BACTERIAL FORMS IN GLAUCONITES FROM UPPER CRETACEOUS DEPOSITS OF THE WEST SIBERIAN PLATE
Yu.N. Zanin, V.G. Eder, and A.G. Zamirailova
Institute of Petroleum Geology, Siberian Branch of the RAS, 3 prosp. Akad. Koptyuga, Novosibirsk, 630090, Russia
Keywords: Upper Jurassic, glauconite, bacterial forms, West Siberian Plate
Pages: 729-732
Abstract
Mineralized tubular capsules are widespread in glauconites of the Georgievka Horizon (West Siberian Plate), which dates from the upper Oxfordian, Kimmeridgian, and lower Volgian Stages. These capsules, which are supposed to be sheaths of cyanobacterial threads and coccoid forms, make up the glauconite grains (microconcretions). Earlier, mineralized (phosphatized) capsules of cyanobacterial threads were found in phosphorites of the Georgievka Horizon. It is likely that the mineralization of cyanobacterial mats led to the formation of stromatolites and oncolites of carbonate-manganese composition, found in the eastern West Siberian Plate. Thus, a conclusion is possible that the microbial forms, bacteria and cyanobacteria, played a leading role in the formation of authigenic minerals and rocks of the Georgievka Horizon of the West Siberian Plate.
|
