Late Pleistocene-Holocene coastal development of islands off Vietnam

Abstract

Relief and deposits of Vietnam shelf islands (Tkhanlam, Kaoptyaotyai, Koto, Kaotkhaotyai, Dongkho, Fongwong, Timatao Re, Che, Mung, Tyam, Kondao, Baikan, Fukuok, Tkhotyu, Tkhom) were studied. In the Late Pleistocene-Holocene these areas were the islands during transgressions, when the continent was submerged. The islands were connected to the continent during regressions. Coastal relief and deposits indicate the mark of Riss-Wurm and some Middle-Late Holocene transgressions and regressions. Transgressions were recorded in 10, 4–6, 3–4, 2.5–3, 1.5–2 m terraces, elevated benches and elevated coral reefs. Deposits of transgressive phases of Middle-Late Holocene with sea level rises from 0.5 to 3 m were dated: 5060–6800, 3357–4100, 2170–2435, 900–1200 years B.P. Regressions were accompanied by intensive eolian activities, downslope processes and erosional downcut of river valleys.