利用重力資料探討台中盆地與埔里盆地之二維地下構造; The Density Structure Model of theTaichung and Puli basin of the Central Taiwan from the Gravity data

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Title:	利用重力資料探討台中盆地與埔里盆地之二維地下構造;The Density Structure Model of theTaichung and Puli basin of the Central Taiwan from the Gravity data
Authors:	林家全;Chia-Chuan Lin
Contributors:	地球物理研究所
Keywords:	埔里盆地;重力;Gravity;Puli Basin
Date:	2005-06-16
Issue Date:	2009-09-22 09:55:13 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	論文提要內容：一直以來，台灣中部布蓋重力低區大部份理論皆傾向於地殼增厚進而導致重力低區的形成，卻並未真正的考慮到接近地表的物質影響，但事實上，地表的地層所造成的重力效應卻大於深部構造所造成的影響，尤其在埔里盆地周遭大部份都是高密度的漸新世及始新世地層，卻又形成一大範圍的重力低區，底下勢必存在著特殊的構造。因此，為了了解形成中部地區布蓋重力低區的成因，本研究希望利用觀測重力資料並藉由Talwani的二維理論公式得到一合理的台灣中部二維地下構造。在初始模型的假設方面，利用中油在台灣中部的深部震測資料中的烏溪與濁水溪剖面做為初始模型，利用嘗試錯誤法慢慢改變模型直到模型理論中力值與觀測重力值相當。結果顯示中部地區埔里盆地白冷層下方最有可能存在中新世的地層，而不是以地表的漸新世地層為主，此中新世地層的存在正好將地表白冷層等漸新世地層所提高的重力值往下拉，甚至低於台中盆地沖積層所造程效應。本研究亦挑選幾條台灣中部地區前人之剖面，利用這些剖面得到應有的理論重力值與觀測重力值比較，結果發現在埔里盆地下單純以漸新世及始新世地層為主的剖面，其重力值高的誇張，此結果更加深了埔里盆地下並不只是漸新世地層逆衝上來為主，理應存在著低密度地層在埔里盆地下，造成重力低區的形成。 The most significant feature of the Bouguer anomaly of Taiwan is the lowest anomaly value(-61 mgal) in the central Taiwan. It covers the Taichung basin, Puli basin , and foothills a 80 x 80 km . It is reasonable to know the low anomaly value in Taichung basin is filled with sediments. But it shows low Bouguer anomaly in the Puli basin compacts by the high density Oligocene stratigraphy. So we want to know what structure is underneath the Puli basin. This research choose a profile which across Taichung and Puli basin to simulate the subsurface density structure of these them. There are good constrains in the Taichung basin such as boreholes and seismic data, but for lack of more detailed information in the Puli basin. We try to model the density structure underneath Puli basin and there are several possible models to explain the subsurface density structure.
Appears in Collections:	[Graduate Institute of Geophysics] Electronic Thesis & Dissertation

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