Genesis of Giant Shitouping Heavy Rare Earth Element Deposit,in Southern Jiangxi Province:Constraints from Mineralogy and Geochemistry of Regolith
Yang Wanzhen
He Chuan
Wang Yun
Li Mangen
Wang Xianguang
Chen Qiru
Gong Liangxin
Zhong Wen
Abstract：Rare earth elements(REE)are strategic metals worldwide.Regolith-hosted heavy rare earth element(HREE)deposits are the world's main HREE producer,and their genesis is widely debated.The Shitouping HREE deposit is a newly discovered giant regolith-hosted HREE deposit in Ganzhou,Jiangxi,and its genesis is still unclear.Therefore,it carried out systematic sampling within a weathered crust profile from top to bottom using the Gannan drill,and revealed the mineralogy,elemental geochemistry,and pH characteristics of the profile using the X-ray diffraction,scanning electron microscopy,X-ray fluorescence spectroscopy,and inductively coupled plasma mass spectrometry.The results show that the species and morphology of clay minerals in the regolith profile exhibit zonality.Topsoil layer and upper completely weathered zone are mainly composed of highly crystalline kaolinite,while lower completely weathered zone and semi-weathered zone are mainly composed of short-tubular halloysite and low-crystalline kaolinite,reflecting the transformation process of clay mineral crystallinity from low to high in the regolith profile from bottom to top.The zonality of clay minerals leads to differences in adsorption capacity which controls the transformation of REE's adsorption-desorption behavior.The enrichment feature of REE shows increasing followed by decreasing from top to bottom,their shape resembles as a"bow".The differentiation characteristics of REE present as light rare earth elements(LREE)accumlating in upper regolith and HREE gathering in lower regolith(upper LREE-lower HREE).The enrichment characteristics of the REE have a significant correlation with the weathering degree at different weathering stages.When the weathering intensity is less than 85,there is a positive correlation between weathering intensity and the quantities of the REE,whereas the weathering intensity is greater than 85,there is a negative correlation.The upper LREE-lower HREE differentiation characteristic is closely related to the variations on pH values and clay minerals'species and morphology in regolith.The pH values in the profile gradually increase from top to bottom,and the mobilization ability of the REE ions gradually decreases.The HREE ions with relatively higher downward migration rates are more prone to accumulate in the lower regolith,and the HREE ions are preferentially adsorbed under high pH conditions.Therefore,the genesis of Shitouping HREE deposit is controlled by the mineralogy and structural characteristics of the regolith.
Keywords：Shitouping HREE depositgranitic regolithclay mineralregolith-hosted REEin southern Jiangxi Provincemineral depositsgeochemisty
Publication Date：2025-04-30
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：18( 1335-1352 )