Laser ablation-ICPMS analysis of trace elements in pyrite from the Tharsis massive sulphide deposit, Iberian Pyrite Belt (Spain)

Abstract

High sensitivity laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) has been utilized for the determination of trace elements in pyrite from the Tharsis VMS deposit, one of the most significant volcanogenic massive sulphide deposits in the southern Iberian Pyrite Belt. The study tracks the content and distribution of trace elements within the different facies of massive sulphides. Widespread and variable enrichment in elements such as Cu, Zn, and Pb in pyrite is interpreted to be due to the presence of nanoinclusions of chalcopyrite, sphalerite, and galena, respectively. A second group of elements, including As, Au, Tl, Mn and Mo, shows significant chemical variations according to the type of mineralization and the textural evolution of the pyrite. This behaviour is thought to be due to the fact that these metals are included in the mineral lattice and its incorporation is controlled by the degree of crystallinity, the temperature, and the redox conditions during crystallization. Early, spongiform and colloform pyrite in the stockwork is enriched in As and Au and interpreted to have formed from a high temperature and low fS2–fO2 fluid. Thallium, Mn, and Mo are enriched in pyrite precipitated at lower temperature and higher oxidation state, i.e., in the exhalative part of the system or in distal facies to the hydrothermal vents. In general, both Co and Ni show an irregular distribution and do not have the sympathetic distribution observed in equivalent studies.