2015. "Mesozoic", Microbial Carbonates in Space and Time: Implications for Global Exploration and Production, D. W. J. Bosence, K. A. Gibbons, D. P. Le Heron, W. A. Morgan, T. Pritchard, B. A. Vining
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Extensive facies analysis of the outcrops located near Moscardón (Iberian basin, NE Spain) resulted in a precise reconstruction of the facies architecture of a Bajocian (Middle Jurassic) carbonate platform. Different types of microbialites occurred in the transitional area between the shallow and relatively deep carbonate platform domains, located above and below wave base level, respectively. The most significant volume of the micorbialites is found in the platform slope, located below wave base level, in a depth range of around 30–50 m. In the lower slope, during stages of rapid accommodation gain, the vertical aggradation of individual stratiform building blocks results in the formation of up to 25 m-thick microbial–siliceous sponge buildups. During stages of sea-level highstand the individual building blocks are dominated by lateral (down-slope) progradational accretion, resulting in flatter, lens-shaped buildups. The transition between the upper slope and the shallow platform area is characterized by microbial-encrusted intraclastic–bioclastic packstones. Microbial crust development helped to stabilize the seafloor, allowing the eventual accumulation and preservation of the sand-sized grains above wave base.
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Microbial carbonates (microbialites) are remarkable sedimentary deposits. They have the longest geological range of any type of biogenic limestones, form in the greatest range of different sedimentary environments, oxygenated the Earth’s atmosphere and produce and, furthermore, store large volumes of hydrocarbons. This Special Publication provides significant contributions at a pivotal time in our understanding of microbial carbonates when their economic importance has become established and the results of many research programmes are coming to fruition.
It is the first book to focus on the economic aspects of microbialites and in particular the giant pre-salt discoveries offshore Brazil. The volume contains papers on the processes involved in the formation of both ancient and modern microbialites and the diversity of style in microbial carbonate build-ups. Structures and fabrics from both marine and non-marine settings are discussed from throughout the geological record.