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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
