting the importance of internal feedbacks in this climate transition. |
| URL | http://hdl.handle.net/10.1029/2007GC001736 |
| Publication Type | journal article |
| Record ID | 84643 |