Petrologic Constraints on Mantle Temperature and Water Content Marc Hirschmann University of Minnesota

Stixrude&Lithgow-Bertelloni, 2005

Stixrude&Lithgow-Bertelloni, 2005

Oceanic Crust Production Langmuir et al., 1992; Asimow et al., 2001

Trace amounts of H2O enhance melting…. Hirth & Kohlstedt, 1996; Asimow & Langmuir, 2003

Saal et al., 2002 MORB and seamount glasses Easter Microplate CO2 (wt.%) Kingley et al. 2002 H2O (wt.%)

H2O Storage Capacity

Hirth & Kohlstedt, 1996

Aubaud et al., GRL, 2004

Hirth & Kohlstedt, 1996 Aubaud et al., GRL, 2004

MELT Experiment beneath EPR Gu et al. (2005) The MELT Seismic Team (1998)

Dasgupta & Hirschmann (2006) - Nature

Carbonated Melt Catalyzes Grain Growth Subsolidus Supersolidus Dasgupta et al., 2004 Dasgupta et al. (2004) - EPSL

Dasgupta & Hirschmann (2006) - Nature

Origin of Chemical Lithosphere and Volatile induced Melting of Peridotite Hirth & Kohlstedt (1996) Aubaud et al., 2004 Peridotite Dehydration is aided by Partial Melting

Dasgupta & Hirschmann (2006) - Nature

Deep Carbonated Silicate Melting Beneath Ridges Transition from carbonatite to carbonated silicate melts at 3 GPa Silicate Melting is enhanced in presence of carbonate Dasgupta & Hirschmann (submitted)

Deep Carbonated Silicate Melting & H2O Extraction Beneath Ridges

Schmidt+Poli, 1998

Honshu - Van Keken, 2003

(from Gaetani+Grove, 2003)

Tim Grove - unpublished results (thanks, Tim!)

High Temperature Melt or Fluid Transfer from the Slab Elliott, 2003

Kelemen et al. 2003

Davies&Stevenson, 1992 Mibe et al., 2001

Temperatures at the base of the crust based on metamorphic thermobarometry Kelemen et al., 2003

Mt. Shasta-Medicine Lake (Elkins Tanton et al., 2001)

Thanks for listening…..