Carbonate deposition/dissolution and environmental changes through the earth histroy

1.研究活动举行了若干次研究会议和研讨会，以促进讨论和信息交流。在这些会议上阅读的论文都以年度报告或摘要卷的形式发表。我们还建立了一个碳酸盐研究数据库(CADBA)，收录了约18万篇文章。2.项目要点我们揭示了碳酸盐碳同位素组成在前寒武纪/寒武纪界线下方表现出强烈的净异常，而在界线上方则表现出强烈的正异常。这意味着浅海水域在边界之前富含有机碳源碳酸盐物种。根据锶同位素地层学，发现中新世礁灰岩的白云石化作用是在低海平面时期海水和大气水的混合作用下发生的。根据电子显微镜观察，我们提出了在细菌活动(细菌诱导的碳酸盐)的强烈影响下形成类橄榄的可能性。3.项目的影响通过会议的讨论和合作，启动和促进了几个合作研究项目。这项研究表明，阐明无机碳酸盐在生物矿化和不平衡沉淀过程中的重要作用，对于更全面地理解碳酸盐的沉淀和溶解是至关重要的。

1.Research ActivitiesNumber of research meetings and seminars were held to stimulate discussions and exchange of information. Paperd read at these meetings have been published as an annual report or abstract volums. We also established a data-base for carbonate study(CADBA), which includes approximately 180,000 articles.2.Highlights of the ProjectWe revealed that the carbon isotopic composition of carbonates shows strong netagive anomly just below the Precambrian/Cambrian boundary, and strong positive anomaly just above the boundary. This implies that the shallow sea water was enriched in organic carbon derived carbonate species just before the boundary. Based on the strontiumu isotope stratigraphy, dolomitization of the Miocene reefal limestonewas found to have been occurred by the mixing of sea-water and meteoric waters during the period of low sea levels.We have suggested the possibility that ooids might have been formed under strong influence of bacterial activity(bacterial induced carbonates), based on the electron microscope observations.3.Impact of the projectSeveral cooperative research projects have been initiated and stimulated through the descussion and cooperation at the meetings. This project has made clearl that the elucidation of a vital effects in biomineralization and disequibrium precipitation of inorganic carbonates are crucial for the fuller understanding of carbonate precipitation and dissolution.