Journal of

GEOsciences

  (Formerly Journal of the Czech Geological Society)

Original paper

Karel Pacák, Jiří Zachariáš, Matěj Němec

Titanium-oxide activity during the formation of gold-bearing quartz veins: evidence for closed system behavior

Journal of Geosciences, volume 67 (2022), issue 1, 19 - 32

DOI: http://doi.org/10.3190/jgeosci.340

Titanium contents of both vein and magmatic quartz from five Bohemian gold deposits with known P-T history were used to calculate/discuss the titanium oxide activities ( ) of natural quartz formed in the absence of Ti-buffering phases at 250-550 °C and 0.1-4 kbar.
Data suggest significant variations in during vein quartz formation, due to variation of P, T, growth rate and . Negative correlation between and quartz formation temperature was documented for intrusion-related gold deposits, implying quartz precipitation under closed-system conditions (i.e., without substantial equilibration of the ascending fluid with surrounding rocks). We propose a relationship for quantifying disequilibrium quartz formation that can be readily applied to quartz with known P-T history. The relationship was tested on natural samples exhibiting both rapid and slow crystallization. An example of extreme Ti enrichment (up to ~30 ×) in quartz, associated with its rapid growth, is described and discussed.