A mass-wasting dominated Quaternary mountain range, the Coastal Range in eastern Taiwan

Fluvial bedrock incision, which creates topographic relief and controls hillslope development, has been considered the key medium linking denudation and tectonic uplift of unglaciated mountains. This article, however, shows a different scenario from the Coastal Range in eastern Taiwan. This range, w...

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Bibliographic Details
Published in:Quaternary science reviews 2017-12, Vol.177, p.276-298
Main Authors: Hsieh, Meng-Long, Hogg, Alan, Song, Sheng-Rong, Kang, Su-Chen, Chou, Chun-Yen
Format: Article
Language:English
Subjects:
Eastern Asia
Geomorphology
Landscape evolution
Mass movement
Quaternary
Radiocarbon date
River terrace
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Summary:Fluvial bedrock incision, which creates topographic relief and controls hillslope development, has been considered the key medium linking denudation and tectonic uplift of unglaciated mountains. This article, however, shows a different scenario from the Coastal Range in eastern Taiwan. This range, with the steepness inherited from pre-orogenic volcanoes, has been subject to mass wasting even before its emergence above sea level no earlier than Middle Pleistocene. Numerous terraced alluvial fans/fan deltas record the ancient mass movements of the range, including rock avalanches. Multiple radiocarbon dates 1 km2. Alluvial terraces are typically exhibited close to the source ridges of mass movements, and strath terraces along the downstream parts of rivers. Both were created when enormous sediment supply had exceeded or matched the prevailing river transport capacity. This process, along with the protection by giant boulders from mass movement, disturbed the long-term incision trend of rivers in response to tectonic uplift. As a result, the observed Holocene bedrock incision at most sites has not kept pace with the tectonic uplift. The spatial contrast in mass-wasting histories further accounts for the great diversity of the terrace sequences, even in areas with similar tectonic and base-level conditions. •Mass wasting generated numerous alluvial fans/fan deltas around the range.•Fluvial/alluvial terraces are omnipresent in the range.•Fluvial/mass-wasting histories are reconstructed based on >90 radiocarbon dates.•Mass wasting exerts strong controls on river behavior.•The Holocene bedrock incision has not kept pace with tectonic uplift.
ISSN:0277-3791
1873-457X
DOI:10.1016/j.quascirev.2017.10.019