At present the species of the genus <i>Ovatoryctocara </i>Tchernysheva, 1962 are important stratigraphic markers of the boundaries between the traditional lower and middle Cambrian strata of Siberia. However, the vague taxonomic concept of the species and the lack of clear illustrations, which might demonstrate intraspecies variability, make the solution of the stratigraphic objective difficult. In regards to these problems, the genus has been revised on the basis of collections from east Siberian sections. Emended diagnoses for <i>O</i>. <i>ovata </i>(Tchernysheva, 1960), <i>O</i>. <i>granulata </i>(Tchernysheva, 1962), <i>O</i>. <i>angusta </i>(Tchernysheva, 1962), including subspecies <i>O</i>. <i>angusta snegirevae </i>(Suvorova, 1964), and <i>O</i>. <i>doliiformis </i>Korovnikov & Shabanov, 2008 are provided. In addition, the similarity between Siberian representatives of <i>O. granulata </i>and the specimens from South China and Greenland is established, based on meraspid morphology. Revision of the species shows that in the River Molodo section, <i>O. granulata </i>appears 20–25 cm higher than was previously documented
A study of triobite distribution allowed a biostratigraphic subdivision of the Kuonamka Formation section exposed in the middle reaches of the Olenek River (18 km downstream of the village of Olenek). Through detailed description of the section, a biostratigraphic subdivision down to the level of biozones and faunal beds was performed. These are beds with Calodiscus–Triangulaspis annio, Delgadella ultima–Bergeroniellus expansus Zone, Lermontovia dzevanovskii–Neopagetina orbiculata Zone, Anabaraspis Zone, Cheiruroides arcticus– Pagetia horrida Zone, Kounamkites Zone, Triplagnostus gibbus Zone, and beds with Tomagnostus fissus–Paradoxides sacheri. These biostratigraphic subdivisions were correlated with regional zones of the Siberian Platform. The study also provides analysis of trilobite assemblages from the Lower/Middle Cambrian boundary interval, which was identified in the studied section and other previously described sections (Nekekit, Molodo, Boroulakh Rivers). In the studied section, the base of the Middle Cambrian is defined by the FAD of Cheiruroides arcticus, i.e., at the base of the Cheiruroides arcticus–Pagetia horrida Zone. This level correlates with a presumed lower boundary of Stage 5 of a new International Stratigraphic Chart for the Cambrian System.
The Opening Ceremony of the 33rd IGC, with the flag parade and singer Gisela Jackson performing.Participants mingling in the venue's main hallway, the "Geostreet" during the Icebreaker Party.
The former stratigraphic chart of the Cambrian in the Turukhansk–Irkutsk–Olekma region of the Siberian Platform was compiled in 1986 and approved in 1988. Large amounts of data were obtained from new wells drilled in the western and northern parts of the region during the preceding 20 years. Modifications necessitated by new data entail an indefinitely continuous series of revised facies zonation, recognition of new facies areas, regions and zone, as well as definition of a regional early Mayan stratigraphic hiatus. A new local stratigraphic division is the Olenchima Member (base of the Evenk Formation) underlain by a hiatus. The term Kochumdek Formation is no longer used in the Bakhta region and its lithologically distinct subformations (Yasenga, Moktakon, Mara, and Abakun) were raised to formation rank. The Olenchima Formation is no longer used in the Baikit zone; but instead, the Litvintsevo Formation was established here by correlation.
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