Changes in antimony isotopic composition as a tracer of hydrothermal fluid evolution at the Sb deposits in Pezinok (Slovakia)

Abstract

In this work, we investigated in situ isotopic compositions of antimony (Sb) minerals from two substages of the ore deposits near Pezinok (Slovakia). The δ123Sb values of the primary Sb minerals range from −0.4 and +0.8‰ and increase progressively along the precipitation sequence. In the substage II, the early-formed gudmundite (FeSbS) shows in all sections the lowest δ123Sb values, followed by berthierite (FeSb2S4), stibnite (Sb2S3), and valentinite (Sb2O3) with the heaviest δ123Sb values. A similar trend was observed for the substage III, from the initially-formed stibnite, followed by kermesite (Sb2S2O), valentinite, senarmontite (both Sb2O3), and schafarzikite (FeSb2O4). The evolution can be rationalized by a Rayleigh fractionation model with a starting δ123Sb value in the fluid of +0.3‰, applying the same mineral-fluid fractionation factor to all minerals. Thus, the texturally observed order of mineralization is confirmed by diminishing trace element contents and heavier δ123Sb values in successively crystallized Sb minerals. Antimony in substage III was likely supplied from the oxidative dissolution of stibnite that formed earlier during substage II. The data interpretation, although limited by the lack of reliable mineral-fluid fractionation factors, implies that Sb precipitation within each substage occurred from an episodic metal precipitation, likely associated with a similar Sb isotope fractionation between fluid and all investigated Sb minerals. Large isotopic variations, induced by precipitation from a fluid as a response to temperature decrease, may be an obstacle in deciphering the metal source in hydrothermal ore deposits. However, Sb isotopes appear to be an excellent instrument to enhance our understanding on how hydrothermal systems operate.

Determination Of Sb Isotope Ratios In Stibnite Using Fs-LA-MC-ICP-MS And Two Potential Reference Materials Study

“…Spectrosc. 2024, 45 (1), 33-43. methylation in biological processes, 8 adsorption processes, [9][10][11][12][13][14] evaporation and precipitation processes, 10,15 mixing processes, 16 and Rayleigh fractionation processes. 17 This characteristic makes Sb isotope composition a valuable tracer in the field of ore deposits.…”

“…17 This characteristic makes Sb isotope composition a valuable tracer in the field of ore deposits. 7,15,17,18 Recent research has revealed significant variations in Sb isotope ratios in Sb-bearing mineral deposits, with a maximum δ 123 Sb range exceeding 1‰. 6,7,15,17,19,20 As the geological database and fractionation theories of Sb isotopes continue to advance, the application prospects of Sb isotopes are poised to be extensive, offering valuable insights into redox changes in hydrothermal ore-forming systems.…”

“…7,15,17,18 Recent research has revealed significant variations in Sb isotope ratios in Sb-bearing mineral deposits, with a maximum δ 123 Sb range exceeding 1‰. 6,7,15,17,19,20 As the geological database and fractionation theories of Sb isotopes continue to advance, the application prospects of Sb isotopes are poised to be extensive, offering valuable insights into redox changes in hydrothermal ore-forming systems. Moreover, Sb isotopes play a crucial role in tracing metal sources, monitoring fluid evolution, studying ore-forming processes, and guiding mineral exploration.…”

Antimony Isotope Fractionation during Adsorption on Iron (Oxyhydr)oxides

“…24,27,46 Enhancing comprehension of the process of fractionation during adsorption can provide valuable insights into the utilization of isotope tracer approaches. 24,27,47 Iron (oxyhydr)oxides are common minerals in soils and sediments and exert significant effects on the (bio)geochemistry of metal pollutants. 48 Several studies have investigated the adsorption behavior of Sb absorbed on ferrihydrite, goethite, and hematite.…”

“…Prior research on nontraditional stable isotopes indicates adsorption is commonly recognized as a significant mechanism that often leads to stable isotope fractionation. − ,− The adsorption of Zn onto iron (oxyhydr)­oxides results in the enrichment of heavy isotopes yet iron (oxyhydr)­oxides prefer to absorb light Ni isotopes. , The fractionation magnitude can also vary for different iron (oxyhydr)­oxides. − The migration of Sb can be affected by the presence of Fe (oxyhydr)­oxides in both soil and aqueous environments . The affinity of Sb­(V) toward the iron oxides depends on Sb species, pH, and the characteristics of iron (oxyhydr)­oxides, and the bidentate mononuclear edge-sharing complex is involved in the adsorption process. , The process of heavy isotope enrichment in mine drainage water can be attributed to the adsorption of Sb­(OH) 6 – on Fe hydroxides. ,, Enhancing comprehension of the process of fractionation during adsorption can provide valuable insights into the utilization of isotope tracer approaches. ,, …”