碩士 / 國立臺灣海洋大學 / 應用地球科學研究所 / 96 / Abstract
High resolution records of oxygen and carbon isotope variations based on benthic foraminifer Uvigerina spp. in Core MD052928 （11°17.26’S, 148°51.60’E, water depth 2,250 m） of the past 300,000 years are established. The core was taken from offshore southeastern Papua New Guinea during IMAGES PECTEN Cruise ⅩⅢ. The deep water masses in this region contain the Circumpolar Deep Water and Antarctic Bottom Water.
The age model of the core was established by 10 AMS 14C dating based on planktic foraminifers, and graphic correlation with a LR04 stack compiled from global benthic δ18O records. The benthic δ18O values in this core range from ~1.5? to 0?, and the δ13C values vary from ~2.8? to 5.7?, and showing lighter δ18O and heavier δ13C in interglacial stages. We have performed cross-spectral analysis on the oxygen isotope record of core MD052928 with LR04 stack and found in-phase relationships on 100kyr, 41kyr, and 23kyr period cycles, indicating a good correlation with the LR04 stack.
Previous studies based on the variations of carbon isotope gradients between the Pacific and Atlantic suggest that the NADW formation was enhanced during stage1 and stage5.5. In these time intervals we found decreases of organic carbon contents and also decreased abundances of benthic foraminifer Uvigerina spp. in core MD052928. This suggests that the barren zones of Uvigerina spp. in the core are associated with low surface water productivity and/or increased deep water ventilation.
We also used the sea level record reconstructed from core TR163-19 in the eastern equatorial Pacific to evaluate to what extent our benthic δ18O variations are driven by the global ice volume effect. After removing the benthic δ18O variations that are related to the ice volume effect, which is a dominant component in our record, the residuals indicate local temperature and salinity effects. The heavier δ18O residuals appear to be correlated to the lighter δD that indicates low air temperature in Antarctic Ice Core Dome C. This relationship implies that the deep water temperatures in the western tropical Pacific are associated with Antarctic climate changes. Finally, we compared the benthic oxygen isotope record of MD052928 to an eastern equatorial Pacific record V19-30 and found that these two benthic records match each other to the first approximation, though subtle discrepancies between the two records may reflect either time scale / resolution or short episodes that are characterized by a heterogeneity of deep water mass properties in the equatorial Pacific in the past 300,000 years.
| Identifer | oai:union.ndltd.org:TW/096NTOU5135010 |
| Date | January 2008 |
| Creators | YIN-CHIEN LIAO, 廖尹千 |
| Contributors | MIN-TE CHEN, 陳明德 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 55 |
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