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C Study of Transient Events and of the Ventilation Rate of the Pacific Intermediate Water during the Last Deglaciation
| Content Provider | Semantic Scholar |
|---|---|
| Author | Jean-Claude Arnold, Maurice Bard, Edouard Anné Kallel, Nejib |
| Copyright Year | 2006 |
| Abstract | 14C analysis of monospecific samples of planktonic and benthic foraminifera were performed in deep-sea sediment cores from the Atlantic and Pacific Oceans by Accelerator Mass Spectrometry (AMS). These measurements demonstrate that the Younger Dryas cold event, first described in the north Atlantic, is also present at the same time in the north Pacific Ocean. The comparison of the 14C ages of planktonic and benthic foraminifera from the same sediment level in two Pacific cores shows that the ventilation time of the Pacific Ocean was greater than today during the last ice age, but significantly less than today during the deglaciation. INTRODUCTION During the last deglaciation, the earth's climatic system experienced tremendous variations. Between the last glacial maximum and now, the volume of the continental ice sheets decreased by more than 60%, most of the melting occurring in the Northern Hemisphere. The sea-surface temperature increased, noticeably in the high latitudes of both the Southern and Northern Hemispheres (Ruddiman & Mc Intyre,1981; Pichon et al, 1988). Finally, the deep-water circulation changed from a glacial mode, characterized by ventilated intermediate waters strongly separated from poorly oxygenated deep and bottom waters, to the present mode where deep and bottom waters are well oxygenated, whereas intermediate waters are all characterized by a strong oxygen minimum (Duplessy et al, 1988; Kallel et al, 1988). Details of the climatic evolution of the ocean during the last glacial to interglacial transition are recorded only in deep-sea sediment cores with a high sedimentation rate (?lOcm/1000 yr). In such cores, Duplessy et al (1981) recognized two major steps in the oxygen isotope record of benthic foraminifera; this has been interpreted as evidence that the ice caps, which covered northern Europe and northern America, melted in two phases separated by a pause which lasted 2 to 3 millennia. Ruddiman and Mc Intyre (1981) demonstrated that the deglacial retreat of polar waters from the northern Atlantic Ocean was a complicated time-transgressive process, which was not unidirectional. A polar water readvance, marked by a seasurface-temperature (SST) drop in the north Atlantic and called the Younger Dryas event, occurred at ca 10,500 yr BP, interrupting the general southeast to northwest retreat. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://journals.uair.arizona.edu/index.php/radiocarbon/article/download/1176/1181 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
