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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/30878

Title: 沿著呂宋-沖繩破碎帶的地殼構造初步研究
A preliminary study of crustal structure along the Luzon-Okinawa Fracture Zone
Authors: Wei-Yu Lai
賴威宇
Contributors: NTOU:Institute of Applied Geosciences
國立臺灣海洋大學:應用地球科學研究所
Keywords: 西菲律賓海盆;呂宋-沖繩破碎帶;海底地震儀;地殼構造;P波速度模型
West Philippine Basin;Luzon-Okinawa Fracture Zone;Ocean Bottom Seismometer,OBS;crustal structure;P-wave velocity model
Date: 2012
Issue Date: 2012-04-13T07:52:02Z
Abstract: 2009 年台灣大地動力學國際合作研究(TAiwan Integrated GEodynamics Research, TAIGER)計畫中的Leg 4 航次,我們於西菲 律賓海盆置放海底地震儀並且炸測多頻道反射震測剖面。使用的是美 國哥倫比亞大學Lamont-Doherty 地球觀測所藍賽斯號研究船(R/V Langseth)進行人工震源炸測。本研究利用2009 年6 - 7 月在西菲律 賓海盆內東經123°~126°,北緯19.5°~23.5°之間,沿著東北-西南走 向炸測了一條長 550 公里的測線,總共28 顆海底地震儀在此測線上 佈放,海底地震儀測站與測站間隔 15 公里。實施炸測作業期間, 由於颱風Molave 的干擾,使得 R/V Langseth 總共炸測了三次才完 成整條測線。資料收集回來後,首先先將海底地震儀位置重新定位, 挑選海底地震儀水壓分量的折射波,配合多頻道反射震測,共同建立 西菲律賓海盆P 波速度模型。P 波速度模型顯示此一區域為地殼厚度 介於6-10 公里的標準海洋地殼,而下部地殼(P 波速度介於6.0-7.0 km/sec)成高低起伏之狀,類似火成岩體。由多波束測深儀的資料, 顯示區域內火山很多。而且擴張的山脊呈交互重疊狀態,類似現今東 太平洋海脊(East Pacific Rise)海底擴張中心高速張裂的結果。由研究 區內磁力條帶的年齡推算,可能介於40-50 MYBP 之間,擴張速率為 高速的8.8 cm/yr。頻繁的火山和交互相錯的擴張海脊,可能與45 MYBP 的太平洋板塊改變方向有關。西菲律賓海盆的擴張方向為東北 -西南向,而花東海盆為南-北向。這種擴張方向改變的證據,判斷與 西菲律賓海盆的逆時針方向旋轉的演化歷史有關。
During the Leg 4 of TAIGER experiment (June-July, 2009), a long MCS/OBS profile of 550 km was shot by R/V Langseth in the West Philippine Basin. We placed 28 short-period OBSs at a station-to-station distance of 15 km along this profile. This profile was designed to be 90 degree to the spreading fabric as previously mapped by the multi-beam echo-sounding data. Because of the Typhoon Molave, R/V Langseth shot 3 times to complete the whole track. The large air-gun sources and over-lapping shoots allow us to place the shoot geometry into a single-combined profile. An initial OBS model indicates that the Pn arrival can be traced up to 80 more km away from the OBS station center. In this study, P-wave velocity model show that the crust thickness in the study area is about 6-10 km, and belongs to the typical oceanic crust. The roughness in the 6.0-7.0 km/sec P-wave velocity may be associated with the dense volcanic bodies. The multi-beam echo-sounding data show a big amount of submarine volcanoes, and some over-lapping spreading ridges. This environment is similar to that of the present-day the Eastern Pacific Rise with high spreading rate of 9-10 cm/yr. Previous magnetic lineations indicate that the age of study area is about 40-50 MYBP and the spreading rate about 8.8 cm/yr. Numerous volcanoes and over-lapping spreading centers may be related to the motion change of Pacific Plate at about 45 MYBP. The direction change of the spreading centers between the West Philippine Basin (NE-SW) and Huatung Basin (N-S) suggest that the West Philippine Basin was in a counter-clockwise rotation through its tectonic evolution.
URI: http://ethesys.lib.ntou.edu.tw/cdrfb3/record/#G0M97860002
http://ntour.ntou.edu.tw/handle/987654321/30878
Appears in Collections:[應用地球科學研究所] 博碩士論文

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