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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/15224

Title: 南海北部斜坡地殼速度構造研究
The crustal velocity structure of South China Sea continental shelf
Authors: Cheng-Shun Chan
詹政順
Contributors: NTOU:Institute of Applied Geosciences
國立臺灣海洋大學:應用地球科學研究所
Keywords: 海底地震儀;南海;大陸斜坡;火山;P波速度構造
OBS;south china sea;continental shelf
Date: 2009
Issue Date: 2011-06-30T08:09:02Z
Abstract: 南海(South China Sea)為西太平洋地區最大的邊緣海,屬非對稱性的張裂盆地。從南海區域圖中可以得知,南海北邊與歐亞大陸及台灣為鄰,東邊相鄰的是呂宋島弧系統、巴拉望島及馬尼拉海溝,南邊是盛產石油的婆羅洲,西邊則與中南半島相鄰。一般認為南海的海底擴張大約發生在漸新世(約32 百萬年),於中新世(約17 百萬年)停止張裂。 本研究使用2007年9月,大陸礁層計畫在南海東沙群島東邊大陸斜坡區收集10座海底地震儀折/反射,多頻道震測反射資料及利用二維射線追蹤方法建立一高可信度之P波速度-界面地殼構造。本測線海底地震儀沿上部大陸斜坡(0.6~1.5公里)、下部大陸斜坡(1.5~3.5公里深)至海洋盆地(大於3.5公里深)施放,本測線長度在南海大陸斜坡共計約200公里長。 從本速度模型中可以發現皆有火山及火成岩體入侵(5.0~5.5 km/s)發生速度改變的現象;火山在大陸斜坡分佈,體積較小,但數量多;海洋盆地則有較大的火成岩體入侵發生。本測線速度模型在中部地殼之間有明顯的速度變化發生(5.5~6.5 km/s);配合精密水深資料顯示,在上部大陸斜坡火山林立,下部大陸斜坡之間有明顯的構造發生。南海被認為是一被動式大陸邊緣,但根據最新水深調查顯示,在本研究區域南海北坡有許多火山的形成,下部大陸斜坡方面則有許多因撓曲作用而造成的構造現象。本測線上部、下部大陸斜坡及海洋盆地的地殼厚度皆比其他海底地震儀測線來的薄,推測南海北部斜坡的岩漿活動不僅受到南海擴張的影響,而且受到陸上陸-陸碰撞發育形成的二斷裂帶在不同時期的影響,導致本研究區域在地形與地體構造的特殊性。
The South China Sea is the biggest marginal sea in Western Pacific area. It is an asymmetrical extensional basin. A general see-floor spreading history of the South China Sea state that the basin was began in Oligocene (about 32 million years ago) and stop in the Miocene (about 17 million years ago). A joint research of the Micro-Ocean-Bottom Seismometer (MicrOBS) and the Multi-Channel Seismic (MCS) profiles was investigated in September 2007 as part of the Continental Shelf Survey Program. We have collected 10 OBS refract/reflect data and multi-channel reflect seismic profile in the continent shelf, southeast of the Dongsha island. We conduct a two-dimension ray tracing method to set up P wave velocity analysis. The water depth of OBSs station are along upper continental slope (0.6~1.5 km), the lower continental slope (1.5~3.5 km) to the ocean basin (more than 3.5 km). The total length of profile is about 200 km. There are the volcanoes and igneous rocks invaded in the profile (Vp = 5.0~5.5 km/s) and altered the ray speed in the velocity model. The volcanic distribute in the continental slope is small volume but in large quantity. The ocean basin have bigger igneous rock intruded. There is an obvious velocity change (5.5~6.5 km/s) in middle crust underneath the OBS stations OBS106 ~ OBS107 in the linear velocity model; Combining with the multibeam bathymetry data, the volcanoes stand in great numbers in the upper continental slope, there are obvious structures between OBS stations OBS105~OBS107 in the lower continental slope. The South China Sea was considered to be a non-volcanic passive margin, but according to the new multibeam bathymetry data, the volcanoes were all over continental slope and the lower continental slope which has a general structure trend of E-W direction similar to the seafloor spreading direction. The crust thickness of continental slope and ocean basin from this study was thinner than the previous studies of P-wave velocity structure. This infer the magma activity in north of continental slope. The South China Sea was not only influenced by the see-floor spreading tectonics, but also affected by the continent-continent collision of the Indian/Australian-Eurasian collision. This is found in the particular topography and geology structures in north continental slope of the South China Sea.
URI: http://ethesys.lib.ntou.edu.tw/cdrfb3/record/#G0M95860017
http://ntour.ntou.edu.tw/ir/handle/987654321/15224
Appears in Collections:[應用地球科學研究所] 博碩士論文

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