Radiometric Dating Applied to Ore Deposits: Theory and Methods

Abstract

Metallic ore deposits have contributed to the development of the human society since pre-historic times and nowadays are one of the pillars of unprecedented technological developments. In order to understand how metallic ore deposits form and thus construct genetic models that may serve as exploration guides, determining the age of an ore deposit is one of the most important pieces of information needed. More recently it has also become evident that determining the temporal duration of mineralizing events can offer valuable information on how certain deposits form and thus improve genetic models. Radiometric dating of ore minerals or of other minerals that are demonstrably associated in space and time with mineralization is the most accurate and precise tool to date an ore deposit. This Introductory Chapter summarizes basic concepts on why ore deposit dating is important and how this can be achieved through different methods. It illustrates basic differences among different methods and serves as an introduction to the more detailed descriptions of specific dating methods presented in the following Chapters.

Cenozoic Pb–Zn–Ag mineralization in the Western Alps

“…Another advantage of cross-comparison of Rb-Sr and U-Th-Pb dating paired in thin section is the ability to distinguish different crystallization stages (Chiaradia, 2023). The primary Eocene mineralization of the Le Gros Villan deposit (37.1 ± 0.7 Ma, monazite) contains secondary phengite (Ph2) and galena (Gn2) in post-mineralization microstructures (localized foliation and fractures, Fig.…”

“…However, less-common Pb-Zn-Ag deposits may have an extended evolution influenced by orogenic processes (Williams, 1998) that redistributed the ore minerals (Cugerone et al, 2021). Extracting the ages of crystallization and subsequent remobilization of polymetallic ore deposits has proven challenging due to potential reopening of the isotopic systems (Chiaradia, 2023). Dating actinide-rich accessory minerals is the most common and reliable method for obtaining accurate ages because of the possibility to check for concordance using the triple U-Th-Pb decay series (Rasmussen et al, 2006;Li et al, 2019).…”