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Planktonic foraminfera;Stable isotope;South China Sea;Late Quaternary;Paleoceanography
|Issue Date: ||2013-07-31T08:43:17Z
|Abstract: ||摘要:本計畫預訂將基於過去本人參與的國科會整合型計畫“古全球變遷(PAGES)”與“國際海洋古全球變遷研究（IMAGES）”中的南海古海洋學初步研究成果，配合我國預定將於今年四月與法國合作利用Marion Dufresne號研究船在南海區域進行的IMAGES第三航次所探取的二支分別位於北坡和越南外海的高解析度，最近三十萬年長度的岩心記錄，對下列重要科學目標，進行為期一年的資料分析與研究。這些預定的工作及目標為（一）岩心浮游有孔蟲化石群豐度資料計量分析與表層海洋環境變化估測；（二）岩心樣品總碳量（TOC）和碳酸鹽重量比（CaCO3%）資料分析與高解析度時間地層模式的建立；（三）重建完整的，基於浮游有孔蟲化石群的最近三十萬年南海的古冬季與夏季季風記錄；並嘗試構築一初步的解釋模型以辨識其相同與相異的驅動營力。上述工作之完成將有助於未來後續南海岩心分析位址的選定；並期能進一步與鄰近低緯太平洋氣候變化的相關性展開初步探討。|
abstract:The IMAGES (International Marine Past Global Changes Study) program has been initiated internationally since the first of January, 1996, and offered a major chance for a large and rapid increase in our understanding of Quaternary paleoceanography and global climate change by using the information from studying marine sediment core records. As a formal full IMAGES member starting from August, 1996, the Consortium of Taiwan Institutions (CIT) (coordinated by National Taiwan University) has participated shipboard and shore-based research in IMAGES II cruise to southern Indian-Atlantic Ocean. This correspondence paper presents the scientific objectives designed for the cruise, with brief introduction to the recent research status and progress in Taiwan related to the cruise activities.< We present the 1996-1998 highlights of the Taiwan IMAGES program, with objectives and some of the preliminary results from the third cruise for the western Pacific and the South China Sea (IMAGES III/MD106-IPHIS Cruise). This cruise was successfully conducted during June, 1997, by cooperation of international scientists from six countries. This correspondence paper introduces specifically the primary scientific objectives of the South China Sea part of the cruise, which was mainly proposed and planned by scientists from Taiwan: toward better understanding on the Quaternary variability of the East Asia monsoon, Kuroshio Current, and western Pacific warm pool systems. A summary with brief description for the cores obtained from the South China Sea in this cruise is also presented.< High-resolution studies on a planktonic foraminifer core record from the South China Sea (SCS) (31-KL: 18.degree.45.4'N, 115.degree.52.4'E, 3360m) imply that there are ice volume forcing-driven changes as well as rapid high-frequency oscillations in western Pacific marginal sea climate of East Asia monsoons during the late Quaternary. The analyses of planktonic foraminifer faunal abundance data from the core, supplemented with age constraints from AMS /sup 14/C dating and .prtl./sup 18/O stratigraphy reveal striking variations in the relative abundances of the dominant taxa since 100,000 years ago in the isotope stage 5. Three faunal assemblages derived based on a Q-mode factor analysis make up over 95% of the variation within the core and have meaningful ecological significance when compared to those of the modern distributions and the relationships to ocean hydrographic environments.< Further detailed analyses indicate that the transfer function estimates of faunal SST show linkages with long-term trend (10/sup 4/-10/sup 5/ years) of global glaciation and also intermediate-term variations (10/sup 3/-10/sup 4/ years) in solar insolation changes for January at 60.degree.N. About 65,000 years ago, there is an observable change in the mode of SST variability which was previously reported from many low-latitude records. Over short-term variability (<10/sup 3/-10/sup 4/ years), the SST was punctuated by significant cold spikes that appear to correlate with rapid oscillation events as captured by ice core records. This pattern suggests rapid oscillations and an instability of surface ocean conditions of the SCS during the past 100,000 years.< This finding suggests that the SCS surface circulation and the East Asia winter monsoon systems are mainly driven by the variations of global glaciation levels and also by local solar insolation changes. The association of surface ocean cooling in the SCS with global short-term climatic events suggest rapid fluctuations in the strength of the East Asia winter monsoon, which maybe linked with the shifts in the latitudinal position of the westerly wind and the Siberia High Pressure system.<
|Appears in Collections:||[應用地球科學研究所] 研究計畫|
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