082609_ASU-SESE_Tim Grove (MIT)

Date: 26 Aug, 2009
Speaker: Tim Grove (Massachusetts Institute of Technology)
Title: Melt Generation Processes in Subduction Zone
Abstract: New experimental results and evidence from field investigations of subduction zone volcanoes provide insight into the processes that lead to the volcanoes at convergent margins. The experimental evidence on the pressure and temperature of mantle peridotite melting in the presence of H2O illuminates new processed that transport H2O to depth in subducted zones and new insights into the beginning of melting in the mantle wedge above the subducted slab. When combined with geochemical evidence from arc lavas a model of hydrous flux melting can be constructed that allows one to understand the unusually high H2O contents observed in arc magma (4 to 6 wt. % H2O). These experimental and geochemical constraints also allow one to understand the physical factors control the location of volcanoes in subduction zones.

Note: H2O and Chlorite play critical rules in the Subduction Zone down to 150 km from surface. The thing impressed me the most is "what do you think how deep the slabs go down in subduction zones to create volcanoes?" The range is 60-130 km and the average is 108 km.