海相磷块岩沉积事件研究——以新元古代末—寒武纪成磷事件为例

MARINE PHOSPHORITE SEDIMENTATION EVENT:A CASE STUDY OF PHOSPHORITE-FORMING EVENT FROM THE END OF NEOPROTEROZOIC TO CAMBRIAN

磷块岩大规模沉积是古海洋磷循环作用的结果。为解释海相磷块岩成因,提出了各种理论。大规模成磷事件的发生与古海洋条件和古生态环境有关,从C—N—P—O等元素循环来探讨成磷现象成为目前的趋势。磷也是重要的生命元素,磷酸盐的富集与生物演化之间也存在一定的联系。新元古代末—寒武纪磷块岩沉积是第1次全球性大规模成磷事件,它与Rodinia超大陆解体、新元古代晚期冰川事件的结束、古海洋水体地球化学条件的变化及新旧生态系统更迭等因素有关,而成磷事件又对这一时期的生物演化与生命创新事件起到了促进作用。对磷块岩的成因理论、古海洋磷循环等进行了分析,并从新元古代末—寒武纪磷块岩沉积的时空分布和成磷事件对生物演化的影响方面进行了探讨。

Large-scale sedimentation of phosphorite in ocean is a result from P cycle in the ancient ocean. People advanced many genetic theories to explain multiple phosphorite-forming events that occurred in geologic histo- ry. Large-scale phosphorite formations were closely related to paleo-oceanic conditions and paleo-ecologic envi- ronments, and now it has become a tendency to study phosphorite formation from C-N-P-O element cycle process. Since P is an important life element, phosphate enrichment has some relations with biologic evolu- tions. End of Neoproterozoic-Cambrian phosphorite sedimentation was the first large-scale global P-forming e- vent, and had something to do with Rodinia Pangea break-up, the end of glacial event during the late time of Neoproterozoic, severe changes in geochemical conditions of paleo-oceanic water mass, and alternations o{ old and new ecologic systems during transition periods. And P-forming event promoted biologic evolution and life innovation events of such times. The authors analyzed the phosphorite formation event in the aspects of genesis theories, paleo-oeeanic P cycles, time-space distribution of end of Neoproterozoic-Cambrian phosphorite sedi- mentation and the impact on biologic evolution.