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This chapter discusses how radiogenic and stable isotopes can be used in the study of metallic mineral deposits. Although the chapter is mostly focused on the radiogenic (Pb, Os) and heavy stable (Fe, Cu, Zn) isotopes of metallic elements, we complement the discussion highlighting also the power of stable isotopes of light elements, which are major to significant components of hydrothermal fluids and rocks (e.g., H, B, C, N, O, S), as well as of radiogenic isotopes of elements (Sr, Nd, Hf ) that are useful in tracing fluid/magma sources and their interaction with the host rocks. In the first part of this chapter we discuss general aspects of isotopes clarifying the differences between stable non-radiogenic and stable radiogenic isotopes and, consequently, their different applicability to metallogenic studies. Due to their properties, stable non-radiogenic isotopes record mass-dependent fractionation that occur in many reactions associated with the formation of mineral deposits. Mass-dependent fractionation of stable non-radiogenic isotopes occurs both under equilibrium and non-equilibrium (kinetic) conditions of the reactions leading to ore mineral deposition and is controlled by various physico-chemical parameters, like, among the principal ones, temperature, oxygen fugacity, and biological activity. Therefore, stable non-radiogenic isotopes can inform us about the physico-chemical and, eventually, biological processes that control ore mineral deposition and also on the sources of some metals (e.g., transition metal isotopes of elements like Fe, Cu, Zn) or of the fluids (e.g., H, C, O, N, S isotopes) and even of metal ligands (e.g., S, Cl). We conclude the first part of the chapter providing some hints on the strategy of sampling and on the instrumentation related to isotopic studies. In the second part we discuss radioactive-radiogenic isotope systems and their applications in metallogenic studies of metallic mineral deposits. Stable radiogenic isotopes are characterized by relative variations that are controlled, in each geological system, by the addition of a radiogenic component of an isotope, derived from the decay of a radioactive parent, to the same radiogenic isotope already present in the Earth since its formation  4.55 Gyr ago. This relative variation is usually expressed as the ratio of a radiogenic isotope of an element to a non-radiogenic isotope of the same element. The ratio of these two isotopes has increased since the Earth formation and the magnitude of its variations depends on the radioactive/ radiogenic isotope ratios in different geological systems and on the time elapsed since the system has formed. The Earth is  4.55 Gyr old and has evolved from an initially homogeneous isotopic composition to reservoirs (e.g., mantle, crust) and crustal rocks with very variable radioactive/radiogenic isotope ratios due to magmatic, metamorphic, weathering, atmospheric and biologic processes, among others. This has resulted in extremely large variations of radiogenic isotopes in rocks and reservoirs of the Earth which can track various geological processes. In ore geology, stable radiogenic isotopes are best suited for tracing metal (e.g., Pb, Os) sources from different rocks and reservoirs (e.g., mantle, upper crust, lower crust), fluid-rock interactions (i.e., the hydrothermal plumbing system), or magma-host rock interactions (e.g., host rock assimilation by magmas associated with magmatic-hydrothermal deposits). Radioactive-radiogenic isotope systems allow us to determine also absolute ages of suitable minerals that are found in mineral deposits. This is an essential information in metallogeny that allows us to link the formation of a mineral deposit to a specific geological process and/or to specific periods of the Earth’s history. We discuss various dating methods that are extensively applied to date mineral deposits. These methods can be subdivided into those that allow a direct dating of ore minerals (e.g., RedOs dating of molybdenite, UdPb dating of cassiterite) and those that allow dating of minerals that are demonstrably related with the mineralization (e.g., UdPb dating of zircon from magmatic rocks associated with magmatic-hydrothermal deposits; Ar/Ar dating of K-bearing minerals resulting from alteration associated with various types of mineral deposits). We discuss pros and cons of using these various methods and also mention methods that are less used (because potentially less accurate and precise), but sometimes represent the only possibility to provide an age to deposit types that are notoriously difficult to date (e.g., MVT and Carlin-type deposits). We highlight the power of both stable radiogenic and non-radiogenic isotopes in unravelling the genesis of metallic mineral deposits through a series of conceptual and real examples applied to a broad range of mineral deposit types such as porphyry systems (i.e., porphyry deposits, high- and intermediate-sulfidation epithermal deposits, skarn, carbonate replacement deposits, sediment-hosted Au deposits), low-sulfidation epithermal deposits, IOCG deposits, ortho-magmatic deposits, volcanic-hosted massive sulfide deposits (VHMS), sediment-hosted deposits (stratiform copper, MVT), and supergene deposits. In the third part of the chapter, we discuss the use of transition metal stable non-radiogenic isotopes to mineral deposits. Although in its infancy, the application of transition metal isotopes to mineral deposit investigation is quickly growing because these isotopes allow us to address different aspects of the formation of mineral deposits compared to radiogenic isotopes. In particular, isotopes of transition metals (like stable isotopes of light elements) undergo mass-dependent fractionation processes that may be associated with different types of equilibrium and non-equilibrium chemical, physical and biological reactions occurring during the formation of mineral deposits. We focus on the applications of the isotopes of Cu, Fe and Zn to various deposit types, because isotopes of these transition metals are those that have been most extensively used in mineral deposit studies. Mass-independent fractionation may also occur for isotopes of some elements and could be a developing field that has not yet been extensively explored in the study of mineral deposits. 

Abstract Stibnite is a relatively common mineral in epithermal deposits, with little known about Sb transport and efficient stibnite precipitation. The famous Kremnica Au-Ag low-sulfidation deposit and Zlatá Baňa intermediate-sulfidation Pb-Zn-Cu-Au-Ag-Sb deposit are hosted in two different Neogene volcanic fields in Western Carpathians, Slovakia. In both deposits, stibnite-rich veins occur outside of major vein structures, accompanied by illite, illite/smectite, and kaolinite alteration, and affiliated to late-stage fluids (< 2 wt% NaCl eq., < 150 °C). Sulfur isotopic composition of stibnite and sulfides is different at both deposits, likely due to a different magmatic-hydrothermal evolution of the parental magmatic chambers in the Central and Eastern Slovak Volcanic Fields. The Sb isotopes (δ¹²³Sb), however, show similar values and trends of gradual simultaneous increase with δ³⁴S values, explained by a progressive precipitation of stibnite and its fractionation with the fluid. The data were modeled by two coupled Rayleigh fractionation models, (for Sb and for S), assuming a predominant Sb transport in HSb₂S₄^–with a variable amount of S species. Higher molality ratio m_S/m_Sbof fluids was found in Kremnica (~ 3–4) than in Zlatá Baňa (~ 2). At both deposits, the heaviest δ¹²³Sb values are accompanied by a decrease in the δ³⁴S values probably due to the commencement of pyrite/marcasite precipitation. According to thermodynamic models of solubility of Sb(III) complexes and observations from active geothermal fields, stibnite precipitation was triggered by temperature decrease accompanied by mixing with a mildly acidic fluid (pH 4–5) of a steam-heated CO₂-rich condensate on margins and in the final stages of epithermal systems. The proposed model for the origin of stibnite-bearing veins in epithermal systems can be used for their better targeting and efficient mineral exploration. 

Published Sn isotope data along with 150 new analyses of cassiterite and four granite analyses constrain two major tin isotope fractionation steps associated with (1) separation of tin from the magma/orthomagmatic transitional environment and (2) hydrothermal activity. A distinct Sn isotope difference across deposit type, geological host rocks, and time of ore deposit formation demonstrates that the difference in the mean δ124Sn value represents the operation of a unified process. The lower Sn isotope values present in both residual igneous rocks and pegmatite suggest that heavier Sn isotopes were extracted from the system during orthomagmatic fluid separation, likely by F ligands with Sn. Rayleigh distillation models this first F ligand-induced fractionation. The subsequent development of the hydrothermal system is characterized by heavier Sn isotope composition proximal to the intrusion, which persists in spite of Sn isotope fractionating towards isotopically lighter Sn during hydrothermal evolution. 

Ti-isotope fractionation on the most Ti-rich minerals on Earth has not been reported. Therefore, we present a chemical preparation and separation technique for Ti-rich minerals for mineralogic, petrologic, and economic geologic studies. A two-stage ion-exchange column procedure modified from the previous literature is used in the current study to separate Ti from Fe-rich samples, while α-TiO2 does not require chemical separation. Purified solutions in conjunction with solution standards were measured on two different instruments with dry plasma and medium-resolution mode providing mass-dependent results with the lowest errors. 49/47TiOL-Ti for the solution and solids analyzed here demonstrate a range of >5‰ far greater than the whole procedural 1 error of 0.10‰ for a synthetic compound and 0.07‰ for the mineral magnetite; thus, the procedure produces results is resolvable within the current range of measured Ti-isotope fractionation in these minerals. 

Abstract Numerous geochemical anomalies exist at the K-Pg boundary that indicate the addition of extraterrestrial materials; however, none fingerprint volatilization, a key process that occurs during large bolide impacts. Stable Zn isotopes are an exceptional indicator of volatility-related processes, where partial vaporization of Zn leaves the residuum enriched in its heavy isotopes. Here, we present Zn isotope data for sedimentary rock layers of the K-Pg boundary, which display heavier Zn isotope compositions and lower Zn concentrations relative to surrounding sedimentary rocks, the carbonate platform at the impact site, and most carbonaceous chondrites. Neither volcanic events nor secondary alteration during weathering and diagenesis can explain the Zn concentration and isotope signatures present. The systematically higher Zn isotope values within the boundary layer sediments provide an isotopic fingerprint of partially evaporated material within the K-Pg boundary layer, thus earmarking Zn volatilization during impact and subsequent ejecta transport associated with an impact at the K-Pg. 

Abstract The lower crustal domain of the Ivrea‐Verbano Zone (NW Italy) hosts five ~300‐m‐wide pipe‐like ultramafic intrusions that are metasomatized and exhibit Ni‐Cu‐PGE sulphide mineralization. To better constrain the role of metasomatism in the ore genesis, we studied the best‐preserved pipe at Valmaggia which was emplaced 249 Myrs ago. Phlogopite⁴⁰Ar/³⁹Ar analyses show that the pipe was infiltrated by metasomatic fluids derived from the subcontinental lithospheric mantle (SCLM) in two pulses at ~208 Ma and ~189 Ma which introduced sulphides into the pipe. Consequently, the pipe repeatedly acted as a preferred path for mass transfer from the SCLM into the lower crust over >60 Myrs (i.e., emplacement to second metasomatic pulse). Uplifted block margins, such as the Ivrea‐Verbano Zone, are potentially important exploration targets for magmatic sulphides. We argue that exploration strategies should focus on structures such as pipes that can focus metasomatic agents during ascent through the lithosphere.