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Volatile Recycling at Subduction Zones

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Volatile Recycling at Subduction Zones. Terry Plank, Lamont Doherty ... (Alt & Teagle, 1999; Sleep & Zahnle, 2001; Jarrard, 2003) Courtesy of M. Hirschmann ... – PowerPoint PPT presentation

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Title: Volatile Recycling at Subduction Zones


1
Volatile Recycling at Subduction Zones
Terry Plank, Lamont Doherty Earth Observatory
The Subduction Factory
2
Is the Ocean Shrinking?
3
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4
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5
Water Fluxes During Subduction
60 of structurally- bound H2O released
Hacker (2008) G3 Jarrard (2003) G3
6
Water Fluxes During Subduction
H2O Output? H2O in magma Magma Mass Flux
60 of structurally- bound H2O released
Hacker (2008) G3
7
Arc Data 2000
(SubFac Science Plan)
Centam
MORB
0
1
2
3
4
5
6
7
8
H2O (least degassed) wt
8
Arc Data 2009
Centam
Tonga
MORB
Mexico
Marianas
Kamchatka
Aleutians
0
1
2
3
4
5
6
7
8
H2O (least degassed) wt
3.9 wt H2O /- 1.0 (1 stdev)
9
Average Arc Growth Rates
Izu Arc
(km3/km/Ma)
28 (ReymerSchubert, 1984) 66 (Suyehiro et
al., 1996) 56-60 (Dimalanta et al.,
2002) Duration 47 Ma
Aleutian Arc
23-33 (ReymerSchubert, 1984) 75-82 (Holbrook et
al., 1999) 59-61 (Dimalanta et al., 2002) 89-182
(Jicha et al., 2006) Duration 46 Ma
10
Th output (g/yr) CTh Magma Mass Flux
Th input (g/yr)
100 km
Hebert et al (2009)
11
Water Fluxes During Subduction
4 /- 1 wt H2O arcs 60 /- 20 km3/km/Ma 3.0E8
40 /- 20 recycled to arc
60 of structurally- bound H2O released
Hacker (2008) G3
12
Subduction of Water Lowering Sea Level
50 water recycled to surface
from Rupke et al. (2004)
13
Global Sea Level Variations
meters
Sea level fall over past 600 Ma due to
subduction of water??
Millions of years before Present
Hallam (1982) and Wallman (2001)
14
Ocean shrinking
Ocean growing
Size of Ocean
today
hotter mantle
cooler mantle
from Rupke et al, Earth and Planetary Science
Letters (2004)
15
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16
2 H2O in 4 km mantle
5.7
17
Water Fluxes During Subduction
All serpentine- bound H2O bypasses arc?
Hacker (2008) G3
18
Lose ocean In 1.7 Ga!
past arc
0.5
2.5
2 H2O in 4 km mantle
5.7
5.4
19
Wiens/Lizarralde MARGINS experiment
20
Subducting Carbonate and CO2 Cycling
21
GLOSS - global subducting sediment
Plank Langmuir (1998)
Centam
Plank, et al (2002) Geology
22
Altered oceanic crust
Alt figure??
(1999) GCA
23
CO2 Output??
Figure from Wallace (2005) JVGR
24
?
Melt Inclusions - minimum CO2
Benjamin et al. (2007) JVGR -- Irazu Volcano,
Costa Rica
25
Global Flux Estimates from Wallace (2005) JVGR
26
C Flux in out of the mantle
Input
Output
25
(Alt Teagle, 1999 Sleep Zahnle, 2001
Jarrard, 2003)
Courtesy of M. Hirschmann
27
Centam, CO2 flux from slab
Gorman et al (2006) G3
28
Typical CO2/3He in Centam despite major carbonate
subduction
Shaw et al (2003) EPSL
29
H2O Recycling
CO2 Recycling
40-60 returned to arc serpentine
subduction?
25 returned to arc decarbonation? CO2
fluxes out volcanoes
REE/Th
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