Melting Regions of the Mantle Terry Plank: LDEO with C-T. Lee (Rice) D. Forsyth (Brown) E. Hauri (Carnegie ) K.Fischer (Brown) G. Abers (LDEO) D.Wiens (Wash U)

Boundary Layers and Melting b.holtzman 2009 Boundary layer dynamics drive melting melt extraction creates lithosphere

East Pacific Rise MELT Experiment Forysth et al (1998) Japan Volcanic Arc P-wave tomography Zhao et al (1992)

What does RED mean? 1.Hot ? 2.Wet? 3.Melt ? from Yang and Forsyth, 2006, JGR Southern California shear velocity anomaly (70-90 km depth)

Temperature (°C) Pressure (GPa) Melt Thermobarometers dry solidus Solidus from Hirschmann (2000) olivine-melt thermometer MgO ol MgO liq D = = f (T) 40 km /- 30 °C

Temperature (°C) Pressure (GPa) Melt Thermobarometers dry solidus Solidus from Hirschmann (2000) olivine-melt thermometer silica-melt baromometer MgO ol MgO liq D = = f (T) Mg 2 SiO 4 ol + SiO 2 liq = Mg 2 Si 2 O 6 opx a(SiO 2 ) liq ~ 1/K Thermobarometer parameterizations from C-T Lee et al, EPSL, km /- 0.2 GPa +/- 30 °C

Temperature (°C) Pressure (GPa) Melt Thermobarometers dry solidus Solidus from Hirschmann (2000) olivine-melt thermometer silica-melt baromometer MgO ol MgO liq D = = f (T) Mg 2 SiO 4 ol + SiO 2 liq = Mg 2 Si 2 O 6 opx Thermobarometer parameterizations from C-T Lee et al, EPSL, wt% H 2 O 40 km a(SiO 2 ) liq ~ 1/K

For H 2 O, we need melt inclusions in olivine from well-quenched tephra

Benjamin, Plank, Wade, Hauri & Alvarado (JVGR, 2007)

1. East Pacific Rise 3. Central American Arc 4. Basin and Range Examples of Melting Regions 2. Back-arc Basins

1.East Pacific Rise (MELT and GLIMPSE) Ridge Harmon, Forsyth, Weeraratne (EPSL, 2009) Shear velocity model

Temperature (°C) Pressure (GPa) oceanic crust Pacific off-axis Nazca off axis on-axis 80 km 50 km 110 km 15 km P-T calculated from thermobaromters in Lee et al (EPSL, 2009): Fo 90, 100% Fe 2+ ; H 2 O = 0.1 wt% Most MORB data from Sinton et al (JGR, 1991) and Hall et al (G3, 2006); all > 8.2 wt% MgO method in LKP92 and Wiens et al (2006) 100 ppm H 2 O

Ridge Harmon, Forsyth, Weeraratne (EPSL, 2009) Shear velocity model dry solidus magmas solidus with 100 ppm H 2 O T p = 1470°C

km Harmon, Forsyth, Weeraratne (EPSL, 2009) Shear velocity model Ridge dry solidus magmas solidus with 100 ppm H 2 O Temperature (°C) ppm H 2 O % Melting km T p = 1470°C Wet melting model after Langmuir et al (2006)

From Conder et al (JGR, 2002) test dynamic models

Shear velocity (km/s) Depth (km) Model that satisfies Q = 80; T p = 1350°C derived from Rayleigh waves melt? …or Tp = 1450°C After Yang & Forsyth (EPSL, 2007)

2. Back-arc Basins Wiens, Kelley & Plank (EPSL, 2006)

S wave velocity (km/s) N. Lau & N. Fiji Mariana Tr. & Scotia Wiens, Kelley & Plank (EPSL, 2006) (dry melts only) MELT

Wiens, Kelley & Plank (EPSL, 2006) S.EPR (MELT)? Temperature variations on Vs

3. Volcanic Arc Rychert, Fisher, Abers, Plank, Syracuse, Protti, Gonzalez, Strauch (G3, 2008) Syracuse, Abers, Fischer, MacKenzie, Rychert, Protti, Gonzalez, Strauch (G3, 2008)

Rychert, Fisher, Abers, Plank, Syracuse, Protti, Gonzalez, Strauch (G3, 2008)

Olivine-liquidus depression due to water from Medard and Grove (2007))

US Array: Transportable Array

from Deuker et al, 2001, JGR from Yang and Forsyth, 2006, JGR LV = Long Valley BP = Big Pine GT = Golden Trout C = Coso km depth

Lathrop Wells volcano 70,000 yrs old 18 km south of Yucca Mnt Yucca Mnt

Wang, Plank, Walker and Smith, JGR, 2002 Mantle Melting Profile Across B&R dark green columns = + ε (Nd) (astheno.)

120°W km Transect at 37°N Courtesy of Yingjie Yang ( Yang, Ritzwoller, Lin, Moschetti, Shapiro, JGR, in press )

120°W km Transect at 37°N BP Courtesy of Yingjie Yang ( Yang, Ritzwoller, Lin, Moschetti, Shapiro, JGR, in press )

120°W km Courtesy of Yingjie Yang ( Yang, Ritzwoller, Lin, Moschetti, Shapiro, JGR, in press ) Transect at 37°N BP LW SC °C 1.8 wt% H 2 O °C 3.2 wt% H 2 O °C 0.9 wt% H 2 O T p =1350 T p =1390 T p =1440

1. East Pacific Rise 3. Central American Arc 4. Basin and Range Examples of Melting Regions 2. Back-arc Basins presence of melt mantle Tp variations effect of water on Q mapping T, melt and H 2 O