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| 作者 | 謝孟龍;鍾令和 |
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| 出版日期 | 201905 |
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| 著作名稱 | Multiple Late Quaternary (<14 ka) mass-wasting events recorded in a small alluvial terrace along the upper Tachia River, central-northern Taiwan
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| 會議論文集 | 2019台灣地球科學聯合學術研討會 |
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| 會議名稱 | 2019台灣地球科學 |
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| 會議地點 | 南港 |
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| 會議日期 | 20190516 |
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| 國際性會議 | N |
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| 主題 | 地質 |
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| 摘要 | Studies of ancient mass wasting in active Taiwan orogen have been focused on eastern and central/southwestern Taiwan where alluvial terraces >20 m and up to 250 m high are common. Hundreds of radiocarbon dates (mostly <15 ka) have shown that these large terraces, especially those consisting of >50 m-thick debris-flow gravels, were created by extremely large landslides with recurrence intervals of longer than ten thousands of years. This study, however, targeted on a ~5 m-high terrace in the upper Tachia River catchment (central-northern Taiwan) which has been generally geomorphically stable during historical times. Totally 15 radiocarbon dates from debris-flow gravel or fluvial sand have been obtained, revealing at least 4 mass-wasting events at <0.3, 3.9, 9.2, and 13.2 ka. The finding of multiple mass-wasting events from this small terrace suggests that its contributing catchment has been subject to low magnitude/high frequency landslides (but only the largest ones left records), in contrast to those producing large alluvial terraces elsewhere in Taiwan. We believe that this landslide characteristic reflects the dominance of slate/argillite in the study area, which has lower thresholds for erosion than eastern and central/southwestern Taiwan that consist of thick volcanic and sandstone, respectively. Mass-wasting events of 3.9, 9.2, and 13.2 ka in age, shown in this study, are also recorded in central Taiwan (the Chenyeolan River), forming the largest three alluvial terraces there, but have not been found in eastern and southwestern Taiwan. This spatial pattern suggests the existence of forces (probably large earthquakes) that triggered landslides over an area of 100 km in length from the upper Tachia to the Chenyeolan rivers. |
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| 全文 |  |
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| 系統號 | NO000005131 |
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