中台灣造山運動帶河流縱剖面構造地形指標之量化分析; A Quantitative Analysis for Tectonic Geomorphology Indices of Longitudinal River Profile on the Orogeny of Central Taiwan

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Title:	中台灣造山運動帶河流縱剖面構造地形指標之量化分析;A Quantitative Analysis for Tectonic Geomorphology Indices of Longitudinal River Profile on the Orogeny of Central Taiwan
Authors:	李準勝;Lee Chun-Sheng
Contributors:	地球物理研究所
Keywords:	常態化坡降指數(SL/k);凹曲度(θ);常態化陡度( ksn);坡降指數(SL);流水下切動力模型;數學擬合函數;構造地形指標;normalized gradient index (SL/k);gradient index (SL);normalized steepness (ksn);concavity (θ);stream power model;mathematical fitting function;Tectonic geomorphology indices
Date:	2009-06-01
Issue Date:	2009-09-22 09:55:02 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	由於板塊構造活動速率相當緩慢，人類歷史的記載是無法反應長時距的變化，而構造地形指標具有反應較長時距構造運動特徵的性質。本研究的目的是以河道縱剖面的數學擬合函數和坡降指數，以及流水下切動力學模型為基礎的坡度與面積關連性等所得的各種構造地形指標的量化分析，來探索在中台灣的造山運動帶上，東西兩側不同的大地構造運動所呈現的差異性及其構造地形演化上的各種特性。數學擬合函數是以對數型和指數型兩種函數，來說明河道縱剖面形式的特徵與大地構造運動的關係。由各主支流河道縱剖面所得到常態化坡降指數(SL/k)的成果，標示在二維剖面與二維平面圖中，來探討受大地構造運動下其地形地貌的特性。坡度與面積關連性是以流水下切動力模型為基礎，由其凹曲度(θ:代表地貌特徵)和常態化陡度(ksn:代表地盤抬昇程度)兩個構造地形指標來探索構造地形的特徵。本研究得到結果如下： 1. 中央山脈東西兩側不同的數學擬合函數(西側多為對數型，東側多為指數型)和凹曲度(θ)指標，可以說明在中台灣造山帶的地形地貌上所呈現東西兩側的不對稱性。 2. SL/k可以反應河流構造地形的岩性、遷急點、連續峽谷地形、地盤活動性等，同時也反應河流流路與斷層構造幾何關係的地盤活動性趨勢。 3. 中央山脈兩側log(ksn)的平均值幾乎是趨於相同的數值，以及在中央山脈兩側的對數型與指數型擬合的判別係數值相近，說明中台灣的造山運動帶正處於均衡狀態。 4. 由本研究ksn和SL/k的量化分析結果，本研究得到四個分區的大地構造活動性趨勢為西部麓山帶地區>雪山山脈地區>中央山脈東翼地區>中央山脈西翼地區，以及近50~60年的平均降雨量亦或是與面積有關的流量對於的反應是沒有明顯的關聯性，因此在長時距地質時間的河流演化上，氣候和岩性不是控制河流演化的重要因子，而是大地構造運動。 Due to the plate movement is considerably slow, human history record is too short to identify landscape change for such a long time scale. However, tectonic geomorphology indices can display the characteristics of tectonic movement in a long time. Therefore, the purpose of this study is to evaluate the difference of tectonic movement and characteristics of tectonic evolution between east and west sides of the orogeny in Central Taiwan, by applying a quantitative analysis of geomorphic indices coupled with mathematical fitting function, gradient index and slope vs area relationship from stream power model. Both logarithmic and exponential function of mathematical fitting function were used to illustrate the characteristics of river longitudinal profile and the relationship with tectonic movement. Furthermore, normalized gradient index (SL/k) from the river longitudinal profile of main and tributary was used to plot the 2-D profile for illustrating the characteristics of landscape. Additionally, the concavity (θ: represented to the characteristic of landscape) and steepness ( : represented to the degree of rock lift) from the slope vs area relationship of the stream power model were further applied to examine the characteristics of tectonic movement. The results of this study are listed as following: 1. Different results for the mathematical fitting function were found, in which most of logarithmic function were found on the west side, and most of exponential function were found on the east side. Concavity (θ) also showed the asymmetric landscape of the orogeny in Central Taiwan. 2. Normalized gradient index (SL/k) can response the behavior of rock, knickpoint, continuous-gorge, the active of rock movement, as well as the relationship between geometry of the flow path and the active trend of rock movement. 3. Average log(ksn) and the coefficient of determination (R2) of exponential and logarithmic function were similar for both sides of Central Range. Therefore, this study implied that the orogeny of Central Taiwan is in a steady state. 4. According to the quantitative analysis of geomorphic indices coupled with and SL/k, the degrees of tectonic movement trend are Western Foothills Belt > Hsuehshan Range Belt > Eastern Backbone Ridges Belt > Western Backbone Ridges Belt. Furthermore, the average precipitation in the past 50~60 years and the flow versus the normalized steepness (ksn) index exhibit no remarkable relationship. This study suggested that the control factor of stream evolution is tectonic movement, not the resistance of rock stratum nor climate.
Appears in Collections:	[Graduate Institute of Geophysics] Electronic Thesis & Dissertation

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