滇东下寒武统生物磷块岩的形成机制

显微结构研究表明,广泛分布于滇东地区下寒武统的磷块岩,除少量生物介壳磷块岩外,其它类型的磷块岩(包括菌藻生物磷块岩、内碎屑磷块岩和次生(风化)磷块岩等的颗粒均由磷质菌藻生物组成。从而揭示了菌藻生物磷块岩是磷块岩的基本类型。本文重点论述了生物磷块岩的结构成因分类、时空展布规律,以及滇东磷块岩的菌藻生物成磷—富磷作用,并探讨了菌藻生物磷块岩的形成机制。

MECHANISM OF THE FORMATION OF LOWER CAMBRIAN BIOPHOSPHORITES IN EASTERN YUNNAN

Lower Chambrian phosphorites are classified into three genetic types:primary algalbacterial phosphorite, intraclastic phosphorite and secondary phosphorite in Eastern Yunnan. Achievements in microtexture research indicate,all grains of them consist phosphoric algae and bacteria except a few shell phosphorite. Thus,algal-bacterial phosphorites are main source of phosphorites.Discussion of this paper concentrate on classification of biophosphorites on the basis of the textures and geneses (phosphorites with algal-bacterial growing texture, phosphorite of the algalbacterial grain and shell phosphorite,their vertical and transverse distribution,and algal-bacterial bioaction of phospbatic formation and envichment as well as formational mechanism algal-bacterial phosphorites of Early Cambtian in Eastern Yunnan.