Trace-element chemistry of barren and ore-bearing quartz of selected Au, Au-Ag and Sb-Au deposits from the Bohemian Massif
Abstrakt
The trace-element contents in gold-bearing and barren quartz veins from eight Au, Au-Ag and Sb-Au Variscan deposits in the Bohemian Massif have been determined in situ in order to evaluate the differences between the various types of gold deposits and discuss trace-element variations in the successive generations of quartz veins. The variability of Ti, Al, Ge, Li and Sb abundances obtained by Laser-Ablation Inductively-Coupled Plasma Mass Spectrometry (LA-ICP-MS) roughly correlates with the origin and the temperature of the mineralizing fluids.
The Al content ranges up to 4020 ppm (median value 230 ppm), while the Li content is generally low ( 450 degrees C) formation exhibit higher median values (similar to 10 ppm Ti) than medium-to-low (< 300 degrees C) temperature deposits (similar to 2 ppm Ti). A statistically significant threshold value (8 ppm Ti) has been recognized as an empirical tool for discriminating between them.
In terms of the Ti and Al contents, the studied Bohemian gold deposits fall within and in between fields of orogenic gold and porphyry deposit types.