Diamonds and the Geology
of Mantle Carbon
Steven B. Shirey1 Pierre Cartigny2 Daniel J. Frost3
Shantanu Keshav4 Fabrizio Nestola5 Paolo Nimis5
D. Graham Pearson6 Nikolai V. Sobolev7 Michael J. Walter8
1
Department of Terrestrial Magnetism,USA
2
Institut de Physique du Globe de Paris, France
3
Bayerisches Geoinstitut, Germany 4Geosciences Montpellier, France
5
University of Padua, Italy 6University of Alberta, Canada
7
Sobolev Institute of Geology and Mineralogy, Russia
8
University of Bristol, UK
RiMG chapter of “Carbon in Earth”
Unique aspects of diamonds
•
The flagship of carbon minerals in Earth
•
Deepest samples (120 to 800 km)
•
Old samples (100-3500 million years old)
•
Most resistant to later geologic processes
•
Unique potential to trace mantle processes
•
Form under special conditions, (e.g. metasomatic)
Fronts for diamond research
•
Element partitioning during diamond growth
•
Inclusion paragenesis and diamond age
•
Source of carbon and its geologic significance,
•
Speciation of diamond-forming fluids and mantle fO2
•
Deep diamonds and relation to geodynamic processes
•
Experiments on diamond formation by fluids and melts
•
Nanostructural characteristics of diamond
Components of Diamonds and the Mantle
Geodynamics of Carbon (DMGC) project
Crystallography
P,T conditions for diamond crystallization and inclusion-host relationships
Experimental petrology
movement of C through the mantle with melt and fluid into diamond
Geochemistry
age and geochemical constraints on C-bearing fluids in the mantle
Stable isotopes
detect primitive and recycled components and isotopic fractionation
Nanostructure
diamond formation at the crystal chemical level
Diamonds of the world
Diamond types
lithospheric
superdeep
alluvial
UHP crustal
impact
exposed Archaean crust
well-defined cratons,
part of composite cratons
composite craton outline;
Proterozoic amalgamation
craton correlations from
Pangea
RiMG Chapter 12 of “Carbon in Earth”
Diamonds in relation to mantle keels and subduction
volcanic chain
mid-ocean ridge
140
G
km G
D
LA
D
42
up
B
pe
0k
m
tran
67
rm
an
Ol
+
siti
0k
on
m
0k
m
low
er
ma
Grt
+
Ol +
tle
zon
Ma
Mg
ntle
j+
Cp
craton
Chr
±C
px
t
Gr
±O
px
±S
f
p
+C
x+
Sf
c
eri
h
sp tle
o
h
n
lit
ma
Ma
C
j+
Pv
C
v±
d+
Ma
+F
eP
j+
er
kimberlite
p
Ca
+C
j
Ma
Pv
+
aP
v
l) +
Mg
basalt/eclogite
i±
St
itio
C
a
Pv
TiP
a
C
v+
P
a
C
rt
aF
an
m
r
pe
p
u
iPv
T
Ca
+
x
ns
a
r
t
x
e
Wd
s/R
w
90
subduction
+
e
low
L+
A
N
r
tle
o
nz
ne
n
ma
tle
i
St
eA
F
(
v
P
lithospheric mantle
convecting mantle
RiMG Chapter 12 of “Carbon in Earth”
Internal textures of diamonds
coated
128
moncrystalline
superdeep
M. Kopylova et al. / Earth and Planetary Science Letters 291 (2010) 126–137
Fig. 3 CL images revealing the
internal structure of Collier 4
diamonds. Also shown on the
diamond images are d13C values
(% relative to PDB) as
determined by SIMS analysis.
a J2 diamond with weak
octahedral zonation and large
change in d13C from core to rim,
b weakly zoned J3 stone with
deep system of internal cracks,
c J6 broken and resorbed
crystal, d J8—broken, deformed
and resorbed diamond, e J9
diamond with ‘sheared’
zonation described in the text
and large change in d13C from
core to rim
Fig. 1. Scanning electron microphotographs of cathodoluminescence in two samples of
the studied Congo diamonds. Dots indicate positions of analysed inclusions, scale bar is
0.6 mm. Dashed line in sample 28 separates the inner fibrous coat with silicic
compositions of inclusions from the outer coat with carbonatitic inclusions.
uniform in all fluid inclusions of this sample and truly is a characteristic
of the fluid rather than controlled by a higher mode of trapped Fe-rich
minerals. Analysis of all correlations between elements suggests
they group into 3 components, silicic (mainly SiO2 + Al2O3), carbonatitic
(mainly Na2O + MgO+ FeO+ CaO + P2O5 + SrO) and saline (mainly
K + Cl). Silica strongly correlates with Al2O3 (Fig. 2B), but negatively
correlates with CaO (Fig. 2A), P2O5, Na2O and MgO. Calcium oxide
correlates with P2O5 (Fig. 2C) and SrO, whereas MgO correlates with
Na2O (Fig. 2F) and FeO (Fig. 2E). All these elemental trends imply that
the silicic component is strongly anticorrelated with the carbonatitic.
The saline elements K and Cl correlate with each other (Fig. 2D) but vary
independently of carbonatitic and silicic components as indicated by the
absence of correlations between K2O and CaO, or K2O and SiO2. BaO
correlates with Cl and K2O. This may imply partitioning of BaO into the
saline component, or its incorporation in K and Cl-bearing mica which is
the main daughter mineral of the silicic component. Barian mica
kinoshitalite is found in the studied samples by XRD analysis as shown
below.
A slope of the SiO2–Al2O3 (Fig. 2B) and FeO–MgO (Fig. 2E)
correlations suggests their presence in high-Si mica (Electronic
Supplementary Table 2; Izraeli et al., 2004; Klein-BenDavid et al.,
2006). Phlogopite or other sheet silicates cannot be major constituents of the fluid as they do not plot on the observed compositional
trends (Fig. 2B). The CaO–SiO2 trend can be ascribed to mixing
between carbonates+apatite and high-Si mica (Fig. 2A). A strong
apatite trend of correlated CaO and P2O5 is evident in 18 out of 20
diamonds. Only samples 27 and 14 with the highest SiO2 content and
the lowest content of P2O5 do not show the apatite trend. It is absent
in the silicic part of the zoned diamond, but is strong in the outer
carbonatitic zone. Positive and variable intercepts of this trend with
the CaO axis (Fig. 2C) in different samples suggest that while apatite is
the main depository for P2O5, not all CaO is sequestered in apatite.
The composition of the carbonatitic component may be explained
by the presence of complex Ca–Mg–Fe carbonates (Fig. 2A, E) analyzed
from fluid inclusions in diamonds (Klein-BenDavid et al., 2006;
Logvinova et al., 2008) that also contain Na. It is suggested by a
broad negative correlation between Na2O and K2O, the absence of the
Na–Cl correlation and positive correlations of Na2O with MgO, and CaO
with MgO and FeO.
Mica is the principal daughter mineral of the silicic component,
and the most Si- and Al-rich inclusions consist entirely of the Si-rich
Cl-bearing mica. The silicic component therefore incorporates some
amounts of Fe, Mg, K, Cl, although the main budget for these oxides
are in other components and minerals. Correlations of BaO with K2O
and Cl and the detection of Ba mica kinoshitalite among daughter
minerals of the studied fluid (Section 6) suggest that Ba may be
residing in the silicic component in the high-Si mica. Our study did not
find Ba carbonates reported in fibrous diamonds elsewhere (Walmsey
diamond generation (Fig. 3b), are broken and resorbed
growth structure of diamond J9. The core zone of an
crystals (Fig. 3c) or display very complex growth patterns
octahedral/rounded shape likely formed in a regime of
RiMG Chapter 12 of “Carbon in Earth” (some original photos from Kopylova et al. (2010; Bulanova et al. 2010)
(Fig. 3d, e). For example, Fig. 3e shows the complex
oscillating growth and slight resorption, which is consistent
inclusions are uniform throughout multiple growth zones of fibrous
Fluids in diamonds
(silicic)
Si+Al
Si+Al
Ca
MgAPoorBYaku7an
Brazil
Diavik
MgARichBYaku7an
Koffiefontein
Panda
K+Na
K+Na
(saline)
Ca+Mg+Fe
Ca+Mg+Fe
(carbona77c)
Botswana
Fe
Mg
1
RiMG Chapter 12 of “Carbon in Earth” (original from Kopylova et al. (2010)
Diamonds, fO2, fluid speciation, P, T
RiMG Chapter 12 of “Carbon in Earth”
Carbon isotopic compostions of diamonds
main mantle-range
(fibrous diamonds, mid-ocean ridge basalts
carbonatites and kimberlites)
Peridotitic diamonds
(n = 1357)
Polycrystalline
from kimberlites
highest
value
lowest value
(n = 120)
Eclogitic
from Jericho, Slave Craton,
Canada (n=42)
Eclogitic diamonds
(n = 997)
-40
-35
-30
-25
-20
-15
-10
-5
0
-30
-25
-20
-15
-10
-5
0
-30
-25
-20
-15
-10
-5
0
Komatiitic
from Dachine
French Guyana
(n=181)
-40
Fibrous diamonds
and diamond coats
-35
Carbonados
(n = 127)
(n=54)
-40
Lower mantle diamonds
(n = 78)
-35
F) Metamorphic diamonds
(n = 120)
Jagersfontain
(South Africa)
Transition Zone
Sao Luiz
(Brazil)
Kankan
(Guinea)
-40
-35
-30
-25
-20
-15
-10
-5
0
-25
-20
-15
-10
-5
0
Recycled carbon
(n = 31)
-40
-35
-30
-25
-20
-15
-10
-5
0
-40
-35
-30
δ13C (‰)
RiMG Chapter 12 of “Carbon in Earth”
δ13C (‰)
diamonds with visible eclogitic inclusions over five sieve sizes
(Table 3). For Premier, a similar situation exists with the exception
Diamonds as characterized by their silicate inclusions
T. Stachel, J.W. Harris / Ore Geology Reviews 34 (2008) 5–32
Table 3
Relative abundance of the principal inclusion groups
studies)lithospheric
as a function
of diamond
size
Fig. 6. The relative abundance of various
diamond
sources
based on 2844
inclusion-bearing diamonds. “Unspecified” refers to peridotitic diamonds that contain
Sieve Class
−6 + 5
−7 + 6
−9 + 7
neither garnet nor clinopyroxene. The wehrlitic paragenesis (7 diamonds, 0.2%) is
Aperture [mm]
1.83
2.16
2.46
omitted from the diagram.
Finsch
Diamonds studied
Peridotitic [%]
Eclogitic [%]
Sulphides [%]
100 Ecl/(Ecl + Per)
Premier
Diamonds studied
and Harris
(2008)
Ore based
Geology
34, 5-32.
ig. 5. The relative abundance of diamondStachel
source regions
in the Earth's
mantle
on Reviews
Peridotitic
[%]
145 inclusion bearing diamonds. “Deep” stands for diamonds containing garnet with a
Eclogitic [%]
5929
83.7
2.8
13.5
3.2
841
74.0
7.7
18.2
9.5
432
63.3
6.9
29.9
9.8
1549
38.8
27.6
319
28.9
62.1
179
21.2
63.2
Diamonds and mantle geology
-1
depth = 150 km
-0.5
0
0.5
1
P-wave velocity anomaly (%)
16
18
M
20
O
22
LE
V
24
JW
P
26
Z
L
F
R
D
KO
K
28
P
2.5
JA
30
E-TYPE SILICATE
INCLUSIONS
0.9SILICATE
P-TYPE
INCLUSIONS
16
18
20
22
24
34
BORDER OF 2.5 Ga PERIDOTITES
2.5
14
32
26
28
30
Longitude East
RiMG Chapter 12 of “Carbon in Earth”
32
34
36
36
Latitude South
2.5
Geothermobarometry on mineral inclusions in diamonds
RiMG Chapter 12 of “Carbon in Earth”
Basaltic minerals at high pressure in the deep mantle
D
D
Downloaded from www.sciencemag.org on Nove
Downloaded from www.sciencemag.org on November 6, 2011
Downloaded from www.sciencemag.org on Nove
of
carbon.
theevidence,
above
hypothesis
is correct,
about
million
yearsassemblages,
old,
the
presented
here on
is compo
surface-derived
carbon
may
notonly
survive
into100clusions
Several
localities,
however,
yieldpetrologic
rare
“superdeep”
upward
by
of kilometers
in the
upper
t with surface-derived
wenoconclude
thatIf
the
deep
carbon
cycle
composite
and
has
been
direct
however,
of the
return
ofthen
subducted
oceanic
crustal
composite
assemblages,
and
these
are hundreds
interpreted
however,
of the
return
ofcarbon,
subducted
oceanic
crustal
esumably
by
upwelling
of inclusion
solid
slabs
into
the
mantle.
Seismological
studies
extend
thissublithospheric
process
to
the lower
mantle,
and1
phase
mineral
assemblage
(Fig.
thethe
lower
mantle.
Oceanic
lithosphere
clearly
diamonds
with
compositions
that which
remantle,
presumably
by
upwelling
of solid
wer
mantle.
the
carbon
diamonds
formed
ofJuina-5
aundated
inclusion
from
to matehave
formed
during
asc
components
from
the
lowerfrom
mantle.
analyzed
superdeep
diamonds
from
kimberlite,
toWehave
formed
during
ascent
in the
mantle
analyzed
superdeep
diamonds
from mateJuina-5
kimberlite,
13). For
example,
the
bulk
composigeochemical
indicate
of
oceanic
crust
thecomposiupper tomantle
in plumes
quire the
a sublithospheric
origin
in the
deep
upper
rialentire
(3, return
4,8,phase
13).
For
example,
the to
bulk
related
kimberlite
eruptio
Brazil,
which
host inclusions
with
compositions
comprising
the
assemblage
expected
related toobservations
kimberlite
eruption
(2–5,
12, 21,
22).
itions
comprising
entire
phase
assemblage
expected
mantle
even
the
lower
mantle
(1,
2).
plus
clinopyroxene
hasInclubeen
direct
petrologic
evidence,
however,
of
the
return
ofInclusion
subducted
oceanic
cru
of composite
plus
clinopyroxene
inclusions
have
previously
beennoidentified
with
dcomposite
the conditions.
mineralgarnet
inclusions
that
unmixing
provides
to
crystallize
from
basalt
under
lower-mantle
conditions.
Thetions
inclusion
mineralogies
require
Inclusion
unmixing
provides
compelling
evidencegarnet
ntle
The and
inclusion
mineralogies
require
sions
ofsamples
majorite
garnet
that
formed
in tothe
deep
that some
superdeep
exhumation
the isotope
lower
upper
mantle.
Because
the
diamond
hosts
have
carbon
isotope
inclusions
intransported
diamonds
from
the Juina
region
in-from
major
element
compositions
consistent
with
an
ing
growth
in diamonds
from
the
Juina
region
incomponents
from
the lower
mantle.
We
analyzed
superdeep
diamonds
Juina-5diamo
kim
that
some
superdeep
diamonds
were
ntle.
Becauseprovide
the
diamond
hosts
havefrom
carbon
upward
by hundreds
of kil
signatures
with surface-derived
wecarconclude
thatacompositions
theindeep
carbon
cycle
upper
mantle
(~200
toconsistent
500
commonly
have
dicate
deep
upper-mantle
origin asthe
majorite,
with
origin
inkm)
subducted
basalt.
Furthermore,
the
from
deepwewithin
Earth.
On
upward
by
hundreds
of kilometers
the
upper
dep
carbon,
conclude
that
the deep
carbon
cycle
upper-mantle
origin
as
majorite,
with
Brazil,
whichcarbon,
host
inclusions
with
comprising
entire
phase
assemblage
mantle,mineralogies
presumably byrequ
upw
intothem
the lower
mantle.
linking
to basaltic
oceanic
mantle,
presumably
upwelling
ofunmixing
solid mateinclusion
to garnet plus
clinopyroxene
bon
isotopic
compositions
of diamonds
withbyunder
mineralogy,
most
diamonds
unmixing
tocompositions
garnet
plusextends
clinopyroxene
to
crystallize
from basalt
lower-mantle
conditions.
The
inclusion
riallevels
(3, 4, have
13). For
exampl
(3, from
4, all
13).the
Forlower
example,
the bulk
composicrust
(1–8),
and aluminous
have
been
occurring
during
transport
lower-mantle
inclusions
arerial
typically
mantlece
originated
in continental
during
transport
to shallower
levelsinclusions
exhumation
to
upper
mantle.
Because to
theshallower
diamond
hosts
carbon
is
of composite garnet
inclusions
have
previously
been identified
with oftions
iamonds
and
the
mineral
inclusions
that
tions
of
composite
garnet
plus
clinopyroxene
inclusions
have
previously
been
identified
with
ns
that
identified
with
compositions
indicative
of
silibeneath
the
lithosphere
(2–4).
Each
the
inlike
(~
–4
to
–6‰)
(2),
which
suggests
that
at
depths
of
<200
km
(1).
he lithosphere (2–4). Each of the insignatures
consistent
withelement
surface-derived
carbon,
we conclude
that
the deep
carbon from
cyc
inclusions
in
diamonds
major
compositions
consistent
with
an
they
trap
during
growth
provide
samples
inclusions
in
diamonds
from
the
Juina
region
inmajor
element
compositions
consistent
with
an
mples
ceous
sediments (3).
The
diamonds that
host
these
clusions presented here is composed of a multicarbon
mayinto
not the
survive
into
wever,
yield
rare
resented
here
is“superdeep”
composed
ofsurface-derived
a
multiextends
lower
mantle.
dicate a deep upper-mantle o
origin in subducted
basalt.
Furthermore,
the1).
car-We interpret
of materials
from
deep
within
Earth.
On upper-mantle
dicate
a deep
originmineral
as majorite,
with
origin
in subducted
basalt.
Furthermore,
the
carth. On compositions
inclusions
carbon
isotopic
compositions
phase
assemblage
(Fig.
the
lower
mantle.
Oceanic
lithosphere
clearly
usion
thathave
re-We
eral
assemblage
(Fig.
1).
interpret
bon to
isotopic
compositions
of diamonds with inclusion unmixing to garn
the basis
of inclusion
mineralogy,
most
diamonds
inclusion
unmixing
garnet plus
clinopyroxene
isotopic
compositions
ofmantle
diamonds
monds
are
atypical
of normal
(d13Cwith
≈ –5‰),
ric originbon
inthat
the
deep
upper
inclusions
previously
been
identi
iamondsduring
andlower-mantle
the
mineral
inclusions
that
occurring
during
transpor
arelevels
typically
all mantle-have
sampleda large
at
surfaceallrange
originated
into
continental
occurring
transport
toinclusions
shallower
lower-mantle
inclusions
arethe
typically
mantlenental
lower mantle
(1, 2).
Incluinstead
displaying
isotopic
(~ −1
major element
compositions
consisten
they
growth
samples
the lithosphere
(2
like (~
–4(2–4).
toprovide
–6‰)
which
that beneath
lithospheric
mantle
at depths
of <200
km trap
(1).
beneath
the during
lithosphere
Each(2),
of the
in- suggests
like–24‰)
(~ in
–4the
to deep
–6‰)
which
suggests
that
m (1).
rnet
that formed
with
a clear(2),
tendency
toward
isotopically
clusions
presented
here is c
surface-derived
carbon
Several
localities,
however,
yield
clusions
presented
heredeep
is composed
of amay
multisurface-derived
carbon
may not
survive
intorare “superdeep”
rdeep”
origin ininto
subducted
basalt.
Furthermore
of materials
from
within
Earth.
Onnot survive
to 500 km)
commonly
have
“light” (< –10‰)
compositions
(1–3,
9).
Although
the lower mantle.
lithosphere clearly phase mineral assemblage
diamonds
with
inclusion clearly
compositions
that
re- assemblage
phase
mineral
(Fig. 1).Oceanic
We interpret
lower mantle.
Oceanic
lithosphere
hat
re- tothebasaltic
the basis
g them
there
is oceanic
debate regarding
the origin of
light
car- of inclusion mineralogy, most diamonds bon isotopic compositions of diamo
quire a sublithospheric originsampled
in the deep
upper
upper
minous inclusions
been (10), a leading hypothesis
bon inhave
diamonds
is at the surface originated in continental lower-mantle inclusions are typically al
mantle and even the lower mantle (1, 2). IncluInclumantle at depths of <200 km (1). like (~ –4 to –6‰) (2), which sugg
positions indicative
of sili- of the isotopically light lithospheric
the
subduction
organicin the deep
sions of majorite garnet that formed
e deep
Several localities, however, yield rare “superdeep” surface-derived carbon may not surv
The diamonds
that host
these
carbon
fraction
altered
oceanic
crust.
upperofmantle
(~200
to 500
km) commonly have
y have
bon isotopic compositions
with inclusion compositions that re- the lower mantle. Oceanic lithospher
The rarest
diamonds are
thosethem
containing
in- oceanic
compositions
linking
todiamonds
basaltic
ceanic
13
ormal
(d C ≈ with
–5‰),
compositions
indicatinginclusions
an
origin
quire
a have
sublithospheric
origin in the deep upper
crust
(1–8), and aluminous
been
e beenmantleclusions
large
(~ −1
to
inrange
the lower
mantle (>660
km). Inclusions
in-andofeven
mantle
lower mantle (1, 2). Incluidentified
with compositions
indicative
sili-1.the
of
sili-isotopic
Fig.
Backscattered
electron micrographs showing composite inclusions in diamonds f
isotopically
terpreted
as ceous
representing
the(3).
lower-mantle
phases
sions
of host
majorite
garnet
that
formed
in thecomposed
deep
sediments
The diamonds
that
these
tendency
these toward
An
inclusion
in
diamond
Ju5-20
of a mixture of spinel (Mg,Fe)Al2O4 (Sp)
mpositions
(1–3,
9). Although
Mg-perovskite
and Ca-perovskite
major
elinclusions
have carbonhave
isotopic
compositions
sitions
upper
mantle
(~200
to
500
km)
commonly
have
NaAlSiO4 (Ne) (fig. S1 and table S5), together with a small sulfide (Sf) in one corner that w
13
ding the origin
of light
car-are atypical
ement
compositions
that indicate
origin
in
that
of normalan
mantle
(d
C
≈
–5‰),
–5‰),
compositions
linking
themphase
to basaltic
oceanic
originally
distinct
from the
composite silicate; sulfide can participate in diamon
0),
a
leading
hypothesis
is
mantle peridotite
11–13).
No
lower-mantle
instead(2,
displaying
a
large
isotopic
range
(~
−1
to
−1 to
crust (1–8),
andmineralogy
aluminous
been oceanic
reactions
as a meltinclusions
phase
thathave
is immiscible
in silicatecrust
(33). as
(B) aAnfunction
inclusionof
in depth
diamoni
Fig. 3. (A) Estimated
modal
in
subducted
basaltic
e isotopically light organic
–24‰) with a clear tendency toward isotopically
pically
composed
of phases
with
the compositions
spinel
and aNAL,
nepheline-kalsilite
(Ka)stish
pha
identified
with
compositions
indicative
of sili- CF,ofCF
mantle
(17, 18).
MgPv,
Mg-perovskite;
CaPv,
Ca-perovskite;
phase;
NAL phase; St,
1
ltered oceanic
crust.
“light”
(<
–10‰)
compositions
(1–3,
9).
Although
hough
School of Earth Sciences, University of Bristol, Bristol BS8 1RJ,
(table(3).
S5).
(C) inclusion
An inclusion
inhost
diamond
Ju5-89
containing
spinel
and a mixture
of mM
ceous
sediments
The
diamonds
that
thesein
2
Gt,
garnet;dethe
Cpx,
clinopyroxene.
The
mineralogy
diamonds
from
Juina-5,
including
Instituto de
Geociências,
Universidade
Brasília,
CEP
there
is debate
regarding
origin
of light
carndscarare thoseUK.containing
inht
Na-rich
(Na) andisotopic
K-rich (K)compositions
silicate regions, with a bulk composition similar to Ju5-67 (f
3
inclusions
have
carbon
70910-900
Department
ofa Terrestrial
MagCaPv,
CF phase,
NAL
phase,
and
stishovite,
is
stable
atJu5-47
depths
ofconsists
~700 to
1400 km in the
lower
mantl(
bon DF,
in Brazil.
diamonds
(10),
leading
hypothesis
is
esis is indicating
ositions
an Brasília,
origin
13
S5).
(D)
An
inclusion
in
diamond
that
of
orthopyroxene
(Opx),
ulvospinel
Carnegie
Washington,
DC 20015,
that USA.
are
atypical
of normal
mantle
(dascent
C ≈ –5‰),
the
subduction
of the isotopically
light
organic
rganic
(>660 km).4netism,
Inclusions
in-Institution,
A
schematic
model
for
diamond
formation
and
the
Brazilian
lithosphere.
We ofsugges
(Ol)
(fig.
S3
and
table
S5).
(E)
Anbeneath
inclusion
in diamond
Ju5-43
that
consists
a com
Geophysical Laboratory,Fig.
Carnegie
Institution, Washington,
1.
Backscattered
electron
micrographs
showing
composite
inclusions
in
diamonds
from
Juina-5.
(A)
instead
displaying
a
large
isotopic
range
(~
−1
to
carbon
fraction
of
altered
oceanic
crust.
ting the lower-mantle
the diamonds
and Ju5-20
inclusions
initially
formed
subducted
oceanic
crustal
components
in the
u
orthopyroxene
a Ti-,from
Al-,spinel
and
Fe-rich
phase
similar
to tetragonal
almandine
pyrop
DC 20015, phases
USA.
An
inclusion
in diamond
composed
of aand
mixture
of
(Mg,Fe)Al
2O4 (Sp) and nepheline
–24‰)
with
a
clear
tendency
toward
isotopically
The
rarest
diamonds
are
those
containing
inng
inCa-perovskite
have
major
el- Juina-5.
(table
S5). (F)
Ana inclusion
in
Ju5-104
composed
CaSiO
micrometer-size
part
ofbe the
mantle
and
were
transported
indiamond
an in
upwelling
to ofthe
upper
where
*To
whom
correspondence
should
addressed.
E-mail:
nclusions
in
diamonds
from
(A)
NaAlSiO
(fig.lower
S1indicating
and
tablean
S5),
together
with
small sulfide
(Sf)
one
cornerplume
that we interpret
as 3anplusmantle,
4 (Ne)
clusions
with
compositions
origin
origin
“light”
(<
–10‰)
compositions
(1–3,
9).
Although
spinel
that (Mg,Fe)Al
indicate
an
origin
in
(e.g.,
CaTiO3silicate;
) and a sulfide
smalltosulfide
(table S5).in diamond
[email protected]
nepheline
originally
distinct
phase
from
theinclusions
composite
can
participate
crystallization
unmixed
into
composite
according
lower-pressure
phase relations.
2O4 (Sp)inand
ns
inthe
lower
mantle
(>660
km).
Inclusions
inthere
is
debate
regarding
the
origin
of
light
car,(Sf)
11–13).
No
lower-mantle
1. Backscattered
electron
showing
composite
inclusions
in1.diamonds
Juina-5.
(A)
Fig.
Backscattered
electron
micrographs
showing
composite
reactions
phase
that
is immiscible
in silicate
(33). from
(B) An
inclusion
in diamond
Ju5-67
that is inclusions in diam
in oneFig.
corner
that we
interpret
as micrographs
anas a melt
phases
terpreted
as
representing
the
lower-mantle
phases
Redrafted
from
Kohn, composed
Araujo,
Smith,
Gaillou,
Wang,
Steele,
and
(2011).
Science
334,(Mg,Fe)Al
54–57.2O
bon
in compositions
diamonds
a leading
hypothesis
is Shirey
An inclusion
in Walter,
diamond
Ju5-20
of
a mixture
of spinel(10),
(Mg,Fe)Al
O4 in
(Sp)
and nepheline
An
inclusion
Ju5-20
composed
of a(Na,K)AlSiO
mixture
of4 spinel
composed
ofCa-perovskite
phases Bulanova,
with
the
of
spinel
a diamond
nepheline-kalsilite
(Ka) phase,
2and
njorparticipate
in diamond
crystallization
elMg-perovskite
and
have
major
el7with
OCTOBER
2011
VOL
334
SCIENCE
University 54
ofNaAlSiO
Bristol, Bristol
BS8
1RJ,S1 and
the
ofJu5-89
the
isotopically
light
organic
(fig.
table
S5),
together
asubduction
small
sulfide
(Sf)
inNaAlSiO
one
corner
that
we
interpret
asawww.sciencemag.org
an
(fig.
S1
and
table
S5),
together
with a small sulfide (Sf) in one corner
4 (Ne)
4 (Ne)
(table
An inclusion
in diamond
containing
spinel
and
mixture
of micrometer-sized
An inclusion
in diamond
Ju5-67
thatS5).
is (C)
the diamonds formed
of a dated sublithospheric inclusion from the
Diamond capture and inclusion unmixing
Fig. 4. Carbon is
this study compar
White rectangles
each diamond on
ments in different
luminescence ima
of several possibl
dal mineralogy in subducted basaltic oceanic crust as a function of depth in the matically on the b
carbon denotes ei
g-perovskite;
CaPv,
Ca-perovskite;
CF,Smith,
CF phase;
phase;
St, stishovite;
Walter,
Kohn,
Araujo, Bulanova,
Gaillou, NAL,
Wang,NAL
Steele,
and Shirey
(2011). Science 334, 54–57.
oxene. The inclusion mineralogy in diamonds from Juina-5, including MgPv, bonate carbon or
Craton Formation and Modification
~ 2 - 3.5 Ga
amalgamated cratonic lithosphere
~ EMOG
diamond precipitation
via redox freezing
650
elting
m
us?)
(hydro
t
s
u
r
c
onated
of carb
stranding and ‘themalization’ of slab
RiMG Chapter 12 of “Carbon in Earth”
-5
inclusions crystallized
from melts
re
he
p
s
o
su
d
te
c
u
bd
h
lit
d
on
n
io
t
a
rm
in
b?
a
sl
ΔFMQ
450
inclusion unmixing
redox crystallization from primordial
and recycled fluids and melts rich in
CH4, H2O, CO3-, CO2, S, Cl, etc
sub-lithospheric mantle
250
-4
cratonic root
uplift (plume?)
E-type
gr
ap
hi
di
te
am
on
d
redox melting
and freezing
-3
P-type
diamond resporbtion/ growth
250
Fe-Ni
metel/carbide
-2
ΔFMQ
150
accreted
lithosphere
metasomatism
kilometers
50
kilometers
crust
Diamond formation, deep to shallow
fo
am
di
Fe-Ni
metel/carbide
<-5