The Last 90 Ka Intermediate Water Circulation Evolution of Northwestern Pacific
| Autor: | Shu-han Chang, 張舒涵 |
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| Rok vydání: | 2015 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 104 Nowadays there is no deep water but only intermediate water formed in northwestern Pacific. On account of the intermediate water circulation in North Pacific plays an active role in buffering the global ocean heat transportation. Thus, the understanding of hydrological development of intermediate water is important. In this study, piston core MD01-2411 recovered from the Oyashio region was used to construct the past intermediate depth hydrology through stable isotope (δ18O, δ13C) and Mg/Ca ratio analyses based on benthic foraminiferal Uvigerina spp. Estimated age model suggests the core approximately reaching back to 94,000 years, and the sedimentation rate reveals a relatively steady deposition environment. The long-term changes of Oyashio intermediate water reflect the intense of intermediate water circulation in northwestern Pacific. The positive temperatures and salinity anomalies suggest the saltier and warmer water penetrated down to intermediate water depth while the North Pacific surface water becomes saltier and leads to a stronger Pacific meridional overturning circulation (PMOC) and deeper formation of intermediate water. Within glacial time, the occurrence of Heinrich events associated with decreased intermediate water temperatures. The cold and fresh subsurface water indicates the surface water sinking deeper at high latitudes in the North Pacific and suggests the better ventilation occurred during Heinrich events. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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