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The Tunguska event and Cheko lake origin: dendrochronological analysis

Published online by Cambridge University Press:  23 October 2014

Fantucci Rosanna*
Affiliation:
Geologi Associati Fantucci e Stocchi, Montefiascone, VT, Italy
Serra Romano
Affiliation:
Dipartimento di Fisica e Astronomia, Università di Bologna, BO, Italy
Kletetschka Gunther
Affiliation:
Czech Academy of Sciences, v.v.i., Institute of Geology, Czech Republic Faculty of Science, Charles University in Prague, Prague, Czech Republic
Di Martino Mario
Affiliation:
INAF, Osservatorio Astrofisico di Torino, Pino Torinese, TO, Italy

Abstract

Dendrochronological research was carried out on 23 trees samples (Larix sibirica and Picea obovata) sampled during the 1999 expedition in two locations, close to the epicentre zone and near Cheko lake (N 60°57′, E 101°51′). Basal Area Increment (BAI) analysis has shown a general long growth suppression before 1908, the year of Tunguska event (TE), followed by a sudden growth increase due to diminished competition of trees that died due to the event. In one group of the trees, we detected growth decrease for several years (due to damage to the trunk, branches and crown), followed by growth increase during the following 4–14 years. We show that trees that germinated after the TE, and living in close proximity of Cheko lake (Cheko lake trees) had different behaviour patterns when compared to those trees living further from Cheko lake, inside the forest (Forest trees). Cheko lake trees have shown a vigorous continuous growth increase. Forest trees have shown a vigorous growth during the first 10–30 years of age, followed by a period of suppressed growth. We interpret the suppressed growth by the re-established competition with the surroundings trees. Cheko lake pattern, however, is consistent with the formation of the lake at the time of TE. This observation supports the hypothesis that Cheko lake formation is due to a fragment originating during TE, creating a small impact crater into the permafrost and soft alluvial deposits of Kimku River plain. This is further supported by the fact that Cheko lake has an elliptical shape elongated towards the epicentre of TE.

Information

Type
Research Article
Copyright
Copyright © Cambridge University Press 2014 

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