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

本研究项目的部分成果已在相关期刊上发表，并在许多会议上发表。主要研究结果如下：1.在日本、中国南方和加拿大西部的浅海碳酸盐岩地层中发现了以蓝藻为主的多种多样的钙质微生物，并通过野外观察和显微镜观察证实了它们的分布范围从志留纪到第四纪（近代）。并且在不同的环境中作为重要的沉积物生产者和礁相的沉积物稳定剂和粘合剂出现。3.钙质微生物特别在后生动物造礁者的衰退和消亡的几个地质时期繁荣（例如，二叠-三叠纪界线、晚石炭世漫长而严酷的冰库气候），在这些环境破坏时期起着重要的造岩生物礁作用。4.在多个地质时代的浅海碳酸盐沉积中，发现了各种类型的钙-微生物礁相及相关的有机沉积构造。这些微生物沉积物沿着海底胶结物，形成了小尺度的礁相地形高点，因此，需要利用地球化学方法来更全面、定量地描述与钙微生物繁盛有关的环境因子（温度、盐度、大气CO_2压力、海平面波动等）的时间变化。我们研究项目的一些研究人员已经开始了以此为目标的新研究。

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.