The Tunguska event and Cheko Lake origin: dendrochronological analysis

0444565 - GLÚ 2016 RIV US eng J - Journal Article
Fantucci, R. - Serra, R. - Kletetschka, Günther - Di Martino, M.
The Tunguska event and Cheko Lake origin: dendrochronological analysis.
International Journal of Astrobiology. Roč. 14, č. 3 SI (2015), s. 345-357. ISSN 1473-5504. E-ISSN 1475-3006
Institutional support: RVO:67985831
Keywords : cosmic body impact * collapse crater * dendrochronology * Tunguska * tree rings * Russia * Siberia
Subject RIV: DB - Geology ; Mineralogy
Impact factor: 1.184, year: 2015

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 degrees 57, E 101 degrees 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.
Permanent Link: http://hdl.handle.net/11104/0247072