Sedimentological Characteristics and Origins of Diatomaceous Deposits in the East African Rift System
Richard B. Owen, 2002. "Sedimentological Characteristics and Origins of Diatomaceous Deposits in the East African Rift System", Sedimentation in Continental Rifts, Robin W. Renaut, Gail M. Ashley
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Lacustrine diatomaceous deposits are widespread in the East African Rift System, occurring in Miocene to Holocene sedimentary units. Problems in their classification can be clarified with a common set of well-defined terms, including: diatomite, siliciclastic diatomite, subdiatomite, diatominc, and diatom-poor. Additional descriptors refer to lamination, fragmentation, and dissolution. Diatom taphonomy and assemblage alteration reflect sedimentation, interface, and analysis controls, including: dissolution, settling rates, fragmentation, and floral mixing. The spatial and temporal distribution of East African diatomaceous deposits, especially in the Kenya and Malawi Rifts, suggest specific models for the development of a variety of diatomaceous facies. The models are based on factors that control the availability of diatom nutrients, including: fluvial inputs, water depth, seasonality of rainfall, wind regimes and their influence on upwelling and overturn, and turbidity currents. In turn, these factors reflect tectonic and geomorphic setting, drainage basin geology and resultant water chemistry, and climatic setting.