恆春半島的構造地形演化

Landscape dynamics of the Henghcun Penisula, southern Taiwan

張文和(Slawomir Jack Giletycz)

指導教授 ： 張中白

國立中央大學/地球科學學院/地球科學系/博士(2015年)

摘要

位於台灣最南端的恆春半島擁有最年輕的地形景觀。由於台灣的造山作用是由北向南傳遞，恆春半島保存了一套最年輕也最完整的岩層露頭。在如此年輕的地形，我們可觀察到非常活躍的構造活動，並藉由這些的構造地形特徵，分析此區域的構造活動歷史。
此博士論文的目標乃藉由描繪現今的地形演化特徵、方向及演化速率以了解恆春半島的構造活動。透過野外調查、數值高程模型的分析，並結合前人研究成果，以獲得地形特徵的參數，利用量化的資訊直接獲得構造地形之演化程度。流域盆地和河道特徵是此研究方法的主要目標，透過現階段的流域系統萃取遷急點的行為以得知該流域的古平衡情形，而遷急點向上游倒退的量值可提供地形變動的反應時間資訊。在研究的過程中，流域盆地的形貌亦受到河流地形襲奪演化影響，襲奪事件不只會更改流域盆地的參數，也提供其他地形演化資訊。
在此論文中的第二部分主要為恆春半島地質構造的繪製。綜合前人對恆春半島的地質調查結果及野外調查資料，建立了修正後的區域地質圖，特別在半島的西南部。透過野外觀察，為上新世至全新世的地層建立了新的構造概念，可成功解釋之前不能解決的地質問題並得到更完整的結論。

關鍵字

過渡地形 ； 造山帶 ； 台灣 ； 河流作用 ； 遷急點 ； 恆春斷層 ； 活動構造

並列摘要

Hengchun Peninsula is the youngest landscape in Taiwan. Due to southward propagating emergence of the island, the peninsula also outcrops the youngest formations in the orogen. In such juvenile topography, we are able to observe very dynamic geomorphic processes, likewise expect to locate relict landforms before their adjustment to new topographical settings.
The Hengchun Peninsula was a target of my doctorate survey. I tried to map the present conditions of the landscape evolution and track the directions, rates of the geomorphic processes. Based on fieldwork, DEMs (Digital Elevation Models) processing and profound synthesis of the previous publications, I expected to derive parameterization of the landforms features, which could direct a sense and enhance comprehension of the landscape evolution. Drainage basins and fluvial processes were the major subjects in my methodology, where through knickpoint behavior I extracted the paleo-equilibrium conditions from present stage of the drainage system. Then, knickpoints regression values give the response time of the landscape to the subsurface input. However during the survey I also recognized that the drainage basins are deformed by other feature that influence the landscape evolution- captures. The capture events not only distort the basins parameters but also give valuable information about relict landscape shrinkage. This phenomenon is apparent in the Hengchun Peninsula, where I was competent to map its range and input as another parameter of the landscape development.
The second part of my dissertation concerned the geological mapping of the Hengchun Peninsula. After synthesis of previous surveys over the peninsula’s geology and number of my field investigations, I built an updated geological map of the area. Especially in the southwestern part of the peninsula, my observation delivered new tectonic concept of the Pliocene to Holocene formations. This new approach benefited to explain few ‘not-solved’ issues and conclusively I believe it is the most complete geological map of the area till present.

並列關鍵字

transient landscape ； orogen ； Taiwan ； fluvial processes ； knickpoint retreat ； Herngchun Fault ； active tectonics

參考文獻

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