Record of Meso-and Paleozoic environmental change and biotic evolution in calci-microbial sedimnent

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Part of results of this research program have been published in relevant journals and presented at many conferences and meetings. Major results are summarized as follows ;1.Highly diverse calci-microbes, mainly of cyanobacteria, were recognized at many stratigraphic levels of shallow-marine carbonate units in Japan, but also in South China, western Canada, Ws confirmed their occurrence ranges in age from Silurian to Quaternary(Recent) through the field and microscopic examination.2.Calci-microbes were recognized in a wide range of shallow-marine carbonate facies, and occurs as significant sediment-producer in varied environments and sediment-stabilizer and -binder of reefal fades.3.Calci-microbes flourished especially in several geologic periods of decline and demise of metazoan reef-builders(e.g., Permo-Triassic boundary interval, Late Carboniferous prolonged and severe icehouse climate) and played a significant role as rock-forming biotas in these environment-devastated periods.4.Various types of calci-microbial reefal facies and related organo-sedimentary structures were reported from shallow-marine carbonate sediments of many geologic ages. These microbial sediments are considered as having built up small-scale topographic highs of reefa facies, along with submarine cements.Our results suggest that geochemical approaches needed in order to more thoroughly and quantitatively delineate temporal changes of environmental factors(temperatures, salinity, atmospheric CO_2 pressure, sea-level fluctuation, etc) in relation to flourish of calci-microbes. Some investigators of our research project have already begun hew researches with this aim.