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Geomicrobiological Processes for Laminated Textures

2018; Springer International Publishing; Linguagem: Inglês

10.1007/978-981-13-1337-0_5

2197-9553

Akihiro Kano, Tomoyo Okumura, Chizuru Takashima, Fumito Shiraishi,

Geological formations and processes

A laminated deposit is a record of cyclic changes of physical, geochemical, and microbiological conditions. The laminated pattern is often quite regular. In lacustrine verves, regular seasonal changes in weather conditions accumulate a characteristic alternation of siliciclastic muddy particles and authigenic minerals. Based on patient search of the lamina counting and 14C dating, time series of geochemical and paleontological proxies in the lacustrine verves have decoded an excellent record of ancient climates (e.g., Nakagawa et al. 2003). Some stalagmites are also laminated annually, associated with seasonal change in physical and geochemical properties of dripwater. Distinct patterns in the drip rate, the saturation states, and fulvic acid content between summer and winter or between wet and dry seasons leave annual change in carbonate crystal fabrics and fluorescence (Shopov et al. 1994; Baker et al. 1999). Because U-Th isotopes support accurate dating, stalagmites have been used for paleoclimatic studies (e.g., Fairchild and Baker 2012). Another example of annual lamination is observed in tufas, non-hydrothermal carbonate precipitates developed in streams and rivers in limestone area. Origin of the lamination in tufas is somehow similar with that of the stalagmite lamination. However, tufas have one- or two-order wider lamination (or growth rate) than stalagmite. Because of the thicker lamination, tufas are available for higher-resolution analysis of the past climates (e.g., Kano et al. 2004).