Behaviour of water and fluid-mobile elements in subduction zones

Please see the Elements in April 2013: http://www.elementsmagazine.org/

Arc volcanism and geochemical processes

Arc volcanoes discharge large quantities of H₂O, CO₂ and SO₂. Some volcanoes discharge huge SO₂, some are not. Some arcs are very fertile in base metals, producing many metallic deposits.

I am interested in:

Why some arcs are very fertile,
How metallic elements are transferred from subducting slabs to arc magmas via sub-arc mantle (i.e., element recycling),
How volatile elements are subducted and moved to the interior of mantle wedges where arc magmas are generated.

To understand these processes and paths, I examine:

Forearc mantle peridotites (serpentinites, xenoliths),
Primitive arc magmas.

Study 1. Forearc mantle peridotites

Studied regions: Himalayas, Alps, Cuba, Dominican Republic, Japan, Newfoundland, Turkey, eastern China.

Key points:

Serpentin is stable down to ~130 km depth and can contain up to 17 wt% water.
Acts as a reservoir of water and fluid-mobile elements (As, Sb, Sr, Pb).
A layer of serpentinites forms at the base of mantle wedges as slabs release volatiles.
These serpentinites are dragged by mantle flow and eventually dehydrate, releasing fluids that generate arc magmas.

They are brought to the surface as:

Xenoliths,
Massifs in ophiolitic terranes.

They provide insight into subduction geochemistry.

Researcher: Jian Wang (PhD on subarc mantle compositions)
Publications: Contributions to Mineralogy and Petrology, Lithos, and Mineralogy and Petrology
Current position: Professor, Jilin University

Study 2. Composition of primitive arc magmas

The subarc mantle is studied using:

Primitive arc magmas,
Xenoliths from explosive arc volcanics.

Example study:

Cees Jan de Hoog: Primitive mafic magmas at Mount Pinatubo, using melt inclusions.

Additional Topics

Study of mantle wedges, active continental margins, element transfer during subduction.

Selected Publications