• 作者： 陳汝勤; 黃清波
• 作者服務機構： 國立臺灣大學海洋研究所
• 中文摘要： 筆者提出有關微量元素和稀土元素的資料，以討論大屯火山區（萬里一帶），海岸山脈和綠島之安山岩的可能成因。大屯安山岩的稀土元素圖形為輕稀土元素富集，重稀土元素幾乎呈水平，而鑭／鐿比則落入鈣鹼系列範圍內。一般言之，海岸山脈西北部呈現矽質玄武岩系列特性，而東南部則為鈣鹼系列，此種島弧火成岩系列的分布，筆者認為是空間性的，而不是時間性的。綠島安山岩較海岸山脈及大屯火山區之安山岩有較高的銣、鍶、鑭、鈰、鋇、銫、鉿、釷、鈾和鑭／鐿比，綠島安山岩中不共溶元素的富集，顯示岩漿生成之深度較鄰近火成岩區為深。更新世時，臺灣北部安山岩的噴發，可能與菲律賓海板塊向西北方向隱沒而造成之部份融熔有關。而向東傾斜之南海板塊隱沒帶上所產生之岩漿則形成了都鑾山（海岸山脈）火山弧。 海岸山脈安山岩和綠島安山岩之間，不共溶元素和由鉀一氬定年所得之年齡有明顯的差異。因此，都鑾山火山弧和綠島之間的關係仍待進一步研究。
• 英文摘要： Trace elements and REE data are presented to diseuss the possible origin of andesites from the Tatunvolcano (Wanli district), the Coastal Range and Lutao. The Tatun andesites are LREE-enriched and show anearly flat HREE pattern. The La/Yb ratio of Tatun andesites fall within the range of calc-alkali series. Ingeneral, a tholeiitic pattern can be found in the northwestern part while a calc-alkali pattern in the south-eastern part of the Coastal Range suggesting that the distribution of the island are volcanic rock series isspatial rather than temporal. Lutao andesites have relatively higher Rb, Sr, La, Ce, Ba, Cs, Hf, Th, U andLa/Yb ratios than Coastal Range and Tatun andesites. The enrichment of incompatible elements in Lutaoandesites suggests that the magma generation depth may be deeper than the adjacent volcanic suites. ThePleistocene andesite eruptions in northern Taiwan may be related to partial melting of the northwesternlysubducted Philippine Sea plate. The magma generated at the South China Sea plate subduction zone dip-ping toward the east built up the Tuluanshan (i·e. Coastal Range) volcanic arc. The relationship between the Tuluanshan volcanic arc and Lutao remains to be studied since thereare distinct differences in the incompatible elements and the K-Ar ages between Coastal Range and Lutaoandesites.
• 中文關鍵字： geochemisstry; andesites; trace elements
• 英文關鍵字： --