Abstract
Abstract. We investigate the occurrence and chemistry of magmatic sulfides and their chalcophile metal cargo behaviour during the evolution of compositionally different magmas from diverse geodynamic settings both in mineralised and barren systems. The investigated areas are the following: (a) the Miocene Konya magmatic province (hosting the Doğanbey Cu–Mo porphyry and Inlice Au epithermal deposits, representing post-subduction) and (b) the Miocene Usak basin (Elmadag, Itecektepe, and Beydagi volcanoes, the latter associated with the Kişladağ Au porphyry in western Turkey, representing post-subduction). For comparison we also investigate (c) the barren intraplate Plio-Quaternary Kula volcanic field west of Usak. Finally, we discuss and compare all the above areas with the already studied (d) Quaternary Ecuadorian volcanic arc (host to the Miocene Llurimagua Cu–Mo and Cascabel Cu–Au porphyry deposits, representing subduction). The volcanism of the newly studied areas ranges from basalts to andesites–dacites and from high-K calc-alkaline to shoshonitic series. Multiphase magmatic sulfides occur in different amounts in rocks of all investigated areas, and, based on textural and compositional differences, they can be classified into different types according to their crystallisation at different stages of magma evolution (early versus late saturation). Our results suggest that independently of the magma composition, geodynamic setting, and association with an ore deposit, sulfide saturation occurred in all investigated magmatic systems. Those systems present similar initial metal contents of the magmas. However, not all studied areas present all sulfide types, and the sulfide composition depends on the nature of the host mineral. A decrease in the sulfide Ni∕Cu (a proxy for the monosulfide solid solution (mss) to intermediate solid solution (iss) ratio) is noted with magmatic evolution. At an early stage, Ni-richer, Cu-poorer sulfides are hosted by early crystallising minerals, e.g. olivine–pyroxene, whereas, at a later stage, Cu-rich sulfides are hosted by magnetite. The most common sulfide type in the early saturation stage is composed of a Cu-poor, Ni-rich (pyrrhotite mss) phase and one to two Cu-rich (cubanite, chalcopyrite iss) phases, making up ∼84 and ∼16 area % of the sulfide, respectively. Sulfides resulting from the late stage, consisting of Cu-rich phases (chalcopyrite, bornite, digenite iss), are hosted exclusively by magnetite and are found only in evolved rocks (andesites and dacites) of magmatic provinces associated with porphyry Cu (Konya and Ecuador) and porphyry Au (Beydagi) deposits.
Highlights
Petrographic and mineral chemistry studies of magmatic sulfides have been carried out on magmatic sulfides associated with orthomagmatic Ni–Cu–PGEmineralised systems (PGE – platinum-group elements; e.g. Barnes et al, 2017; Mungall and Brenan, 2014)
In order to investigate the magmatic sulfide occurrence in volcanic rocks characterised by a post-subduction geodynamic setting, we focus our study on three volcanic areas located in western Anatolia (Turkey), namely the Konya volcanic belt, the Usak basin (Elmadag, Itecektepe, and Beydagi volcanoes), and the Kula volcanic field (Fig. 2)
The volcanic rocks of the studied areas display a wide range of SiO2 and alkali element concentrations ranging from basalts to andesites–dacites with high-K calc-alkaline to shoshonitic affinity (Fig. 3a, b)
Summary
Petrographic and mineral chemistry studies of magmatic sulfides have been carried out on magmatic sulfides associated with orthomagmatic Ni–Cu–PGEmineralised systems (PGE – platinum-group elements; e.g. Barnes et al, 2017; Mungall and Brenan, 2014). Nadeau et al, 2010; Park et al, 2015; Fulignati et al, 2018; Zelenski et al, 2017; Keith et al, 2017; Savelyev et al, 2018) in order to track processes affecting the fertility of these systems. It is still unclear how sulfide saturation affects the process of magmatic–hydrothermal ore formation. Chiaradia: Magmatic sulfides in volcanic rocks and metal-rich cumulates may represent a temporary storage, which subsequently releases chalcophile metals to the magmatic hydrothermal system (e.g. Nadeau et al, 2010; Wilkinson, 2013; Fontboté et al, 2017)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
