Sediments from Lake Cheko(Siberia), a possible impact crater for the 1908 Tunguska Evente

Cheko, a small lake located in Siberia close to the epicentre of the 1908 Tunguska explosion, might fill a crater left by the impact of a fragment of a Cosmic Body. Sediment cores from the lake's bottom were studied to support or reject this hypothesis. A 175-cm long core, collected near the center of the lake, consists of an upper ∼1 m thick sequence of lacustrine deposits overlaying coarser chaotic material. 210Pb and 137Cs indicate that the transition from lower to upper sequence occurred close to the time of the Tunguska Event. Pollen analysis reveals that remains of aquatic plants are abundant in the top post-1908 sequence, but are absent in the lower pre-1908 portion of the core. These results, including organic C, N and δ13C data, suggest that Lake Cheko formed at the time of the Tunguska Event

RAPPORTO SULLE INDAGINI DI SISMICA A RIFLESSIONE, GRAVIMETRICHE, MAGNETOMETRICHE, MORFOBATIMETRICHE E CAMPIONAMENTO FONDO MARE NELL\u2019 ARCO CALABRO (MAR IONIO) CAMPAGNA CALAMARE08

The study of the Calabrian Arc in the Ionian Sea is key to understanding of the geological processes in the Mediterranean Sea. We present the technical details and results of cruise CALAMARE08 with N/O Urania during spring 2008. We acquired a large set of geological and geophysical data, among them Multichannels Seismic and SBP, magnetometry, gravimetry, swath bathymetry and coring of sea bottom. 1. CNR, Istituto Di Scienze Marine, Bologna, Italy 2. Dipartimento Sc.della Terra, Universita- di Parma 3. Universita\u2019 di Bologna 4. Universita\u2019 di Roma-3 5. Universite\u2019 Brest 6. Istituto Nazionale di Geofisica e Vulcanologia, Roma-2, Roma, Italy 7. Istituto Idrografico della Marina, Genova Published 3.2. Tettonica attiv