Finding of probable Tunguska Cosmic Body material:: isotopic anomalies of carbon and hydrogen in peat

Method of a search for traces of Tunguska Cosmic Body (TCB) material using layer-by-layer analysis of the isotopic composition of light elements in peat has been offered. Four peat columns sampled at the explosion epicentre indicated significant carbon and hydrogen isotopic effects in its near catastrophic layers. The shifts, opposite in direction, for carbon (Δ¹³C reaches +4.3‰) and hydrogen (ΔD reaches −22‰) cannot be attributed to any known terrestrial reasons (fall-out of terrestrial dust and fire soot; emission from the Earth of oil–gas streams; climate changes, humification of peat, and so on). Moreover, the isotopic effects are clearly associated with the area and with the time of the 1908 event. They are absent in the uppermost and the lowest peat layers and also in the control peat columns sampled at the remote places. Since calculated δ¹³C value for an admixture of carbon (+51–64‰) is very high, these effects may not be explained by contamination of peat with material similar to ordinary chondrites or achondrites, too. Such heavy carbon occurs in the most primitive CI and CM types of carbonaceous chondrites. However, C/Ir ratio in a cosmic admixture is 10,000 times as many as in CI chondrites that points to cometary nature of the TCB. The isotopic effects are in agreement with the increase of the Ir content observed in peat, but, at the same time, small content of Ir points to the low content of dust in the Tunguska comet that sharply differs it from Halleys comet.