Deglacial and Holocene evolution of the Vietnam shelf: stratigraphy, sediments and sea-level change

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

“…Frechen et al 2004;Porat et al 2004). Schimanski and Stattegger (2005) calculated mass accumulation rates of 600-1,200 g/cm 3 per year in the shelf area for the time period of the early Holocene, which was caused by increased erosion in the Truong Son Mountains most likely due to intensified SW monsoon during the early Holocene. The outer barrier sands were deposited along the southeastern coastline of Vietnam between about 8 and 6 ka, which is synchronous with the maximum sea-level highstand after the postglacial marine transgression.…”

“…High sedimentation rates of 50-100 cm/ka and even 600-1,200 cm/ka were determined for short periods during the early Holocene (Schimanski and Stattegger 2005;Szczucinski and Stattegger 2001), as determined by numerical dating of sediments from the northern Central Shelf, which gave calibrated acceleration mass spectrometry (AMS) 14 C ages between 9.39 and 6.41 ka (n = 9) for this Holocene period. The accumulation of sediments was most likely triggered by enhanced erosion in the Truong Son Mountains owing to intensified SW monsoon, and by increasing the accommodation space on the shelf due to sea-level rise (Schimanski and Stattegger 2005). The chronology of Late Pleistocene sediments was provided by AMS 14 C data yielding numerical ages older than 13 ka (Schimanski and Stattegger 2005;Tanabe et al 2003).…”

“…The accumulation of sediments was most likely triggered by enhanced erosion in the Truong Son Mountains owing to intensified SW monsoon, and by increasing the accommodation space on the shelf due to sea-level rise (Schimanski and Stattegger 2005). The chronology of Late Pleistocene sediments was provided by AMS 14 C data yielding numerical ages older than 13 ka (Schimanski and Stattegger 2005;Tanabe et al 2003). An outer and an inner sand barrier can be distinguished along the southeastern and central coast of Vietnam.…”

“…The shelf off Central Vietnam is only 20 km wide. Thus, shoreline migration extended a few tens of kilometres inland following sea-level rise after the last glacial maximum (LGM) (Schimanski and Stattegger 2005;Tanabe et al 2003). During the Pleistocene, this area most likely experienced major periods of marine transgression and regression resulting in a repeated reorganisation of the depositional system.…”

Sedimentary development of the Pearl River Estuary based on seismic stratigraphy

“…9 shows the sea level curve for the PRE region over the past 15 ka. The sea level curve was constructed from a combination data including those for the offshore of Northern South China Sea continental shelf (Yim et al, 2006), the Sunda shelf of Southeast Asia (Hanebuth and Stattegger, 2004), the Vietnam shelf and surrounding areas (Schimanski and Stattegger, 2005), the Pearl River Delta region (Huang et al, 1982;Zong, 2004), the Pearl River Estuary (Chen et al, 1994;Yu et al, 2003), and the Bonaparte Gulf of Australia (Yokoyama et al, 2000) as a reference. It is noted that any sediment compaction effects were neglected by the curve.…”