Le Geotop - Dr. Zoltan Zajacz: Sulfur in magmas... (24-11-2017)

Dr. Zoltan Zajacz: Sulfur in magmas... (24-11-2017)

 

Dr. Zoltan Zajacz, University of Toronto

Sulfur in magmas: from porphyry Cu-Au deposits to ‘excess sulfur’ in volcanic eruption

Vendredi 24 novembre 2017 à 15h30 / Friday, November 24, 2017, 3:30 pm

Redpath Museum Auditorium, 859 Rue Sherbrooke O, Université McGill

Résumé / Abstract :

Sulfur is a minor volatile constituent in magmas, yet it is a key player in magmatic-hydrothermal ore genesis and also is primarily responsible for the climatic and environmental impact of volcanic degassing. This presentation will quantitatively address the geochemical behavior of sulfur during the differentiation and degassing of magmas in the Earth’s upper crust, including aspects such as partitioning between silicate melts and aqueous fluids, the stability of magmatic sulfides and anhydrite in volatile-saturated magmas, and the dynamic redistribution of sulfur between various phases during magma evolution. The above information will be presented alongside with data highlighting the role of S in the mass transfer of chalcophile ore metals such as Au, Cu and Ag in magmatic and associated hydrothermal systems. In addition, the presentation will address what the most favorable conditions are to yield volcanic eruptions that introduce anomalously high amounts of sulfur into the Earth’s atmosphere.