Литосфера (Aug 2017)
Biogenic siliceous accumulation in Early Paleogene marine basins of Western Siberia: Factors and stages
Abstract
Factors and stages of biogenic siliceous accumulation rocks in the Transuralian region and Western Siberiain during Early Cenozoic. Analysis, systematization, generalization of lithological and paleontological data on the basis of geological survey and exploration field works for opal cristobalite raw materials. The main paleogeographic factors of the distribution of siliceous deposits of the Serov and Irbit formations are determined, as well as the main stages of biogenic siliceous accumulation within the Transuralian and Western Siberia regions. Based on the analysis and systematization of the new data, and updated paleogeographic schemes of previous researchers the dynamics of the basin have been reconstructed and the factors that controlled the evolution of the new identified facies zones were established. Biogenic siliceous accumulation in Western Siberia took place in four stages: Danian, Tanetian, Ypresian and Ypresian-Lutetian. The intensity of the siliceous accumulation began to increase in Ypresian, reached a maximum at the end of the Lutetian. The main causes of biogenic accumulation were extensive marine links with the basins of the World Ocean, upwelling and water movement, the developed hydrological network, a favorable tectonic regime, which caused a weak terrigenous dilution of sediments. Sedimentogenesis of opal-cristobalite rocks occurred in the absence of a significant influence of volcanic processes. The main differences between the northwestern and southeastern parts of the basin in the era of accumulation of diatomaceous ooze consisted of a different chemistry of the waters and terrigenous demolition of the southern and northern seas. The combination of the depth of the basin along the Urals and the minimal introduction of terrigenous material determined the considerable power of the photosynthetic zone, which together with an excess of nutrients promoted the luxuriant development of diatom flora here. Early Paleogene biogenic siliceous accumulation in Western Siberia, along with similar processes in the North Atlantic, to some extent preceded the global Eocene stage of siliceous accumulation.
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