云南-贵州寒武系成磷期特征对比

Sediment Characteristics of the Lower Cambrian Phosphorus Rock and Comparison of Mineral Phase in Guizhou and Yunnan Provinces

贵州、云南寒武系底部磷块岩发育,是我国主要的含磷层位。然而,两个地区之间磷块岩沉积特征及成磷期次缺少对比,制约了云贵地区寒武系磷块岩的成磷规律的研究。为此,在对云南宁华、会泽和贵州织金磷块岩沉积特征对比的基础上,分析了寒武系磷块岩的沉积序列、成磷期次,提出富磷层位往往发育在海侵序列的晚期;而在海侵早期,虽然有大量的磷质供给,但由于同时供给的硅质、泥质也丰富,环境变化强烈,往往沉积纹层状、条带状磷块岩,其磷块岩品位低。海侵晚期,海岸环境相对稳定,又有大量磷质供给,高能环境对含磷沉积不断改造,磷质进一步富集,形成富磷的碎屑状磷块岩。因此,古地理位置、海侵序列发育对磷块岩具有重要的控制作用。根据扬子区古地理、织金地区含磷岩系厚度变化规律、沉积层序特征,认为贵州盘县-水城地区和织金-金沙地区是磷矿远景区。

The lower cambrian abundant phosphorus resource occurs in Guizhou and Yunnan Provinces.Guizhou and Yunnan Province＇s phosphorus rock is lack in research on comparison of mineral phase and sediment sequence,therefore,the relationship between Guizhou and Yunnan phosphorus rock is lack,mineral research of phosphorus deposit in the Upper Yangtze area is restrict. The sediment characteristics,sequence and mineral phase of the lower cambrian phosphorus rock were studied at Ninghua and Huize,Yunnan and Zhijin,Guizhou. The result shows that abundant phosphorus horizon occurs generally at upper transgression sequence,the content of P_2O_5 is high. Silious phosphorite and dolomite phosphorite with lamellar and vein occurs at the lower transgression sequence,the content of P_2O_5 is low. Dolomite occur at the HST,it is lack in phosphorus rock. ＂Ocean current rising＂concept suggests that the Ocean current rising is rich in P_2O_5,it difficult to form abundant phosphorus horizon under high sediment rate and unstable palaeogeographic environment during early transgression stage. But it easy to deposit abundant phosphorus horizon under supplement of abundant P_2O_5 water and stable palaeogeographic environment during late transgression stage. Palaeogeographic environment and transgression sequence were considered as main factor of mineral phosphorus deposit. Panxian-Shuicheng and Zhijin-Jinsha prospect area for phosphorus deposit in Guizhou Province are suggested on the basis of the characteristics of sedimentary sequence variation,the thickness of phosphate rocks and palaeogeographic environment.