Donnerstag, 17. Januar 2008

Pingos and lakes

Dzhangyskol is a small lake of glacial origin in the central part of the Altai Mountains in southern Siberia. Pollen stratigraphies and chronologies of two cores record the vegetational development of the area from the Late Glacial treeless landscape to the forest and steppe of today. The modern lake is a remnant of a much larger ice-dammed lake, which was reduced in size and then temporarily drained after diversion of the inflowing mountain meltwater stream, which had low d18O values. The dry lake floor allowed development of permafrost and small pingos (frozen mounds of lake sediments). With the onset of greater climatic humidity in the mid-Holocene, the input of local water with higher d18O caused a rise in lake level, drowning the earlier pingos. Growth of a broad fen on the margin of the lake led to formation of a modern pingo complex.

BLYAKHARCHUK et al. (2007): The role of pingos in the development of the Dzhangyskol lake–pingo complex, central Altai Mountains, southern Siberia. Palaeogeography, Palaeoclimatology, Palaeoecology Vol. 257, 4

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