Professor Richard Arculus's Public Lecture
Date: 3 November 2009
Venue: The Kenworthy Room, St Mary's College
Title: Water and Volcanism
Water and volcanism are intimately linked: lava in contact with water (lakes, glaciers, oceans) explodes violently; low pressure degassing of water previously dissolved at high pressures drives extraordinarily energetic eruptions; water-rich fluids escaping from magmas carry dissolved metals and sulfur – on cooling, these can precipitate as sulfides either in the oceans around “black smokers” or within the crust to form some of our largest ore deposits.
On a planetary scale, recycling of water from the oceans into the crust and thence via subducted tectonic plates deep within the Earth to be liberated, triggering melting beneath chains of volcanoes (“arcs”) such as the Pacific Ring of Fire, is crucial in the evolution of the planet. The solvent properties of water in this cycle are essential in controlling the chemical composition of arc magmas, and ultimately control the composition of the continental crust: the aphorism “no H2O, no granite, no oceans, no continents” summarises our present understanding of the processes involved.
The level of this talk, which is included in the 'Water on the Earth and Beyond' public lecture series, will be aimed at a general audience to encourage everyone from undergraduates, non-science faculty and the interested general public to attend.