A new palaeo-weathering and leaching model for the formation of the ultra-large high-grade Kaiyang phosphate deposit, Guizhou, China

• Published in: Arabian journal of geosciences Vol. 14; no. 22
• Main Authors: Wu, Wenming, Yang, Ruidong, Wang, Zepeng, Liu, Jianzhong, Wang, Dafu, Liu, Song, Yang, Chenfu, Ye, Taiping
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.11.2021; Springer Nature B.V
• Subjects: Aluminum oxide; Cements; Earth and Environmental Science; Earth science; Earth Sciences; Electron probe; Electron probe microanalysis; Isotopes; Lamination; Leaching; Original Paper; Phosphate deposits; Phosphates; Phosphorite; Phosphorus pentoxide; Rocks; Silica; Silicon dioxide; Sulfur trioxide; Weathering; China; Guizhou; Palaeo-weathering crust; Phosphorite; Kaiyang phosphate mine
• ISSN: 1866-7511; 1866-7538
• DOI: 10.1007/s12517-021-08587-x

The processes that formed the ultra-large and high-grade Kaiyang phosphate deposit, which is located in Guizhou Province, China, remain unclear. Here, we present the results of a petrological and mineralogical investigation of the compact and white lamination-bearing phosphorite within the deposit. These white lamination-bearing phosphorites contain many silicified collophane breccias that are surrounded by collophane cements. Electron probe microanalysis indicates that the phosphorite within the deposit is enriched in P 2 O 5 , SiO 2 , K 2 O, and Al 2 O 3 and is depleted in FeO, F, MgO, SO 3 , and Na 2 O compared with the more common clastic phosphorite rocks. In addition, the coated-grain phosphorite located beneath this layer contains a cement that was gravitationally transported and was formed by leaching. These new data indicate that the deposit represents a crust formed as a result of palaeo-weathering. The widespread presence of this type of phosphatic rock in the Kaiyang area indicates that palaeo-weathering played a key role in the formation of the phosphorite deposits in this region.