Quartz chemistry – A step to understanding magmatic-hydrothermal processes in ore-bearing granites: Cínovec/Zinnwald Sn-W-Li deposit, Central Europe

摘要

Graphical abstractDisplay OmittedHighlights?For the first time, quartz from a 1.6?km deep section of granite pluton is studied.?Magmatic quartz evolved from Al-poor and Ti-rich to Al-rich and Ti-poor.?Hydrothermal quartz is distinguished by low contents of both Al and Ti.?Very late hydrothermal quartz is enriched in Al, Li, Rb and Sr.AbstractQuartz from granites, greisens and quartz veins from a 1596?m long vertical section through the Cínovec/Zinnwald Li-Sn-W deposit (Czech Republic) was studied using cathodoluminescence (CL) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP MS). The trace contents of Al, Ti, Li and the Ge/Ti and Al/Ti values in quartz reflect the degree of fractionation of parental melt from which primary quartz crystallized. From the biotite granite to the younger zinnwaldite granite, quartz is characterized by increasing contents of Al (from 136–176 to 240–280?ppm) and decreasing Ti (from 16–54 to 6–14?ppm), while the contents of Li and Ge are similar (15–36 and 0.8–1.7?ppm, respectively). Quartz of the greisen stage and vein stage is poor in all measured elements (26–59?ppm Al, 0.5–1.6?ppm Ti, 2–13?ppm Li, 0.8–1.6?ppm Ge). The youngest low-temperature quartz forming thin coatings in vugs in greisen and veins differs in its extreme enrichment in Al (>1000?ppm) and Li (?100?ppm) and very low Ti (<1?ppm). Within the greisen, remnants of primary magmatic quartz should be distinguished from metasomatic greisen-stage quartz in their higher intensity of CL and relatively higher Ti contents. A part of primary magmatic quartz may by secondarily purifiedviainfiltration of hydrothermal fluids and dissolution–reprecipitation processes. Such quartz parallels newly formed greisen-stage quartz in its chemical and CL properties; the share of greisen-stage quartz may by therefore overestimated.]]>