Late Pleistocene to Holocene alluvial tableland formation in an intra- mountainous basin in a tectonically active mountain belt d A case study in the Puli Basin, central Taiwan Chia-Han Tseng a, e, * , Christopher Lüthgens b , Sumiko Tsukamoto c , Tony Reimann d , Manfred Frechen c , Margot B € ose a a Institute of Geographical Sciences, Freie Universit€ at Berlin, Malteserstr. 74e100, 12249 Berlin, Germany b Institute of Applied Geology, University of Natural Resources and Life Sciences, Peter-Jordan-Str. 70; A-1190 Vienna, Austria c Leibniz Institute for Applied Geophysics, Section 3: Geochronology and Isotope Hydrology, Stilleweg 2, 30655 Hannover, Germany d Soil Geography and Landscape Group & Netherlands Centre for Luminescence Dating, Environmental Sciences, Wageningen University, Droevendaalsesteeg 3, NL-6708 PB Wageningen, the Netherlands e Institute of Earth Sciences, Academia Sinica, P.O. Box 1e55, Taipei 115, Taiwan article info Article history: Received 12 February 2015 Received in revised form 6 November 2015 Accepted 7 November 2015 Available online 25 November 2015 Keywords: Intra-mountainous Puli Basin Tableland Luminescence dating River and valley development Tectonic vs. climatic forcing abstract The morphology in Taiwan is a product of high tectonic activity at the convergent margin and East Asian monsoon climate. Tablelands are prominent geomorphic features in the Puli Basin in central Taiwan. These tablelands provide an archive to understand links between past climatic evolution and tectonic events resulting in the formation of the present-day landforms. To establish a geochronological frame- work for the alluvium underlying the tablelands in the Puli Basin, optically stimulated luminescence dating was applied to obtain burial ages. The numerical data indicate an accumulation phase of alluvial fans in the Late Pleistocene to Early Holocene transition. The study area in the Taomi River catchment, an obvious longer precursor of the Taomi River, originating from west of the Yuchih Basin, transported the sediments forming the present-day southern tablelands. During the PleistoceneeHolocene transition, the climate changed to wetter and warmer conditions, so that slope processes might have changed and an increasing transport in the fluvial system was stimulated. Fluvial and fan terraces in other river catchments in Taiwan also indicate a period of increased fluvial transport and deposition. A geomorphic evolution model in the Puli Basin is reconstructed on the basis of the chronological framework and of sedimentological features. Fluvial processes controlled by climatic change and accompanied by tectonic activities have created the diverse topography in the Puli Basin. © 2015 Elsevier Ltd. All rights reserved. 1. Introduction The Taiwan orogenic belt is characterized by active rock uplift (e.g., Willett et al., 2003; Lee et al., 2006) caused by an ongoing convergence between the Eurasian Plate and the Philippine Sea Plate since the Late Miocene (e.g., Biq, 1989; Teng, 1990). The present-day climatic background can be characterized as a sub- tropical humid East Asian monsoon with intense rainfall including tropical storms and typhoons (e.g., Siame et al., 2011; Ching et al., 2011). Tablelands are one of the characteristic landforms in Taiwan. They consist of alluvial material deposited in fan-like features. They occur at the western plain of Taiwan and as tectonically influenced landforms they represent the foothills. But they also developed mainly in tectonically induced intra-mountainous basins formed by active tectonic processes (e.g., Hayasaka,1930; Tomita,1951; Huang et al., 2000; Chen et al., 2001; Wilcox et al., 2011). Therefore ta- blelands are the result of exogenic and endogenic processes and require a careful evaluation of tectonic and climatic influences. The tablelands in Taiwan were first described systematically in terms of morphology, lithology, and pedology by Tomita (1937). Lin (1957) assumed that sediments underlying the tablelands and terraces were deposited as early as in the beginning of the Qua- ternary. In the past two decades, studies focused more on * Corresponding author. Institute of Geographical Sciences, Freie Universit€ at Berlin, Malteserstr. 74e100, 12249 Berlin, Germany. E-mail address: ch.tseng@daad-alumni.de (C.-H. Tseng). Contents lists available at ScienceDirect Quaternary Science Reviews journal homepage: www.elsevier.com/locate/quascirev http://dx.doi.org/10.1016/j.quascirev.2015.11.006 0277-3791/© 2015 Elsevier Ltd. All rights reserved. Quaternary Science Reviews 132 (2016) 26e39