Petrologic Constraints on Mantle Temperature and

Water ContentMarc 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

H2O (wt.%)

CO

2 (w

t.%

)

MORB and seamount glassesEaster Microplate

Kingley et al. 2002

H2O Storage Capacity

Hirth & Kohlstedt, 1996

Aubaud et al., GRL, 2004

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

0

50

100

150

200

250

0 200 400 600 800 1000 1200

H2O (ppm wt.)

Initial depth of melting (km)

1550 °C

1450 °C

1350 °C

RIDGE

PLUME

Tp

MELT Experiment beneath EPR

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

Dasgupta & Hirschmann (2006) - Nature

Carbonated Melt Catalyzes Grain Growth

Subsolidus Supersolidus

Dasgupta et al. (2004) - EPSLDasgupta et al., 2004

Dasgupta & Hirschmann (2006) - Nature

Origin of Chemical Lithosphere and Volatile induced Melting of PeridotiteHirth & 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)

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Tim Grove - unpublished results(thanks, Tim!)

Elliott, 2003

High Temperature Melt or FluidTransfer from the Slab

Kelemen et al. 2003

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Davies&Stevenson, 1992 Mibe et al., 2001

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Kelemen et al., 2003

Temperatures at the baseof the crust based onmetamorphic thermobarometry

(Elkins Tanton et al., 2001)

Mt. Shasta-Medicine Lake

High Temperatures in Arcs- Petrologic Evidence Location Max T

(°C) P

(GPa) Method So urce

Banda 1320 1.2 Melt Inclus ions

Sisson&Bronto, 1998

Cascades 1450 2.2 Inverse Exper iments

Elkins Tanton e t a l., 2001

Japan 1320 -1360

1.7 -2.3 Inverse Exper iments

Tatsu mi et a l. 1983

Japan 1325 1.2 Inverse Exper iments

Kush iro, 1987

N. Tonga 1480 1.5 Inverse Exper iments

Fa lloon&Danyus hevsky,200 0

Aleut ians 1300 1.2 Inverse Exper iments

Draper & Jo hnston, 1991

Thanks for listening…..