• 作者： 汪中和; 余芬英; 沈四杰; 黃瑞耀; 陳汝勤
• 作者服務機構： 中央研究院地球科學研究所; 臺灣電力公司放射試驗室; 工業技術研究院量測技術發展中心
• 中文摘要： 本研究以取自菲律賓海盆的二支重力式岩心（PSG-3及PSG-8)作了鈾及釷同位素分析。其沈積物中鈾及釷的含量分別是0.6~1.3 ppm及3.7~7.4 ppm。本研究並以釷－230過剩法及釷－230/釷－232比值法計算這二支岩心在過去十五萬年以來的平均沈積速率。岩心PSG-3的沈積速率約為每千年15 mm，而岩心PSG-8則為每千年6mm。由這兩種方法對同一支岩心導出同樣的結果顯示釷－232在岩心所涵蓋的時間內是連續均勻的沈積在菲律賓的深海盆。本文亦討論沈積速率與岩心採樣深度間的關係。
• 英文摘要： Deep sea sediments of two gravity cores (PSG-3: 17°22'N 125°14'E, water depth: 3992 m; PSG-8：17°05'N 128°24'E, water depth: 5520 m), taken from the Philippine Sea, were analyzed for their uraniumand thorium contents. Uranium and thorium concentrations ranged from 0.6 to 1.3ppm and 3.7 to 7.4ppm, respectively. Average sedimentation rates over the last 150,000 years have been estimated for thesetwo cores using the excess- Th and excess- Th/ Th methods. The rates range from 6 mm (for PSG-8)to 15 mm (for PSG-3) per thousand years and are depth dependent. The agreement between rates estimat-ed from excess- Th and excess- Th/ Th methods shows that the supply of Th may be constant inthis area. When compared with sedimentation rates estimated by the Deep Sea Drilling Project over the lastseveral million years, the rates have undergone no significant changes for the basin deeper than 4000 m.
• 中文關鍵字： uranium; thorium; isotopes; sedimentation rates; the Philippine Sea
• 英文關鍵字： --