Jorge A. Strelin, Pablo A. Heredia Barión and Gerhard Kuhn
New minimum age of the postglacial transgression in Potter Cove, 25 de Mayo (King George) Island
References
del Valle, R. A., Montalti, D., Inbar, M., and Boaretto, E. (2007). Holoceno marino en la Península Potter, Isla 25 de Mayo, Antártida. Revista de la Asociación Geológica Argentina, 62: 35-43
Hass, H. C., Kuhn, G., Monien, P., Brumsack, H. J., Forwick, M. (2010). Climate fluctuations during the past two millennia as recorded in sediments from Maxwell Bay, South Shetlan Islands, West Antarctica. In: Howe, J. A., Austin, W. E. N., Forwick, M. y Paetzel, M., eds. Fjord systems and archives.
Geological Society of London, Special Publication 344: 243-260.
Sugden, D., and John, B. (1973). The age of glacier fluctuations in the South Shetland Islands, Antarctica. In: van Zinderen Bakker, E.M. (Ed.), Palaeoecology of Africa, the Surrounding Islands, and Antarctica. A.A. Balkema, Cape Town, pp. 139–159.
Watcham, E. P. (2010). Late Quaternary relative sea level change in the South Shetland Islands, Antarctica, PhD these, Durham University.
Marine Geology Am Alten Hafen 26 27568 Bremerhaven Germany
The inconsistency of the 9540 yrs BP age sample is clear. According to the obtained data the sedimentation rate of the muddy to sandy, near shore sediments is of 0.64 cm/year (period c- 7700 to 7200 yrs BP), similar to 0.71 cm/yrs measured in the cores PS69/335-1 and -2 in Maxwell Bay in the period 1100 to 200 cal yrs BP, about 446 m below the present see level (Hass et al. 2010).
The huge amount of penguin bones (C), that reaches the lower levels of the section (D), reveals that the penguin colony was located very close to this site and survived until the glacier override the place. Laternula s.p. shells generate escape structures crossing from F3 to F2 (B), indicating a high sedimentation rate. In the whole exposure it is clear how the glacier approached (gravity flows, ice rafted blocks) and finally overrode the marine and deltaic deposits, leaving a lodgment till (A) and deforming the previous facies.
According to our new radiocarbon ages, from Pingfo Norte section, the Holocene postglacial marine transgression initiated before 7650 cal yrs BP, reaching the highest, closely located, 14 m amsl marine terrace. The marine sedimentation of Potter Cove was interrupted by a glacier advance that postdated 7285 yrs BP.
It is generally accepted that the first Holocene marine transgression that reached the inner fiords of the South Shetland Islands occurred at least by 9540 +/- 235 cal yrs BP. This age is very important, since it provides the minimum on-land obtained age of the end of the last glacial period and start of the Holocene in this Antarctic sector.
Del Valle et al.
2007
We excavated an almost 4 m deep and 5 m wide section trying to replicate the oldest age obtained by Sugden and John (1973) below the 6 m ( a m s l ) m a r i n e terrace. Despite our and other authors radiocarbon samples c o m p r i s e m a r i n e shells, seaweed and penguins bones, the resulting ages are s t r a t i g r a p h i c a l l y consistent except for t h e 9 5 4 0 y r s B P obtained by Sugden and John (1973).
Cal yrs BP (reservoir correc0on Hope Bay)
