Late Holocene cliff-top dune evolution in the Hengchun Peninsula of Taiwan: Implications for palaeoenvironmental reconstruction

摘要

The Fung-Chuei-Sha (FCS) cliff-top dunes, the only coastal cliff-top dunes known in Taiwan, are situated on a 70 m high, tectonically uplifted Quaternary marine terrace surface in the Hengchun Peninsula of southern Taiwan. The development of the FCS dune and its relationship with palaeoenvironmental changes are still unknown. The optically stimulated luminescence (OSL) dating approach utilizing a pIRIR150 (post infrared, infrared stimulated luminescence at 150 degrees C) single aliquot regenerative (SAR) dose protocol for K-rich feldspar, in combination with radiocarbon dates and high resolution sedimentological analyzes, have proven to be a powerful tool for reconstructing the depositional history of the FCS dune and the related palaeoenvironmental conditions during the late Holocene. This study identified three major aeolian sediment accumulation periods at similar to 4 ka to similar to 2.3 ka, similar to 1.8 ka to similar to 1.1 ka, and similar to 0.7 ka to similar to 0.4 ka, which are consistent with the cold/cooling periods identified from the palaeoclimate record of the Dongyuan Lake in southern Taiwan. Two palaeosurfaces and two short interruptions of sand accumulation indicate periods of surface stabilization at the FCS site. The OSL ages and radiocarbon ages from the dune, and the palaeoclimate data from Dongyuan Lake suggest that these surfaces developed at similar to 4.3 ka, similar to 2 ka, similar to 1 ka and similar to 0.3 ka. The palaeoclimatic conditions inferred from the FCS dunes are largely consistent with those reconstructed for the coastal dunes of the Fulong Beach area in northeastern Taiwan. This may indicate an over-regional pattern of dune formation primarily driven by strong winds of the Asian Winter Monsoon as the primary forcing factor for coastal dune development in Taiwan during the late Holocene.