Volatile Recycling at Subduction Zones Terry Plank, Lamont Doherty Earth Observatory The Subduction Factory.

Volatile Recycling at Subduction Zones

Terry Plank, Lamont Doherty Earth Observatory

The Subduction Factory

Is the Ocean Shrinking?

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60% ofstructurally-bound H2Oreleased

Hacker (2008) G3; Jarrard (2003) G3

Water Fluxes During Subduction

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60% ofstructurally-bound H2Oreleased

Hacker (2008) G3

Water Fluxes During Subduction H2O Output? H2O % in magmaMagma Mass Flux

0 1 2 3 4 5 6 7 8

Centam

H2O (least degassed) wt%

Arc Data: 2000

MORB

(SubFac Science Plan)

0 1 2 3 4 5 6 7 8

Aleutians

Centam

Marianas

Mexico

Tonga

Kamchatka

H2O (least degassed) wt%

Arc Data: 2009

MORB

3.9 wt% H2O +/- 1.0 (1 stdev)

Average Arc Growth Rates

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Suyehiro et al. (1996) Science

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Holbrook et al (1999) Geology

(km3/km/Ma)

Izu Arc

Aleutian Arc

23-33 (Reymer&Schubert, 1984)

75-82 (Holbrook et al., 1999)

59-61 (Dimalanta et al., 2002)

89-182 (Jicha et al., 2006)

Duration: 46 Ma

28 (Reymer&Schubert, 1984)

66 (Suyehiro et al., 1996)

56-60 (Dimalanta et al., 2002)

Duration: 47 Ma

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Th input (g/yr)

Th output (g/yr) = CTh * Magma Mass Flux

Hebert et al (2009)

100 km

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60% ofstructurally-bound H2Oreleased

Hacker (2008) G3

Water Fluxes During Subduction 4 +/- 1 wt% H2O arcs60 +/- 20 km3/km/Ma3.0E8 = 40 +/- 20% recycled to arc

0 300 600

Millions of years before present

200

400

600

800

1000

Relative sea levelchange (meters)

70%

40%

50%

Subduction of Water Lowering Sea Level

50% water recycled to surface

from Rupke et al. (2004)

Millions of years before Present

Global Sea LevelVariations

met

ers

Hallam (1982); and Wallman (2001)

Sea level fallover past ~ 600 Madue to subduction ofwater??

from Rupke et al, Earth and Planetary Science Letters (2004)

SizeofOcean

today

Oceangrowing

Oceanshrinking

hottermantle

coolermantle

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2% H2Oin 4 km mantle 5.7

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All serpentine-bound H2Obypasses arc?Hacker (2008) G3

Water Fluxes During Subduction

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2% H2Oin 4 km mantle 5.7

pastarc

0.5

2.5

5.4

Lose oceanIn 1.7 Ga!

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Wiens/Lizarralde MARGINS experiment

Subducting Carbonate and CO2 Cycling

GLOSS - global subducting sediment

Plank & Langmuir (1998)

Centam

Plank, et al (2002) Geology

Altered oceanic crust

Alt figure??

(1999) GCA

CO2 Output??

Figure from Wallace (2005) JVGR

Melt Inclusions - minimum CO2

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?

Benjamin et al. (2007) JVGR -- Irazu Volcano, Costa Rica

Global Flux Estimates from Wallace (2005) JVGR

C Flux in & out of the mantle

(Alt & Teagle, 1999; Sleep & Zahnle, 2001; Jarrard, 2003)

Courtesy of M. Hirschmann

Input Output

25%

Centam, CO2 flux from slab

Gorman et al (2006) G3

Shaw et al (2003) EPSL

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Typical CO2/3He in Centam despite major carbonate subduction

H2O Recycling

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REE/Th

CO2 Recycling

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• 40-60% returned to arc

• serpentine subduction?

• 25% returned to arc

• decarbonation?

• CO2 fluxes out volcanoes