Extreme enrichment of rare earth elements in hard clay rocks and its potential as a resource

摘要: Abstract The Xuanwei Formation is widely distributed in western Guizhou Province, NW China, the lower section of which primarily composed gray-white kaolinitic claystone interbedded with thin layers grayish black carbonaceous mudstone that are extremely enriched rare earth elements. In order to determine distribution patterns and existing status ore-forming elements these rocks, careful field investigations were performed along a selected geological profile rock samples collected studied terms mineralogical geochemical characteristics. results show that: 1) REEs white clay sediments mudstone. Mineralogical analyses revealed kaolinite as major mineral rocks smaller amounts smectite, illite, boehmite, hornblende, pyrophyllite, calcite, dolomite and/or iron-bearing minerals, well certain proportion feldspar, quartz crystal debris non-crystal debris. 2) ∑ REE contents 89.0 9965 ppm an average 1312 ppm. thickness host higher than 1300 ppm more 4 m, referred “REE-enriched layer”. 3) REE bulk exhibit negative correlation kaolinite, positive correlations hornblende weak illite indicating might exist ion adsorption state space between minerals. 4) Compared underlying Emeishan Basalts, quite similar but both LREE HREE. degree enrichment HREE relatively high. Based on results, model suggested where REE-enriched originated from Basalts controlled by transportation deposition detritus paleo-weathering crust. hard have significant resource potential, REE, Ga, Nb Zr considerably those weathering crust type deposit.