Boreskov

MICROFOSSILS OF BACTERIAL, MUSHROOM AND ALGAL NATUREIN EARLY PROTEROZOIC OF AROUND THE BAIKAL SIBERIA(UDOKAN RIDGE AND PRISAYAN’E)Stanevich A.M.*, Postnikov A.A.**, Terleev A.A.**, Kornilova T.A.*, Popov N.V.**PP‐65*Institute of the Earth’s Crust, Lermontov Str, 128, Irkutsk 664033, Russia;e‐mail: stan@crust.irk.ru;**Trofimuk Institute of Petroleum Geology and Geophysics, Koptyug Ave 3, Novosibirsk630090, Russia; fax: +73833332301; e‐mail: postnikovaa@ipgg.nsc.ruFinds of eucaryotic nature fossils are rare in Early Proterozoic. The nature of microfossilsthis time is often ambiguous. It is connected with replacement of organisms by authigenic ordiagenetic minerals and coalification under influence of a heat at metamorphism.Microfossils, received by us, show a different degree of safety and a variety of sea organisms2 billion years ago. All samples are processed by acids for extraction organogenic fractions.Sterility of a material was provided with preliminary dissolution and the subsequentwashing. Naminga formation of Udokan complex of Udokan ridge consists of greysandstones and dark grey aleurolites. Radiochronological data from granites and diabaseswhich are breaking through Udokan complex, show an age interval 1,8‐2,0 billion years.Carbonaceous microfossils have been received at dissolution of aleurolites. Fine forms (3‐20 m) have been define, how the remains of chemolithotrophic bacteria and their colonies.Existence of eucaryotic algae has been assumed because of a find acritarch Leiosphaeridia cf.L. crassa (Naum.). 50 thin sections are studied. Arkose aleurolites and aleuro‐argillites havebeen certain. Ilmenomagnetite, neogenic hematite‐goethite and leucoxene clots contain incement of rock. Similar trichomes microfossils are present at the majority studied thinsections. More than 30 "filaments" have been found. Their width is 15‐20 m, less often 10‐15 and 25‐30 m. Their length changes from 50 up to 500 m, on the average 120 m.Trichomes were kept in the form of silhouettes. Their contours are executed by hydrooxidesof iron and sustained enough on length. Internal parts of "filaments" are filled of leucoxene.They are sometimes deformed and bended by clasts of quartz and feldspar. Taxonomicdefinition of trichomes is based on the sizes of forms. Their part corresponds to diagnosisBotuobia Pjat. because of the sizes 10‐30 m and 50‐500 m. More thin "filaments" havebeen certain as Leiotrichoides Herm. and Eomycetopsis Schopf. It is supposed, that theseremains have been taken down from coastal sites of development of stromatolites.249