Permafrost

asis for palaeolimnological reconstructions of former environmental and climate conditions of
the periglacial realm in eastern Siberia. By using sedimentological, geochemical, and
micropalaeontological proxy records, including the application of ecological transfer functions,
an interdisciplinary approach is followed to characterize the dynamics of lacustrine systems
related to Holocene climate variability.
Few lakes of tectonic-glacial origin are located at the Verkhoyansk Mountain margin.
These mostly oligotrophic lakes are dominated by siliciclastic muds with low abundances of
organic matter. Changes in grain-size characteristics indicate variations in fluvial sediment
runoff, possibly related to spring snow melt. The majority of Yakutian lakes are eutrophic and
occur in shallow closed to semiclosed thermokarst depressions and in deep alass basins.
Because of the semiarid climate setting, the lakes respond very sensitively to perturbations in
the hydrological balance, driven by summer precipitation and evaporation. On longer time scale,
pollen and chironomid records in the lacustrine sediments document an early Holocene climate
optimum between 8.0 and 4.5 ka BP with generally warm and wet summer conditions. For the
same time, a marked variability in the proportions of pelagic and litoral compounds of organic
matter point to cyclic lake-level fluctuations at centennial time scales, possibly related to
climate seesaws of summer Arctic Oscillation. As for the sub-Recent development of lake status,
the cycles show affinities to variations in sun-spot activity.
Key words: East Siberia, holocene climate, limnogeology, thermokarst, alass, lake status
Change on permafrost on northerneastern Antarctic Peninsula
under climate warming
E. Ermolin
(Instituto Antártico Argentino, Cerrito 1248 (C1010AAZ), Buenos Aires,
Argentina,E-mail:ivgen52@yahoo.com)
Abstract: In the Antarctic Peninsula, from the time meteorological measurements began in the
middle twentieth century, the air temperature was characterized by a general decrease. The main
and particular effects of the present climatic changes on periglacial environment in the
permafrost regions are summarized. The different geocryogenic conditions produce the
divergent relationship between climatic change and frozen ground. Our field survey was carried
out systematically during the last four years on Seymour (Marambio) and Vega Islands on the
ice-free areas. The drypolar climatic conditions of the area, with a mean temperature around -
8.5 °C ÷ -5.5 °C, are for the existence of continuous permafrost with a thickness that is
probably greater than 150 m. on ice-free ground surface.
The previous studies have been determined two most important cryoformations, epigenetic
y syngenetic observed in this region. Epigenetic cryoformation presents the dry frozen ground
and occupies the greater part of Seymour Island consists of Tertiary marine sediments, and high
volcanic plateau on Vega Island. Syngenetic cryoformation consists of ice-rich frozen ground
developed under permafrost environment during degradation of Last Pleistocene Glaciation.
Ice-rich permafrost zone on Seymour Island occupies comparatively isolated small areas such
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