碩士 / 國立臺灣師範大學 / 地球科學系 / 96 / We have performed 477 isotopic analyses on surface-dwelling foraminifers Globigerinoides sacculifer of Holes 1115B (9º11.382’S, 151º34.437’E；water depth 1149m) drilled from Solomon Sea during ODP Leg 180. 13C values range from 0.33‰ to 2.29‰ and 18O values range from -2.44‰ to -0.05‰. The chronology is based on correlation of the oxygen isotope record to ODP677, the magnetic stratigraphy, the last and first appearance datum of selected fossils, the age of the Australasian microtektite (793ka), and radioactive isotope dating. We have identified 81 marine oxygen isotope stages and have constructed a refined age model covering last 2.2 million years for equatorial western Pacific. The periodicities of eccentricity, obliquity, and precession are observed. The average sedimentation rate is 5.8 cm/kyr. Carbonate contents increase with decreasing sedimentation rates from 2.2 Ma to present. Changes in carbonate contents and sedimentation rates may be related the rifting of Woodlark Basin and associated increasing of water depth.
Both Mid-Brunhes Event and Mid-Pleistocene Revolution preceded by 1.1‰ decrease in 13C values are observed. This is consistent with previous study for South China Sea and may indicate that change in global carbon reservoir size was the major cause of the Pleistocene climatic transitions. However, the magnitude of the change in 13C values is different and may indicate the regional variability in carbon isotope.
Difference in 18O values between ODP 1115B (close to the southwest margin of modern Western Pacific Warm Pool) and ODP 806 (near the center of the WPWP) shows a periodicity of 41ky. Difference in 18O values between ODP 1115B and ODP 806 decreases from 2.2 Ma to 1.7 Ma and becomes stable since 1.7 Ma. Therefore, the modern WPWP hydrographic condition may have formed since 1.7 Ma. Difference in 18O values between glacial and interglacial of ODP 1115B was greater than those of ODP 806. This suggests the paleoceanographic condition may have changed due to fluctuation of southwestern margin of West Pacific Warm Pool and higher 18O values in ODP 1115B may indicate higher evaporation rate associated shift in ITCZ over Solomon Sea
| Identifer | oai:union.ndltd.org:TW/096NTNU5135013 |
| Date | January 2008 |
| Creators | 柯惠親 |
| Contributors | Horng-sheng Mii, 米泓生 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 85 |
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