Oxygen Isotopes in Mantle and Crustal Magmas as
revealed by Single Crystal Analysis
Ilya Bindeman (University of Oregon, Eugene)
Perspective
• Oxygen is the major element in rocks, magmas, waters
• It provides “surface” (hydrosphere) signature to igneous rocks
• Underutilized in the past 10-20 years
• New microanalytical approaches gave a new start:
- Laser fluorination on single crystals 0.4-1 mg, ± 0.05‰
- Ion Microprobe spot analysis 2-30 mm, ±0.18-0.24‰
18O/16O ratios of important ox ygen-conta ining rese rvoirs (from Hoefs, 1 99
M
meteoric water
ocean water
sedimentary rocks
metamorphic rocks
high-18O magmas
low- 18 O magmas
granitic rocks
basaltic rocks, mantle
-50
-40
-30
-20
-10
0
10
20
30
18O, in ‰
18O =
[(18O/16O) Sample _ (18O/16O)
(18O/16O) Standard
Standard: sea water
Standard ]
x 1000
40
Experimentally-determined
Isotope fractionation between
minerals and melts as a
function of temperature
T, °C
1000 700
13
500 400
300
12
11
10
Quartz-Magnetite
1000 ln
9
1000 ln ≈ D18OMineral-Melt =
8
Albite-Magnetite
7
18Omelt – 18Omineral =
Anorthite-Magnetite
6
5
6
10
= 2A
T
Quartz-Zircon
4
Anorthite-Olivine
3
Rhyolite-zircon
2
Basalt-Olivine
Quartzrhyolite Albite-Muscovite
1
0
1
2
106/T2, K-2
3
4
Isotope fractionation as a
function of temperature
5.9
Plagioclase
C
D18Omelt-Plagioclase
18O, ‰
5.7
5.0
m e l t
B
D18Omelt-olivine
A
Olivine
T, °C
Tq
Isotope Equilibria:
D18Ogroundmass-olivine = 18Ogroundmass – 18Oolivine
D18Ogroundmass-plagioclase = 18Ogroundmass – 18Oplagioclase
D18OPlagioclase-olivine = 18Ogroundmass – 18Oplagioclase
An Equilibrium magma system: Bishop Tuff
Individual phenocrysts in individual pumice clasts
quenched in air
9
Quartz
18 O ‰ VSMOW
8
7
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Calculated Melt
6
Zircon
5
CPx
4
3
2
1
700
Magnetite
725
750 775 800
18O(Qz-Mt)
T, °C, DT°C
Bindeman and Valley, 2002, CMP
825
©Julie Roberge
The most diverse magma system: Yellowstone
18O zircon anatomy of latest Yellowstone volcanism
8
LCT
Quartz
6
MBB
DR
SBB
Glass
Eq zircon
±2s
normal-18O magmas
SCL
4
2
0
-2
Caldera Collapse
18O ‰ VSMOW
Zircon Core s:
CF
SP
Central Plateau
lavas
Upper Geyser
Basin lavas
-4
0.60
0.5 0
0.45
0.25
0.2 0
0.10
Age, Ma
Ion Microprobe Data on zircons
Bindeman et al. JPet, 2008
Single Crystals and in situ methods
- what’s new and are we “there” yet?
1 mg
Spot diameter (x depth), mm
1.0
0.5
0.3
10 30x6
0.1
2
Typical
Igneous
Crystals
NanoSIMS
Small radius
Large
ion
radius
microprobes
ion
microprobes
0.4
Continuous flow
GSMS analysis
Dual inlet GSMS analysis
UV laser
fluorination
0.1
Conventional
Ni rod bombs
CO2 laser
fluorination
Precision
Precision, ‰, 1 st dev
1x1
Single crystal radius or spot size, mm
0.05
4
100
picograms
0.01
0.1
1
Sample size, mg
10
Effort (time, $$$, goal)
Toward the Equilibrium:
Processes governing Isotope
exchange:
- Intracrystalline diffusion
- Solution-reprecipitation
Which is more important?
18O, ‰
6
0.69±0.03Ma
1
4
7
4
2
3
0
2
5
6
-2
0
50
100
Distance, mm
8
T, °C
Diffusion Coefficient, m2/s
1200
-15
-14
1000
Cations in olivine
Fe-Mg, Mn, Ca, Ni
-16
Olivine
- Oxygen diffusion coefficients
span four orders of magnitude
Quartz
Albite
- Crystal sizes span >1 order of
magnitude (e.g. 0.2 mm -2 mm)
Anorthite
-18
Diopside
X2
Sphene
-20
Zircon
-22
6
7
Diffusion
750
8
9
10
10000/T
Data is from: Zircon: Watson and Cherniak, (1997) wet;
Sphene: Morishita et al. (1996); Quartz: Farver and Yund
(1991), wet; Olivine: Ryerson et al. (1989), QFM;
Diopside: Farver (1989); Anorthite and albite: Elphick et
al. (1988; 1986) wet.
2
X
~Dt t~—
D
An example of quantification the isotope reequilibration by
diffusion by successive air abrasions: retrieving cores
airabraded
7
core
Zircon
1 ky
5 ky
core
18 O, ‰
6
10 ky
20 ky
5
30 ky
50 ky
4
0
20
40 rim
Radius ( mm)
Solved numerically for diffusion in a sphere. Diffusion coefficients are from Watson and Cherniak, 1997, T= 850°C
Solution-Reprecipitation
Evidence for Solution-Reprecipitation:
Crystal CL or zoning:
Concave up CSD indicative of annealing:
Quartz
Zircon
Crystals extracted from quenched individual pumice clasts
Recognizing Oxygen Isotope disequilibria:
-single crystal analysis: diversity
-coexisting minerals and groundmass: D18O at equilibrium?
-In situ analysis of crystalline domains: zoning or no zoning
Using Oxygen Isotope disequilibria:
• Identify crystal sources
• Quantify rates
• Origin of magma, its assembly, its residence time
• How shallow or how deep
Case Examples
- Silicic and basaltic magmas are assembled in isotopicallydistinct batches, with distinct crystal populations
- These crystals reside for 100-1000 years exchanging
oxygen with the assembled melt before eruption
- Large volume magma chambers can form rapidly in very
shallow crust, affected by meteoric hydrothermal systems,
uniquely fingerprinted by low-18O values
Olivine-melt isotope disequilibria in Basaltic systems
(1) Large fissure eruptions of Iceland
Laki: The smallest large igneous province…
Laki, 15 km3,
1783-4 AD
“The cause of this universal fog is not yet ascertained,…: or whether it was the vast
quantity of smoke, long continuing to issue during the summer from Hecla in Iceland,
or that other volcano…..” Franklin B. (1784) Meteorological Imaginations and
Conjectures Manchester Lit. Phylos. Soc.Mem Proc 2, 122.
Grimsvötn-Laki system
Laki Impacts:
•June 8, 1783 to February 7, 1784
•15km3 of magma
•122 Mt of SO2, 8Mt F2
•1.3°C cooling of the Northern Hemisphere
•French Revolution? American Independence?
Subparallel fissure systems of Iceland and
associated central volcanoes
Grímsvötn
Vatnajökull
Laki
Pleistocene Hyaloclastites and Holocene basalts
Burfell table Mt
ICE
3000 BC
lava 3.12‰
7000 BC
lava 3.6‰
Mantle: 5.5‰
Hyaloclastites
0-2‰
Hyaloclastite texture
Grimsvötn-Laki system:
Mantle melt
18 OOlivine :
MORB
Iceland
Plume
18O, ‰
5.0
Glass
Plag
4.0
Olivine
Cpx
3.0
Eq. Plag
Equilibrium Olivine
2.0
1455
1200
1505
1783-4
Calendar Year, AD
2004
1996
1998
 18 O, ‰
Grimsvötn-Laki system:
- Individual Olivine “pheno”crysts in15km3 Laki basalts span 3‰ range
- Exhibit compositional Fe-Mg homogeneity Fo75
- Diverse 18O plagioclase in tephras from the subglacial Grimsvotn caldera.
 18 O Olivine
96-Laki
MORB
Iceland
Plume
L36
5.0
:
Sing le crystals
and size fractions:
L14
Glass
P lag
4.0
Olivine
Cpx
3.0
Eq. Plag
Equilibrium Olivine
2.0
1455
1200
1505
1783-4
2004
1996
1998
Calendar Year, AD
Bindeman, Sigmarsson, Eiler 2006, EPSL
“Pheno”cryst-melt 18O disequilibria in other fissures
6
Laki
Veidivotn
Eldgja
mantle olivine
Olivine, 18O, ‰
5
4
• Severe 18O heterogeneity
and zoning in olivine
• Olivine-groundmass
disequilibria
• Plagioclase-olivine disequilibria
3
equilibrium
2
3
3.5
4
4.5
Glass, 1818O,
Groundmass,
O,‰
‰
Ion p robe olivine
Laser Ol
Laser Pl
Bindeman, Gurenko et al 2008 GCA
low 18O, Fo
core
Other Large
volume
fissure basalts:
Fe/Mg and 18O
zoning in olivines
High 18O, Fo
core
Oxygen vs Cations Exchange
@1160°C
1
18O/16O
Laki,
Eldgja
exchange:
Ol bulk
Ol cores
Ol, Fe-M g, bulk
Ol, Fe-M g, cores
Ol, Ni, bulk
Xenocrysts
1000
10000
time, yrs
100
10
1
Ol, Ni, cores
0.1
0.1
0.01
Vol. Fraction Exchanged
Mineral-Diffusive timescales:
Short olivine residence time
Other large volume basalts
(2) Olivine-melt disequilibria in high-18O basalts of
Klyuchevskoy Volcano, Kamchatka
Severe olivine-melt disequilibria in high-18O basalts
-basalts have high- 18O values
-diverse through time
-mixing between high-Al, high-Mg basalts, cumulates
from Auer et al. 2009
(3) Hawaii:
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Hawaii:
From Garcia et al. 1998
Single crystal isotope analyses demonstrated far greater
diversity of melts than bulk methods
40
HH95
E01
Frequency
30
Hawaii
20
Kamchatka
10
Iceland
0
1
2
3
4
5
6
7
18 O(Olivine), ‰
8
9
Silicic Igneous Systems:
18O diversity in zircons from major tuff units
4
rims
4
±1st dev
cores
2
3
±1st dev
2
900 km3
0
2.5
3
3.5
4
18
 O‰
1000 km3
3
4.5
5
Lava Creek tuff
cores
±1st dev
4
rims
4
18 O ‰
5
6
Huckleberry Ridge tuff
Member-C
4
Number
6
Number
2500 km3
1
0
8
Ammonia
Tanks tuff
Huckleberry Ridge tuff
Member-A
Number
300 km3
6
Number
5
Mesa Falls tuff
Number
8
2
±1st dev
3
2
1
0
2.5
3
3.5
4
18 O ‰
4.5
0
3.5
4
4.5
5
18 O ‰
5.5
6
Equilibrium zircon value
Zircon diversity with respect to 18O vs eruptive volume
6
300
HRT
LCT
MFT
100
0
CP. late
40
CP, early
3
time
AT
Number of Batches
residence
UB, Canyon flow
18O zircon
diversity in ‰
Batch
1000 2500
Erupted volume km3
Summary: What have we learned?
• Tremendous isotope heterogeneity and
disequilibria - blessing or a curse?
– Identification of sources - high, low, normal 18O
– Identification of the process (e.g. hydrothermal)
– Timescales - duration of magma segregation/residence
Xenocrysts vs. Antecrysts vs. Protocrysts vs. Phenocrysts
• Phenocrysts = xenocrysts “annealed beyond
recognition”
• Isotope heterogeneity on the order of 0.1-0.2‰
is always present in nature
Single crystal and in situ isotope analysis
address bigger questions:
• Short magma generation timescales
• Diverse sources of crystals
• Recycling of crust
• Shallow magma petrogenesis
How to Proceed?
• Best to proceed by single crystal analysis to
demonstrate:
- equilibrium mineral-melt and mineral-mineral relationship
- lack of crystal-to-crystal heterogeneity
• Isotope heterogeneity is usually found in rocks
that are fingerprinted by either high- or low-18O
AND
• Oxygen isotope is the only evidence
- Normal 18O rocks may have the same origins and processes but
we just simply cannot recognize them
Shallow Crustal Petrogenesis
Shallow - need to do significant mass transformation in the upper crust
-Taboo for thermal modelers
Rapid processes - Need to segregate magmas rapidly in the order
100-1000 years
However, they may erupt or reside and anneal for 100ky or more
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
September 9-13, 2009 Penrose conference:
“Low 18O rhyolites and crustal melting: growth and
redistribution of the continental crust”
10,000 km3
of low-18O
rhyolites
Klyuchevskoy volcano in winter
Spasibo!
Thanks to:
Kathryn Watts
Erwan Martin
Jim Palandri
Andrey Gurenko
John Eiler
John Valley
Fred Anderson
Olgeir Sigmarsson
Axel Schmitt
Paul Wallace
Maxim Portnyagin
High Silica large-volume rhyolites:
Hard to produce
Easy to recycle
900
San in, liquidus
850
T, °C
1.5 kbars
3wt% water
Mr = DTbC +DXbL
Mb
DTrC
800
Qz in
750
Plag in
water in
"bulk" melting Qz+San+Plag
700
650
0
25
50
% crystals
75
 18 O, ‰
Short melt residence time:
Yonger than 8000 yr
Older than 100 y
(226Ra/230Th)= 1.11 (210Pb/226Ra)= 1.00
 18 O Olivine
96-Laki
MORB
Iceland
Plume
L36
5.0
:
Sing le crystals
and size fractions:
L14
Glass
P lag
4.0
Olivine
Cpx
3.0
Eq. Plag
Equilibrium Olivine
2.0
1455
1200
1505
1783-4
2004
1996
1998
Calendar Year, AD
Quantifying rates of solutionreprecipitation
Annealing quartz and zircon in Bishop Tuff
Simakin, Bindeman JVGR 2008
Isotopic zoning in zircons from Yellowstone Caldera
5
4
18O, ‰
Core
9
1
3
2
5
10
1
0
Rim 8
-1 4 3
2
11
-2
0 50 100 150 200 250
Distance, mm
18O, ‰
6
0.69±0.03Ma
1
4
7
4
2
3
0
2
5
6
-2
0
50
100
Distance, mm
8
Yellowstone Calderas
1.
Huckleberry Ridge tuff HRT, 2 Ma,
2500 km3
2. Mesa Falls tuff, 1.3 Ma, 300 km3
3. Lava Creek tuff, LCT, 0.64 Ma, 1000 km3
Nested calderas of Yellowstone: collapses and post-caldera lavas
I collapse
Pre-2.1 Ma
landscape
0.64 Ma caldera rim
III collapse
Floor of Yellowstone
caldera, lake sediments
post-caldera West Yellowstone rhyolite flow, 50 km3, synglacial
Post caldera voluminous rhyolites
Origin of Yellowstone volcanism 0.64-0 Ma
MFT batholith?
HRT batholith?
Variable 18O magma batches ~305ka that represent variably
hydrothermally altered (variably 18O depleted) rocks
Plutonic example of batch assembly?
Idaho Batholith (King and Valley, 2001)
Natural variability vs. Analytical precision:
Is there a threshold?
• In Isotope Geochemistry we “look through” fractionation
effects to fingerprint sources
• ~0.1‰ precision is routine
• Isotope heterogeneity on the order of 0.1-0.2 permil is
always present and is unavoidable and is due to:
“Closed” system processes
– Minor interaction with hydrothermally-altered carapace
– Residual zoning due to inheritance and annealing of xenocrysts
– Inheritance of “hot” or “cold” protocrysts into magma and insufficient time to
reestablish isotope equilibria
– Early “closure” of high-closure crystals
– Differing paths of crystallization-differentiation (P and PH2O)
– Magma “auto”mixing
– Rapid volatile loss and volatile-driven crystallization
– Kinetic fractionation vs equilibrium fractionation
– …
Effect on 18O
(?)
Average of single crystal analyses will provide better constraint
on the overall question about sources
Timescale 2:
Burial
The Shallow Recycling Machine:
Iceland, Yellowstone, Early Earth
STACKING
B
U
R
I
A
L
-Progressive burial by caldera collapses,
rifting and overloading
- Hydrothermal alteration serves as a flux
to cause melting
- Glassy, porous nature of these rocks
makes remelting and disaggregation easier
REMELTING
REACTIVE ASSIMILATION
LOOSE COHESIVENESS
RECYCLING
Timescale 1:
Remelting-Eruption
We need to build thermo-mechanical models that will explain large and
growing number of observation on shallow crustal remelting
On volcanic-plutonic connection and origin of high-silica rhyolites
Positive 18O vs. Forsterite correlation: assimilation
of evolved composition, and magma mixing
6
System, lava, Sample
Thordarhyrna, Nuprahraun 29
18
Olivine,  O, ‰
5
Elgja 10-11
Vedivotn, Vatnaoldur, 900AD, 13,15
Vedivotn, 7000 BP, 17
4
Vedivotn, 3000 BP, 18
Vedivotn, 2000BP, 14
Pre-Laki hyaloclastites, 27-28
3
Laki, 96-Laki
65
70
75
80
Fo, %
85
90