Schellmann, Gerhard; Radtke, Ulrich:

Ausmaße und potentielle Ursachen holozäner Meeresspiegelveränderungen an der patagonischen Atlantikküste (Argentinien)

In: Coastline Reports : Von der Geoarchäologie über die Küstendynamik zum Küstenzonenmanagement, Jg. 9 (2007), S. 103-114
ISSN: 0928-2734
Zeitschriftenaufsatz / Fach: Geowissenschaften
Rektorat und Verwaltung » Rektorat
Abstract:
A detailed sequence of elevated Holocene beach ridge systems, littoral and fluvio-littoral terraces is
preserved at different coastal sites along the Patagonian Atlantic coast between Bahía Vera (44°S)
in the North and San Julián (49°S) in the South. Their surface elevation above extreme high tide
water level (hTw) increases with age and with wave and storm exposition of the coastal
environment where they have been formed. In general, older beach ridges are more elevated than
the younger ones, but younger beach ridges may be more elevated than older littoral or fluviolittoral
terraces, which have developed in a low wave energy coastal environment. The ages of the
various Holocene littoral accumulation forms are determined by numerous radiocarbon dating of in
situ articulated shells within the littoral deposits.
The various Holocene shorelines are due to different stages of relative sea-level changes. The early
Holocene sea-level rise reached the Patagonian Atlantic coast about 8100 14C BP, when sea level
was less than 3 m lower than during the following Early Middle Holocene transgression maximum.
The later exists between 6900 to 6200 14C BP. Afterwards a significant sea-level decline of approx.
1 m to a second sea-level highstand between 5940 and 2600 14C BP occurs. In the following 300
14C years an additional strong sea-level fall of about 1 to 2 m happened. Then sea level has
declined slowly up to the modern level. Both distinct Holocene sea-level falls may be the result of
eustatic sea-level changes, whereas the general trend of sea-level lowering since the Early Middle
Holocene transgression maximum can be explained by a slow hydro-isostatic uplift (approx. 0.3 –
0.4 m/ka) of the Patagonian Atlantic coast.