Gallium- and germanium-rich sphalerite in the Sichuan-Yunnan-Guizhou region: Insights from the Fule carbonate-hosted Pb-Zn deposit

Abstract

The Sichuan-Yunnan-Guizhou (SYG) region hosts significant resources of critical metals gallium (Ga) and germanium (Ge), which are essential to the development of green technologies. The content and distribution of Ga and Ge in sphalerite from the carbonate-hosted Pb-Zn Fule deposit in this region need to be evaluated. Based on laser ablation-inductively coupled plasma-mass spectrometry analysis, we investigate Ga, Ge, and other minor and trace element composition in different types of sphalerite from this deposit. Two major mineralization stages (I and II) were recognized in hydrothermal period. The highest Ga (mean 218 ppm) and Ge (mean 760 ppm) contents were both found in reddish-brown sphalerite (Sp1rb) formed in stage I. Varicolored sphalerite (Sp2) deposited in stage II and white sphalerite (Sp1w) formed in stage I exhibit the lowest Ga (mean 0.25 ppm) and Ge (mean 13.2 ppm) contents, respectively. Trace element content correlations reveal Ga incorporation via direct substitution and Ge incorporation via substitution coupled to monovalent copper ion. Additionally, the sphalerite color variations (reddish-brown, yellow, and white) at Fule are related to the contents of Cu, Ga, Ge, As, and Sb. Compared to sphalerite in the other typical Pb-Zn deposits in the SYG region, sphalerite from the Fule deposit is more enriched in Ga and Ge. Considering the close spatial relationship between the Fule deposit and the Emeishan basalts, we propose that the Emeishan basalts may have contributed additional Ga and Ge to this deposit.