Extraction of soils above concealed lithium deposits for rare metal exploration in Jiajika area: A pilot study

Jiajika in Sichuan, China, is an important mining area for lithium and other Group I and Group II elements. However, the weathered residual overburden makes it difficult to prospect using traditional soil geochemistry. Deep-penetrating geochemical theories provide new ideas and methods that can be used to explore for concealed ore bodies. In this study, topsoil samples were collected from 10 to 25 cm depth above two concealed lithium deposits, Vein 804 (V-804) and Vein X03 (V-X03). Lithium (Li), cesium (Cs), rubidium (Rb), beryllium (Be), and boron (B) were extracted from the soils using pure water and 0.2 mol/L potassium sulfate solutions (K2SO4). Anomalies were observed for water-extractable Li, Cs, and Rb, and K2SO4-extractable Li, Cs, and Be in samples from above both veins. The harmonic mean of the data for each element was used to calculate the response ratio. The highest response ratios are 1.2-2.5 times and 2 to 8 times higher than the response ratios for other samples from V-804 and V-X03, respectively. Linear correlations are observed between the water-extractable and K2SO4 extractable elements, and imply that unbound species of the elements were extracted by K2SO4. The extracted elements display single peak, double peak, and multi-peak anomaly patterns, which indicate that transfer of Li, Cs, Rb, Be, and B through the overburden may be through a combination of diffusion, capillarity, electrochemical forces, and redox gradients.