Integrated 3-D Structural Mapping in the Southern Taiwan Slate Belt: Implications for Basal Accretion and Orogenic Growth

This study integrates airborne LiDAR, 3-D structural mapping, satellite imagery, UAV observations, and field investigations to reconstruct the regional structural architecture of the southern Taiwan Slate Belt. In this densely vegetated and rugged mountain belt, conventional geological mapping is strongly limited by discontinuous exposures. High-resolution LiDAR-derived bare-earth topography provides a way to trace bedding, metamorphic foliation, and major structural lineaments continuously across areas that are otherwise difficult to investigate.

The resulting 3-D mapping reveals a previously unrecognized ~10-km-wavelength fault-breached synclinal structure and provides the first clear constraints on the three-dimensional trace of the Kuaiku out-of-sequence thrust. By integrating these new structural observations with paleo-thermal and geochronologic information, the study supports an orogenic evolution involving basal accretion, nappe stacking, penetrative deformation, and out-of-sequence thrusting.

More broadly, this work demonstrates how LiDAR-based 3-D geological mapping can extend structural interpretation far beyond isolated field exposures. It provides an effective approach for investigating the internal architecture and growth of active mountain belts, particularly in strongly deformed and densely vegetated regions where conventional mapping alone is insufficient.

本研究整合空載 LiDAR、三維構造製圖、衛星影像、無人機觀測與野外地質調查，重新解析南部中央山脈板岩帶的區域構造架構。中央山脈地形陡峭、植被茂密，傳統地質調查多受限於公路、河谷及零星露頭，因此很難完整追蹤區域尺度的地層與構造。利用高解析度 LiDAR 裸地地形，可以在三維環境中連續辨識層面、變質葉理及其他構造線形，大幅延伸傳統野外地質製圖的空間範圍。

研究結果辨識出一個過去未被完整認識的約 10 公里尺度斷層切穿向斜構造，並首次對重要的檜谷序列外逆衝斷層之三維延伸提供明確的構造限制。進一步結合古溫度與年代資料後，結果顯示基底增積、褶皺逆衝岩席疊置、穿透性變形與序列外逆衝作用，共同控制南部臺灣造山帶的地殼增厚與造山楔成長。

這項研究的重要性不僅在於重新理解中央山脈的構造演化，也展示了 LiDAR 三維地質製圖在植被茂密、露頭有限及構造複雜地區的應用潛力。它讓地質構造的解析從零散露頭觀察提升到連續的三維區域尺度，為理解臺灣及其他活動造山帶的內部構造與成長機制提供新的研究途徑。

Citation:

Chen, Y.-P., Chan*, Y.-C., Wang, Y., Chen, C.-T., Wei, W.-T., & Hsieh, Y.-C. (2026). Integrated 3-D structural mapping in southern Taiwan Slate Belt: Implications for basal accretion and orogenic growth. Geosphere. Geological Society of America. https://doi.org/10.1130/GES02927.1. (*corresponding author)