Timing of Holocene sand accumulation along the coast of central and SE Vietnam

Abstract

In Vietnam, the coastal sand barriers and dunes located in front of the steep slopes of the high rising Truong Son Mountains are sensitive to climate and environment change and give evidence for Holocene sea-level rise. The outer barrier sands were deposited shortly before or contemporaneous with the local sea-level high stand along the Van Phong Bay postdating the last glacial maximum (LGM). Optically stimulated luminescence (OSL) dating yielded deposition ages ranging from 8.3 ± 0.6 to 6.2 ± 0.3 ka for the stratigraphically oldest exposed barrier sands. Further periods of sand accumulation took place between 2.7 and 2.5 ka and between 0.7 and 0.5 ka. The youngest period of sand mobilisation was dated to 0.2 ± 0.01 ka and is most likely related to reworked sand from mining activities. At the Suoi Tien section in southern central Vietnam, the deposition of the inner barrier sands very likely correlate with an earlier sea-level high stand prior to the last glaciation. OSL age estimates range from 276 ± 17 to 139 ± 15 ka. OSL dating significantly improves our knowledge about the sedimentary dynamics along the coast of Vietnam during the Holocene.

Evolution of late Holocene coastal dunes in the Cauvery delta region of Tamil Nadu, India

“…Luminescence dating is proved to be an efficient tool to find chronology of coastal sediments and has been successfully applied to inland and coastal dunes (e.g., Reimann et al, 2010;Kunz et al, 2010a,b;Quang-Minh et al, 2010;Tsoar et al, 2009;Clemmensen et al, 2009;Porat and Botha, 2008;Bateman and Godby, 2004;Frechen et al, 2004;Ballarini et al, 2003). Radiocarbon dating has only limited use due to fewer occurrences of organic material in the sand units.…”

“…Coast parallel dunes are also important as it forms an effective barrier against natural disasters such as storms and Tsunamis. The formation and reactivation of dunes are mostly related to supply of sand, wind parameters such as direction, strength, frequency and duration as well as moisture content and grain size of the sediment (e.g., Pye and Tsoar, 1990;Tsoar, 2001;Thomas and Wiggs, 2008). Wind plays an important role in stabilising a dune by allowing vegetation growth on dune surface (winds having higher drift potential hinders the plant growth over dune surface) (Tsoar, 2001(Tsoar, , 2002Yizhaq et al, 2009) apart from moisture content of sand, and winds that exceed the velocity threshold will initiate movement of sand with certain grain size (Bagnold, 1941).…”

Sedimentological and ichnological implications of rapid Holocene flooding of a gently sloping mud‐dominated incised valley – an example from the Red River (Gulf of Tonkin)

“…A sandy estuarine system, however, started to form at about 8 ka, when the rate of relative sea‐level rise began to decelerate, nearly at the same time when the maximum flooding surface (MFS) formed (Tanabe et al ., ). Similarly, in the mouth region of the Mekong, the MFS is estimated to have formed around 8·2 ka (Nguyen et al ., ) and at the same time accumulation of coastal barrier sands started (Quang‐Minh et al ., ). Thus, the mouth of the Mekong also appears to have had an open, funnel‐shaped estuary with a subordinate development of sand bars.…”

Provenance, routing and weathering history of heavy minerals from coastal placer deposits of southern Vietnam

“…Direct evidence to support this can be found in optically stimulated luminescence (OSL) dating studies of stratigraphically oldest barrier sands exposed at Suoi Tien (10°57'16"N -108°15'30"E) and Hon Gom (12°41.64'N -109°45.27'E) (Fig. 1) (Quang-Minh et al, 2010) that include layers enriched in ilmenite and zircon. These gave deposition ages ranging from 8.3±0.6 to 6.2±0.3 ka BP, contemporaneous with the local postglacial maximum sealevel highstand.…”

“…This implies that rivers in the north of the study area deliver fresher ilmenite to the coast and offshore. Plot 5B compares ilmenite from Holocene sands (Quang-Minh et al, 2010) along the coast.…”