Pathfinder elements are trace elements related to the target mineral, and which occur more widespread or can be detected in larger amounts compared to the targeted element or primary commodity. During regional exploration programs, these elements create geochemical haloes, indicating the presence of deeper-seated concealed mineralization, which would be unknown in the absence of such elements (Orlandea & Vlad, 2020).
Carlin-type gold deposits are distinctive types of sediment-hosted gold deposits, where microscopic gold is enclosed inside iron sulfide minerals like arsenian pyrite. Due to the submicroscopic nature of the gold and its general low-grade association with bulk rock, depending only on the gold assays during preliminary regional explorations would be quite ineffective and thus the identification of certain pathfinder elements would be crucial (Wang et al., 2024).
Some of the most important primary geochemical prospecting tools in Carlin-style systems are arsenic (As) and antimony (Sb). Being elements of a volatile nature, As and Sb easily mobilize within low-temperature hydrothermal fluids and form significant deposits in the host sedimentary rocks. Relatively high mobility allows these elements to form large geochemical haloes, which are easy to collect from stream sediments, soil samples, and even surface rocks (Wang et al., 2024).
Other geochemical elements that are highly indicative in identifying sediment-hosted gold systems include mercury (Hg) and thallium (Tl). Thallium, for instance, is characterized by unusual element distribution in sediment-hosted gold systems. According to the analysis of geochemistry, Tl reveals distinctive elemental and isotopic signatures due to the presence of low-temperature hydrothermal fluid migration along regional faults and breccias (Fitzpayne et al., 2018).
During the reconnaissance period’s active phase, scientists use advanced multi-element factor analysis to interpret the spatial patterns of these pathfinders. Through the plotting of overlapping concentration anomalies for all four As-Sb-Hg-Tl elements together, exploratory programs will be able to distinguish between genuine mineralization and typical regional background variability. The use of a multi-element approach is necessary to avoid misinterpreting barren variations in the lithology (Wang et al., 2024).
At last, the geochemical exploration of As, Sb, Hg, and Tl elements prove essential in the detection of concealed Carlin-type ore deposits. In following the traces of past hydrothermal activity, modern geoscientists have a unique ability to locate the widespread elemental anomalies and get straight to the micro-level gold core of such sedimentary deposits.
References
Fitzpayne, A., Prytulak, J., Wilkinson, J. J., Cooke, D. R., Baker, M. J., & Wilkinson, C. C. (2018). Assessing thallium elemental systematics and isotope ratio variations in porphyry ore systems: A case study of the Bingham Canyon district. Minerals, 8(12), 548. https://doi.org/10.3390/min8120548
Orlandea, E., & Vlad, Ş.-N. (2020). A novel conceptual model of intrusion related gold bearing systems and exploration tools. Studia Universitatis Babes-Bolyai, Geologia, 63(1), 1-12. https://doi.org/10.5038/1937-8602.63.1.1304
Wang, X., Cao, S., Tan, Q., Xie, Z., Xia, Y., Zheng, L., Liu, J., Zhou, K., Xiao, J., & Ren, T. (2024). Exploration vectors and indicators extracted by factor analysis and association rule algorithms at the Lintan Carlin-type gold deposit, Youjiang Basin, China. Minerals, 14(5), 492. https://doi.org/10.3390/min14050492
