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Abstract:
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All over the world, several Quaternary proxy data have been used to
reconstruct past sea levels, mainly radiocarbon or OSL dating of exposures of
marine facies or shore line indicators (e.g. Carr et al., 2010) as well as paleoenvironmental
indicators in lagoon or estuary sediments (e.g. Baxter and
Meadows, 1999). Estuaries and deltas develop at river mouths during
transgressive and regressive phases, respectively (Boyd et al., 1992). In
particular, the postglacial Holocene sea-level rise has contributed importantly to
the estuary-to-delta transition (Hori et al. 2004). By analyzing radiocarbon ages
of the basal or near-basal sediments of the world’s deltas, Stanley and Warne
(1994) showed that delta initiation occurred on a worldwide scale after about
8500–6500 years BP and concluded that the initiation was controlled
principally by the declining rate of the Holocene sea-level rise.
Worldwide there were different regional sea-level changes since the last
glacial maximum (LGM) (Irion et al., 2012). Along the northern Canadian
coast, for example, sea level has been falling throughout the Holocene due to
the glacial rebound of the crust after the last glaciation (Peltier, 1988). This is
comparable to the development in Scandinavia (Steffen and Kaufmann, 2005)
where sea level drops today. From about Virginia/USA to Mexico there is a
constant sea-level rise similar to the Holocene sea-level development of the
southern North Sea (e.g. Vink et al., 2007). From the border of Ceará/Rio
Grande do Norte down to Patagonia, indicators of Holocene sea level point to a
level that was up to 5 m higher than today's mean sea level (Angulo et al., 1999;
Martin et al., 2003; Caldas et al., 2006a, b) |