TRACE ELEMENTS IN QUARTZ: INSIGHTS INTO SOURCE AND FLUID EVOLUTION IN MAGMATIC-HYDROTHERMAL SYSTEMS

Abstract

AbstractQuartz trace elements record information about fluid evolution as well as metal migration and precipitation. Here, we summarize most of the reported (including this study) quartz trace element data (N = ~4,600) generated by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) on various textural types and paragenetic stages of quartz in I-type porphyry-epithermal (Cu-Mo-Au-Ag-Te) and S- and A-type granitegreisen (Sn-W and rare metal) systems in the world. The results show that Li versus Al diagrams, combined with Ti-Ge-As-Sb contents, can be used to decipher the source and evolution of fluids in magmatic-hydrothermal systems. In I-type porphyry-epithermal systems, magmatic quartz has low Li/Al ratios from 0.001 to 0.173 (N = 483) with a mean of 0.039 ± 0.032. Hydrothermal quartz has progressively higher Li and Al concentrations that are dominated by cooling along fluid pathways. Quartz evolves from Ti rich to Ge rich from early to late stages in porphyry hydrothermal veins and is As and Sb rich in epithermal veins. In S- and A-type granite-greisen systems, magmatic quartz has high Li/Al ratios from 0.007 to 0.502 (N = 604) with a mean of 0.130 ± 0.063 and from 0.009 to 0.327 (N = 325) with a mean of 0.126 ± 0.065, respectively. Hydrothermal quartz has progressively lower Li and Al concentrations that are dominated by fluid-rock reactions and cooling along fluid pathways. Quartz evolves with decreasing Ti concentrations from magmatic to hydrothermal stages. Ge is abundant in pegmatite quartz in S-type systems. Variations in pH or precipitation rate along fluid pathways have a small influence on Li/Al ratios. The variation of quartz trace elements with elevation in individual systems suggests that they can be used as a vector to guide exploration in magmatic-hydrothermal systems.