Sediments and morphology of deep lakes of Central Tunguska Plateau (Krasnoyarsk krai, Evenkia): on the problem of the Tunguska Event at 1908

Abstract

The shape of the bottom and the thickness of sediments of small lakes Zapovednoye and Peyungda, located 50-60 km from the supposed epicenter of the “Tunguska Event” of 1908, were studied using echo-sounding and seisimo-acoustic profiling, and their age was estimated using ¹³⁷Cs, ²¹⁰Pb, ¹⁴C. It was revealed that both lakes have funnel shape with a depth of 60 and 34 m, respectively, and are similar in shape and size to Lake Cheko, which, according to some researchers, is an impact crater formed by a celestial body as a result of the “Tunguska Event 1908”. The examples of lakes Zapovednoye and Peyungda show that the shape of Lake Cheko is not unique to this area. The age of the bottom sediments of lakes Zapovednoye and Peyungda exceeds several thousand years. In the sediments of lakes Zapovednoe and Peyungda, a layer with a high content of terrigenous elements was identified, presumably formed due to the input of disturbed soil layer as a result of the massive fall of trees after the “Tunguska 1908”. Thus, the presence of two deep funnel-shaped lakes near the epicenter of the “Tunguska 1908” much older than 1908, casts doubt on the uniqueness of Lake Cheko, and therefore its impact origin. In addition, according to our estimate, the age of Lake Cheko is no less than 300 years, which contradicts the hypothesis of its origin as a result of the “Tunguska 1908”.