Boreskov

PP‐59BLACK SHALE BIOMARKERS FROM THE KUONAMKA COMPLEXOF THE EASTERN SIBERIAN PLATFORM AND ESTIMATIONOF CAMBRIAN MARINE BIOCOMMUNITY DIVERSITYParfenova T.M.Trofimuk Institute of Petroleum Geology and Geophysics SB RAS,Prosp. Akad. Koptyuga 3, Novosibirsk, 630090, Russia; parfenovatm@ipgg.nsc.ruIn the Botomian, Toyonian, and Amgian ages of the Lower and Middle Cambrian,anomalously organic‐rich sediments accumulated in the north and east of the SiberianPlatform [Kontorovich, Savitsky, 1970 and others]. They formed carbonaceous rocks of theKuonamka complex (Shumnaya, Kuonamka, Inikan, Sekten, and Sinyaya Formations). It issuggested that the most of lipid matter of Cambrian black shales has been derived fromremains of lower plants and bacteria, while the contribution of microfauna is much less. Thefirst attempt to estimate the microbiotic diversity in the Kuonamka time seas from variationin composition and distribution of biomarkers has shown that three communities ofmicroorganisms could be established [Parfenova, 2007]. The known research results havebeen taken as a basis of diagnostics of biocoenoses: steranes and tricyclanes are biomarkersof eukaryotes, and hopanes are biomarkers of prokaryotes [Ourisson et al., 1984; Peters,Moldowan, 1993; Revill et al., 1994]. Based on steranes/terpanes and tricyclenes/hopanesratios, the communities have been divided into predominance of planktonic‐algalmicrobiocenosis, community with predominance of bacterial organisms, and planktonicbacterialmicrobiocenosis. Recently, sterane, lanostane, and hopane hydrocarbons (HCs) ofthe Lower Cambrian Sinyaya Formation have been studied in detail [Parfenova et al., 2010;Parfenova, 2011 and others]. The results of investigation of the composition, distributions,and ratios of terpane HC from bitumen extracts of the Kuonamka, Inikan, and SinyayaFormations are shown in this work. Saturated HCs have been identified using gaschromatography‐mass spectrometry system Agilent 5973N. Comparative molecular analysismade it possible to propose for discussing the biomarker parameters of fourbiocommunities.The first biological community is characterized by the following parameters:steranes/terpanes ratio is higher or equal to 0.3; tricyclanes/hopanes ratio is higher than 1;steranes are generally dominated by cholestane and ethylcholestane; lanostanes and 28,30‐bisnorhopane (С 28 ) are absent; С 29 /С 30 hopane ratio is less than 1. The С 35 /С 34 homohopaneratio is lower than 1. This suggests [Peters, Moldowan, 1993 and others] that there was noanomalous hydrogen sulfide contamination of bottom water and sediments, from which theexamined carbonaceous rocks formed. These characteristics are peculiar to the organic236