Trace Elements in Magnetite from the Pagoni Rachi Porphyry Prospect, NE Greece: Implications for Ore Genesis and Exploration

Mavrogonatos C, Voudouris P, Berndt J, Klemme S, Zaccarini F, Spry P, Melfos V, Tarantola A, Keith M, Klemd R, Haase K

Research article (journal)

Abstract

Magnetite is a common accessory phase in various types of ore deposits. Its traceelement content has proven to have critical implications regarding petrogenesis and as guides in theexploration for ore deposits in general. In this study we use LA-ICP-MS (laser ablation-inductivelycoupled plasma-mass spectrometry) analyses of trace elements to chemically characterize magnetitefrom the Pagoni Rachi Cu–Mo–Re–Au porphyry-style prospect, Thrace, northern Greece. Igneousmagnetite mostly occurs as euhedral grains, which are commonly replaced by hematite in fresh topropylitic-altered granodiorite porphyry, whereas, hydrothermal magnetite forms narrow veinlets oris disseminated in sodic/potassic-calcic altered (albite + K-feldspar + actinolite + biotite + chlorite)granodiorite porphyry. Magnetite is commonly associated with chalcopyrite and pyrite and locallyexhibits martitization. Laser ablation ICP-MS analyses of hydrothermal magnetite yielded elevatedconcentrations in several trace elements (e.g., V, Pb,W, Mo, Ta, Zn, Cu, and Nb) whereas Ti, Cr, Ni,and Sn display higher concentration in its magmatic counterpart. A noteworthy enrichment in Mo,Pb, and Zn is an unusual feature of hydrothermal magnetite from Pagoni Rachi. High Si, Al, andCa values in a few analyses of hydrothermal magnetite imply the presence of submicroscopic ornano-inclusions (e.g., chlorite, and titanite). The trace element patterns of the hydrothermal magnetiteand especially the decrease in its Ti content reflect an evolution from the magmatic towards thehydrothermal conditions under decreasing temperatures, which is consistent with findings fromanalogous porphyry-style deposits elsewhere.

Details zur Publikation

Release year: 2019
Language in which the publication is written: English