Earth’s Cryosphere, 2012, Vol. XVI, No. 2, p. 23-29
PERMAFROST FORMATION AND DEGRADATION IN THE URENGOY AND KUYUMBINSKAYA AREAS OF SIBERIA. PART 2. INFLUENCE OF VARIATIONS IN THERMOPHYSICAL PARAMETERS OF FROZEN ROCKS ON TEMPERATURE AND HEAT FLOW DISTRIBUTIONS WITH DEPTH
Yu.I. Galushkin, K.А. Sitar*, S.V. Frolov*
Lomonosov Moscow State University, Earth Science Museum,119992, Moscow, Leninskie Gory, 1, Russia; yu_gal@mail.ru
* Lomonosov Moscow State University, Department of Geology,119992, Moscow, Leninskie Gory, 1, Russia; sitar_msu@mail.ru, serfgeo@yandex.ru
Numerical reconstructions of variations in distributions of temperature and heat flow with depth during the Pliocene–Holocene period of great climate variations have been carried out on the example of sedimentary sections of the Urengoy field in the West Siberian Basin (well 414) and the Kuyumbinskaya area in the East Siberian Platform (the Kamov swell, well 12). The calculations confirm that an increase in salt content in underground water from 1 to 30 g/l decreases the ice melting temperature just by 2 °С. At the other equal conditions, it results in a decrease in permafrost thickness almost by 100 m. The calculations demonstrate that a similar effect will take place also when the content of unfrozen water typical of sands is replaced by the one taking into consideration the change of rock lithology with depth. The modeling results demonstrate that the temperature and heat flow distributions with depth in the present-day sedimentary section of the basin, obtained with consideration of climate variations only during the last 50 000 years, will differ significantly from the distributions with the climate variations during the last 200 000 or 3 400 000 years. The corresponding estimations of the lower boundary of permafrost zone will differ by 2 and more times.
Key words: Permafrost, paleoclimate, basin modeling, unfrozen water content, temperature, heat flow.