江西朝阳磷块岩物理富集成矿

本文研究了江西朝阳磷块岩物理富集成矿的各种沉积标志,划分了两个不同的物理富集作用类型。海平面的振荡升降导致矿源层的形成和破坏,当沉淀作用和冲刷再沉积作用达到最佳配合时,层厚质优的工业矿层得以形成。造海运动是工业磷块岩物理富集成矿的最根本条件。

PHYSICAL ENRICHMENT OF PHOSPHATE IN ZHAOYANG PHOSPHORITE DEPOSIT, JIANGXI PROVINCE

The ore bed of Zhaoyang phosphorite deposit occurs in the late Sinian Doushantuo Formation. It consists of 3 mineralized horizons, but only one of which is productive.The sedimentological marks for physical enrichment are striking. For example, the productive ore bed is always composed of grain phosphorite, the phosphate grains are mostly iutraclasts of phosphorite, the erosion surfaces or strata-bound discontinuities in ore bed are developed, the grain-sequence bedding and rhythm in the ore bed are well developed, the ore is well sorted, and the correlation between grain-size and thickness of ore bed is positive. All these characteristics of phosphorite indicate that the ore bed was generated in a shallow water environment with high energy.P2O5 content in grain phosphorite is more than that in non-grain phosphorite. The more phosphate grains of ore bed, the more P2O5 content in phosphorite, and the larger thickness of the ore bed.Physical enrichment may be of two types, i. e. winnowing residual-sedimentation and the transport-sorting. They are different from each other in the characteristics of texture and granulity, and relations between kurtosis and deviation, and between deviation and median value.The source ore bed was formed and reworked by the pulsation and oscillation of sea level. During the best combination of sedimentation and erosion-resedimentation, the productive ore bed is formed. Thus, the eustatic movement is the basic condition for physical enrichment of the productive phosphorite.