Antimony in quartz as a vector to mineralization: A statistical approach from five Variscan Sb occurrences (France)

Abstract

Using in-situ LA-ICP-MS, the trace-element composition of hydrothermal quartz from five Sb mineralized Variscan districts, from different parts of France, were compared. Each of these districts is characterized by the presence of stibnite, with quartz being a ubiquitous gangue mineral. The resulting dataset was processed using a set of multivariate statistical analyses (i.e. principal component analysis, hierarchical cluster analysis, and permutational multivariate analysis of variance). This approach highlights differences in ore-forming processes (e.g., fluid chemistry), recorded in the trace-element pattern of gangue minerals. Using this methodology, we could distinguish different mineralizing events with intricate paragenesis, such as those in the Sioule nappe, which appear to have recorded two different events of Sb precipitation. Results indicate that Sb incorporation in quartz is weakly correlated to other trace elements, but that its contents increase sharply in quartz from stibnite-bearing veins. In this case, Sb shows values >10 ppm and up to 200 ppm, considerably higher than the values measured in quartz unrelated to Sb mineralization (mainly ≤1 ppm). Intermediate Sb contents in quartz would point to the potential for a fluid to precipitate Sb ore. It is concluded that incorporation of Sb in quartz can be confidentially correlated to its content in the mineralizing fluid. Based on our data from five Sb districts in the French Variscan belt, supplemented by published Sb trace-element data in quartz from a number of other Sb deposits around the world, this study highlights the strong potential of the Sb content of quartz as a proxy for tracing Sb mineralization.