https://scholars.lib.ntu.edu.tw/handle/123456789/37530
標題: | 碎屑鋯石同位素示蹤研究(I):以孟加拉盆地為例 | 作者: | 鍾孫霖 | 關鍵字: | 碎屑鋯石;同位素示蹤;構造活動;河流沈積;孟加拉盆地;detrital zircon;isotope tracers;active tectonics;alluvial rivers;Bengal basin | 公開日期: | 2005 | 出版社: | 臺北市:國立臺灣大學地質科學系暨研究所 | 摘要: | 大地構造活動和河流的侵蝕與沈積作用之間的互動,以及它們對區域乃至全球氣候、環境的影響 或反餽,多年來一直是國際地球科學前沿研究的主題之一,最近幾年更已儼然成為焦點,有關的 研究報導推陳出新,令人目不暇給,尤以Nature 在2003 年刊出的一系列論文可代表個中翹楚,反映 出國際領先團隊在相關領域的最新研究進展(詳見本計畫內容說明)。本研究計畫以申請人過去兩 年多來在西藏東南部地區的工作為基礎,擬利用鋯石的原位U-Pb 定年和Hf 同位素分析技術,測量 選採自孟加拉盆地晚新生代沈積物中的“碎屑鋯石”(detrital zircons),據以探討東喜馬拉雅造山結的隆升史和南亞三大河系(雅魯藏布江、布拉馬普特拉河及依洛瓦底江)之間的互動與演化關係。 若蒙補助,預期本研究將能利用採自當今地表上研究「造山–剝蝕交互作用」最佳的天然實驗室 的標本,針對上述焦點議題發聲,並提供嶄新的視野和重要的制約。 The interactions between tectonic uplift, river erosion and alluvial deposition are fundamental processes that have continued to shape the Earth’s landscape we see today. Understanding of the relations or causal links among these processes, which are on-going and particularly active in mountainous regions such as the Himalayas, has attracted wide interests involving not only geomorphology, sedimentology and structural geology, but also hydrology, river engineering and mitigation of natural hazards. In this project, we propose to explore the relations between active tectonics and alluvial deposition records around the eastern Himalayan syntaxis, by performing in-situ U-Pb dating and Hf isotope analyses of detrital zircons from the late Tertiary-Quaternary sedimentary formations from the Bengal Basin. The aims of this study include: (1) to test the famous “tectonic aneurysm” model for the formation of the Namche Barwa syntaxis, within which the Tsangpo River cuts a cross-strike gorge through the eastern Himalayas and heads south to the Brahmaputra River in the foreland; (2) to test the popular hypothesis of river piracy linked with the Namche Barwa tectonics such that the Tsangpo River was the upper reach of the Irrawaddy River and it got captured by the Brahmaputra River only recently, say, within 4-5 million years from now; and (3) to better understand the Indian monsoon’s evolution in the late Cenozoic and causal links between active tectonics and climate in this region based on the above two tests and evaluations of relevant geologic information. This project that involves investigations from high mountains (the roof of the Earth and sediment’s major source provenance) to foreland basin (part of the largest sedimentary sink in the world) would depend essentially upon our work in southeastern Tibet done in the past 2-3 years to constrain the source components and a field excursion to Bangladesh and NE India to be collaborated with local geologists for collecting samples. The proposed in-situ zircon U-Pb experiments will be performed at the SHRIMP-II lab in the Chinese Academy of Geological Sciences, Beijing, while the Hf isotope measurements using LA-MC-ICPMS still have to reply heavily upon a continued collaboration with the GEMOC center, Macquarie University, Australia, before the newly purchased state-of-the-art machine of ours is fully set up in this department. |
URI: | http://ntur.lib.ntu.edu.tw//handle/246246/11864 | 其他識別: | 932116M002014 | Rights: | 國立臺灣大學地質科學系暨研究所 |
顯示於: | 地質科學系 |
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932116M002014.pdf | 298.01 kB | Adobe PDF | 檢視/開啟 |
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