海洋沉积物中自生碳氟磷灰石成因研究进展

A review on genesis of authigenic carbonate fluorapatite in marine sediments

  • 摘要: 自生碳氟磷灰石(CFA)是海洋沉积物中重要的磷汇,也是海底沉积型磷矿的主要含磷矿物。解析CFA的成因对了解地质历史时期海洋生产力变化、磷循环模式及其全球气候环境效应等具有重要的科学意义。本文在比较全面地收集、整理已有海洋沉积物中自生碳氟磷灰石成因研究相关文献和资料的基础上,通过综合性的比较分析,全面地总结了有关海洋沉积物中CFA形成的物质来源、形成环境及沉淀机制的认识,分析了包括有机质的微生物降解、铁羟基氧化物对磷酸盐的吸附与释放、鱼类硬质碎屑的溶解、大型硫化细菌对多聚磷酸盐的储存与释放等有关磷富集的过程,揭示了氧化还原条件的波动等对磷富集的影响。同时,本文强调磷酸钙(CaP)前体的存在及与CFA形成之间可能的关系,阐释CaP前体在碳酸钙表面的界面耦合溶解-沉淀机制可作为CFA交代成因的微观证据,并明确了交代成因CFA的多种鉴别标志。最后,希望依靠海洋科技的进步以及多学科的交叉研究,提出未来进一步深入研究海洋沉积物中自生CFA成因与分布的重要方向。

     

    Abstract: Authigenic carbon fluorapatite (CFA) is a crucial phosphorus sink in marine sediments and is the primary phosphorus-bearing mineral in submarine phosphorites. Understanding the genesis of CFA is of great scientific significance for understanding the changes in marine productivity, phosphorus cycling, and global climate and environmental effects throughout geological history. We overviewed the material sources, formation environment, and precipitation mechanisms of CFA in marine sediments. The enrichment of phosphorus in porewater involves the microbial decomposition of organic matter, the adsorption and release of phosphate by ferric oxyhydroxides, and the storage and utilization of polyphosphates by large sulfide bacteria. Fluctuations in redox conditions exert a significant influence on these processes. The formation of calcium phosphate (CaP) precursor phase is an important pathway for CFA precipitation. Moreover, the interface coupled dissolution and precipitation (ICDP) mechanism of CaP on calcium carbonate surfaces reveals the alteration genesis of CFA from a microscopic perspective. Based on these findings, future research directions for investigating the genesis of authigenic CFA in marine sediments are also proposed.

     

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