first data for deep seated xenoliths and mantle geotherm
DESCRIPTION
First data for deep seated xenoliths and mantle geotherm of Zarnitsa kimberlite pipe, Daldyn , Yakutia . Igor Ashchepkov (1), 1), Nikolai Pokhilenko (1), Nikolai Vladykin (2), Zdislav Spetsius (3), - PowerPoint PPT PresentationTRANSCRIPT
First data for deep seated xenoliths and mantle geotherm of Zarnitsa kimberlite pipe, Daldyn, Yakutia.
Igor Ashchepkov (1), 1), Nikolai Pokhilenko (1), Nikolai Vladykin (2), Zdislav Spetsius (3), Alla Logvinova (1), Stanislav Palessky (1), Olga Khmelnikova (1), and Gleb Shmarov (3)
Sobolev Institute of Geology and Mineralogy SD RAS, Koptyug ave 3, Novosibirsk, Russia (1)Institute of Geochemistry SB RAS, Irkutsk Russia, (2), ALROSA Stock company, Russia (3)
First discovered in Yakutia and the largest in Daldyn region kimberlite pipe is composed from several phases including breccias and porphyric kimberlites. Commonly mantle xenolith from this pipe especially included in the prevailing grey breccia are nearly completely altered. Only relatively fresh material from the brownish – grey breccia from the drilling core and porphyric kimberlites includes material which could be used for the mineral thermobarometry. The picroilmenites from the Zarnitsa pipe are forming three clusters according to the Cr- content: 0.5; 1.0 and 2.5 % Cr2O3 (Ashchepkov,Amshinsky, Pokhilenko, 1980; Amshinsky, Pokhilenko,1984; Alymova et al., 2003) due to the different contamination degree of protokimberlites in mantle peridotites. The ilmenites from porphyric kimberlites are forming stepped trend consisting from three groups of different pressure intervals from 6.5 to 4.0 GPa but more continuous than those determined for the ilmenites from breccia (Ashchepkov et al ., 2010). The relatively low Cr diopsides are corresponding to the deeper part while those containing to 2 -3 of Cr2O3 are from the middle part of the mantle section and are in association with the phlogopites contain the reflecting processes of the protokimbelite differentiation and contamination. Peridotites from the lithosphere base are of Hi temperature type and slightly Fe - enriched and are referred to the porphyroclustic types where garnets contain up to 10% Cr2O3 are they are relatively low in TiO2. But there are alos varieties of reduced Cr and the Fe-enriched which are closer to the deformed type (Agashev et al., 2013). The cold clot in the 60-5.5 GPa (34 mwm-2) are represented by Fe- low peridotites with the garnets of sub-Ca types. The Cr- low and LT eclogites are correspondent to the low 4.5-6.0 GPa interval similar to those from Udachnaya pipe. But near the pyroxenites lens the varieties enriched in Fe and sometimes hybrid pyroxenites appear like in most pf mantle sections in Yakutia. In general the Fe# of the garnets beneath Zarnitsa pipe reveal essential increase which became more pronounced in the uppermost part of the SCLM. the basic cumulates and Phl -Ilm bearing Gar pyroxenites are detected near the Moho boundary. The Gar - Px mantle geotherm in Zarnitsa SCLM is relatively cold. But the heating coinciding with the appearance of Ilm- pyroxenites and basic cumulates in the uppermost part of lithosphere were determined. The trace elements for the mantle peridotites from the common un - enriched type show the peak in Pb, U for both Cpx and garnet probably marking post - subduction origion bu the enriched type reveal HFSE and Sr rise due to metasomatism. 11-05-00060; 11-05-91060-PICS and joint research projects of IGM SB RAS and ALROSA Stock company 77-2, 65-03, 02-05.
Garnets
Spinels
Amphiboles
Ilmenites
Clinopyroxenes
Zarnitsa all tohether Zarnitsa xenolith only
TRE formantle peridotites
0.05 0.10 0.15 0.20 0.25600 800 1000 1200 1400
Fe# Ol in equilibrium with Cpx, Opx, Gar, Chr, Ilm
0.0 4.0 8.0 -6.0 -4.0 -2.0 0.0
SEA
T oCZ arn itsa
45 m w /m 2
35 m w /m 2
Sp
Gr
40 m w /m 2
Diamond
Graphite
1. CaO in Gar2. Al2O 3 in Opx3. Cr2O3 in Cpx4. TiO 2 in Chr5. Cr2O3 in Ilm
8
7
6
5
4
3
2
1
0
P(G
Pa)
8
7
6
5
4
3
2
1
P(GPa) 8
7
6
5
4
3
2
1
P(GPa) 8
7
6
5
4
3
2
1
0-LogFO 2Variation of
Cpx, Opx, Gar, Chr, Ilm
Xenoliths G arnet PT estim ates (Ashchepkov, 2006)C px (Ashchepkov, 2010)Eclogites (Ashchepkov, 2010)O px (Brey, Kohler,1990-M cG regor, 1974) G ar- O px (Brey, Kohler,1990)
0.05 0.10 0.15 0.20 0.25600 800 1000 1200 1400
Fe# Ol in equilibrium with Cpx, Opx, Gar, Chr, Ilm
0.0 4.0 8.0 -6.0 -4.0 -2.0 0.0
SEA
T oCZ a rn itsa xen o lith s
45 m w/m 2
35 m w /m 2
Sp
Gr
40 m w/m 2
Diamond
Graphite
1. CaO in Gar2. Al2O 3 in Opx3. Cr2O3 in Cpx4. TiO 2 in Chr5. Cr2O3 in Ilm
8
7
6
5
4
3
2
1
0
P(GPa) 8
7
6
5
4
3
2
1
P(GPa) 8
7
6
5
4
3
2
1
P(GPa) 8
7
6
5
4
3
2
1
0-LogFO 2Variation of
Cpx, Opx, Gar, Chr, Ilm
0.05 0.10 0.15 0.20 0.25600 800 1000 1200 1400
Fe# Ol in equilibrium with Cpx, Opx, Gar, Chr, Ilm
0.0 4.0 8.0 -6.0 -4.0 -2.0 0.0
SEA
T oCN ev id im k a
45 m w /m 2
35 m w /m 2
Sp
Gr
40 m w /m 2
Diamond
Graphite
1. CaO in Gar2. Al2O 3 in Opx3. Cr2O3 in Cpx4. TiO 2 in Chr5. Cr2O3 in Ilm
8
7
6
5
4
3
2
1
0
P(GPa) 8
7
6
5
4
3
2
1
P(GPa) 8
7
6
5
4
3
2
1
P(GPa) 8
7
6
5
4
3
2
1
0-LogFO 2Variation of
Cpx, Opx, Gar, Chr, Ilm
0.05 0.10 0.15 0.20 0.25600 800 1000 1200 1400
Fe# Ol in equilibrium with Cpx, Opx, Gar, Chr, Ilm
0.0 4.0 8.0 -6.0 -4.0 -2.0 0.0
SEA
T oCM alyu tk a
45 m w /m 2
35 m w /m 2
Sp
Gr
40 m w /m 2
Diamond
Graphite
1. CaO in Gar2. Al2O3 in Opx3. Cr2O3 in Cpx4. TiO 2 in Chr5. Cr2O3 in Ilm
8
7
6
5
4
3
2
1
0
P(GPa) 8
7
6
5
4
3
2
1
P(GPa) 8
7
6
5
4
3
2
1
P(GPa) 8
7
6
5
4
3
2
1
0-LogFO 2Variation of
Cpx, Opx, Gar, Chr, Ilm
0.05 0.10 0.15 0.20
Fe# O l in equilibrium with Cpx, Opx, Gar, Chr, Ilm
600 800 1000 1200 1400 0.0 4.0 8.0
Variation of Cpx, Opx, Gar, Chr, Ilm
-6.0 -4.0 -2.0 0.0
-LogFO 2
SEA
T oC
GraphiteDiamond
D a ln y a y a
45 m w /m 2
35 m w /m 2
Sp
Gr
40 m w /m 2
1. CaO in Gar2. Al2O 3 in Opx3. Cr2O 3 in Cpx4. TiO 2 in Chr5. Cr2O 3 in Ilm
8
7
6
5
4
3
2
1
0
P(G
Pa)
8
7
6
5
4
3
2
1
P(G
Pa)
8
7
6
5
4
3
2
1
P(G
Pa)
8
7
6
5
4
3
2
1
0
P(G
Pa)
AOpxG
0.95 0.90 0.85 0.80Mg' Ol in equilibrium
with Cpx, Opx, Gar, Chr, Ilm
0.05 0.10 0.15 0.20
Fe# O l in equilibrium with Cpx, Opx, Gar, Chr, Ilm
600 800 1000 1200 1400 0.0 4.0 8.0
Variation of Cpx, Opx, Gar, Chr, Ilm
-6.0 -4.0 -2.0 0.0
-LogFO 2
SEA
T oC
GraphiteDiamond
F estiv a ln aya
45 m w /m 2
35 m w/m 2
Sp
Gr
40 m w /m 2
1. CaO in Gar2. Al2O 3 in Opx3. Cr2O 3 in Cpx4. TiO 2 in Chr5. Cr2O 3 in Ilm
8
7
6
5
4
3
2
1
0
P(G
Pa)
8
7
6
5
4
3
2
1
P(G
Pa)
8
7
6
5
4
3
2
1
P(G
Pa)
8
7
6
5
4
3
2
1
0
P(G
Pa)
AOpxG
0.95 0.90 0.85 0.80Mg' Ol in equilibrium
with Cpx, Opx, Gar, Chr, Ilm
0.05 0.10 0.15 0.20
Fe# Ol in equilibrium with Cpx, Opx, Gar, Chr, Ilm
600 800 1000 1200 1400 0.0 4.0 8.0
Variation of Cpx, Opx, Gar, Chr, Ilm
-6.0 -4.0 -2.0 0.0
-LogFO 2
SEA
T oC
GraphiteDiamond
O sen n ya ya
45 m w /m 2
35 m w /m 2
Sp
Gr
40 m w /m 2
1. CaO in Gar2. Al2O3 in Opx3. Cr2O3 in Cpx4. TiO 2 in Chr5. Cr2O3 in Ilm
8
7
6
5
4
3
2
1
0
P(G
Pa)
8
7
6
5
4
3
2
1
P(G
Pa)
8
7
6
5
4
3
2
1
P(G
Pa)
8
7
6
5
4
3
2
1
0
P(G
Pa)
AOpxG
0.95 0.90 0.85 0.80Mg' Ol in equilibrium
with Cpx, Opx, Gar, Chr, Ilm
0.05 0.10 0.15 0.20
Fe# O l in equilibrium with Cpx, Opx, Gar, Chr, Ilm
600 800 1000 1200 1400 0.0 4.0 8.0
Variation of Cpx, Opx, Gar, Chr, Ilm
-6.0 -4.0 -2.0 0.0
-LogFO 2
SEA
T oC
GraphiteDiamond
L etn ya ya
45 m w/m 2
35 m w/m 2
Sp
Gr
40 m w/m 2
1. CaO in G ar2. Al2O3 in Opx3. Cr2O3 in Cpx4. TiO2 in Chr5. Cr2O3 in Ilm
8
7
6
5
4
3
2
1
0
P(G
Pa)
8
7
6
5
4
3
2
1
P(G
Pa)
8
7
6
5
4
3
2
1
P(G
Pa)
8
7
6
5
4
3
2
1
0
P(G
Pa)
AOpxG
0.95 0.90 0.85 0.80Mg' Ol in equilibrium
with Cpx, Opx, Gar, Chr, Ilm
Satellites located nearby
Z a rn itsa
40 44 48 52T iO 2 %
0.0
0.4
0.8
1.2 A l2 O 3 %
40 44 48 52T iO 2 %
0.0
1.0
2.0
3.0
4.0C r2 O 3 %
30.0
40.0
50.0
60.0 T i O 2 %
0 4 8 12 16 20M gO %
0 % F e2 O 3
20 % F e2O 3
40 % F e2 O 3
40 44 48 52T iO 2 %
25.0
30.0
35.0
40.0
45.0
50.0F eO %
40 44 48 52T iO 2 %
0.0
0.1
0.2
0.3 N iO %
40 44 48 52T iO 2 %
0.0
0.2
0.4
0.6
0.8V 2 O 5 %
BrecciaPorphyric kimberlitexenoliths
2 4 6FeO %
0
1
2
3
4
5
Cr 2
O3
%
2 4 6FeO %
0
0.2
0.4
0.6
0.8
1
TiO
2 %
2 4 6
2
4
6
Na 2
O %
2 4 6
4
8
12
Al 2
O3
%
8 16MgO %
2
4
6
8
10
Na 2
O %
ConcentrateXenolithsEclogites
0 2 4 6 8 10 12Cr2O3
0
4
8
12
CaO
0 2 4 6 8 10 12 14Cr2O3
0
4
8
12
16
20
FeO
0 2 4 6 8 10 12 14Cr2O3
0
0.4
0.8
1.2
1.6
2
TiO2
0 2 4 6 8 10 12 14Cr2O3
8
12
16
20
24
MgO
0 2 4 6 8 10 12 14Cr2O3
0
0.05
0.1
0.15
0.2
0.25
Na2O
0 2 4 6 8 10 12Cr2O3
0
0.2
0.4
0.6
0.8
NiO
Z a rn itsa
Concentrate brecciaConcentrate porphyric kim berliteXenoliths
Satellites distant Large pipes in Daldyn field
6 8Si (f.u.)
0
0.1
0.2
0.3
0.4
Cr (
f.u.)
6 8Si (f.u.)
0
0.05
0.1
0.15
0.2
0.25
Ti (f
.u.)
6 8
0.01
0.02
0.03
Mn
(f.u.
)
6 8
1
2
3
Al (
f.u.)
1. Sytykan2. Yubileinaya3. Komsom olskaya4. Zarnitsa
6 80.4
0.8
1.2
1.6
2
Ca
(f.u.
)
0.5 0.6K2O%
0.6
0.8
1
1.2
1.4
1.6
1.8
Na
(f.u.
)
6 8FeO %
0.2
0.4
0.6
0.8
K (f
.u.)
6 8Si
1
1.2
1.4
1.6
1.8
2
2.2
K+N
a (f.
u.)
Parg
asite
Parg
asite
hor
blen
de
Hor
blen
de
Ric
hter
ite
Parg
asite
Hor
blen
de
Ric
hter
ite
Parg
asite
hor
blen
de
6 80.2
0.3
0.4
0.5
0.6
Fe (f
.u.)
6 83.2
3.6
4
4.4
4.8
5.2
Mg
(f.u.
)
2 4 6 8FeO %
0
1
2
3
Cr 2
O3
%
2 4 6 8FeO %
0
2
4
6
TiO
2 %
2 4 6 8
16
20
24
28
32
MgO
%
2 4 6 810
12
14
16
Al 2
O3
%
2 4 6 8
0.2
0.4
0.6
0.8
1
Na 2
O %
2 4 6 8FeO %
32
36
40
44
48
SiO
2 %
1. Concentrate2. Peridotite xenoliths
PhlogopitesLa Pr Eu Tb Ho Tm Lu
0.10
1.00
10.00
100.00
1000.00
Sam
ple/
C1
La Pr Eu Tb Ho Tm Lu
0.10
1.00
10.00
100.00
Sam
ple/
C1
Rb Th Nb La Pb Nd Sm Zr Gd Ho Er Lu
0.01
0.10
1.00
10.00
100.00
Sam
ple/
PM
Rb Th Nb La Pb Nd Sm Zr Gd Ho Er Lu
0.01
0.10
1.00
10.00
100.00
1000.00
Sam
ple/
PM
Ce Nd Sm Gd Dy Er Yb
Ce Nd Sm Gd Dy Er Yb
Cs Ba U Ta Ce Pr Sr Hf Eu Dy Y Yb
Cs Ba U Ta Ce Pr Sr Hf Eu Dy Y Yb
A.
Б.
1 . 2 . 3 .4 .
1 . 2 .
Clinopyroxene
Garnets
Ilmenites
Chrom ites
1 .
1 . 2 .3 .4 .5 .
0 20 40 60Cr2O3
0
2
4
6
TiO 2
0 20 40 60Cr2O3
10
20
30
40
50
60
FeO
0 20 40 60Cr2O3
0
20
40
60
Al2O3
0 20 40 60Cr2O3
0
0.2
0.4
0.6
0.8
MnO
0 20 40 60Cr2O3
0
0.05
0.1
0.15
0.2
0.25
0.3
NiO
0 20 40 60Cr2O3
0.1
0.2
0.3
0.4
0.5
0.6
V2O 5
0 20 40 60Cr2O3
4
8
12
16
20
MgO
ConcentrateXenoliths
600 800 1000 1200 1400
600 800 1000 1200 1400
SEA
T oC
GraphiteDiamond
D aln ya ya
45 m w /m 2
35 m w /m 2
Sp
Gr
40 m w /m 2
8
7
6
5
4
3
2
1
0
P(G
Pa)
8
7
6
5
4
3
2
1
P(G
Pa)
AOpxG
T oC
8
7
6
5
4
3
2
1
P(G
Pa)
Z arn itsa
8
7
6
5
4
3
2
1
P(G
Pa)
600 800 1000 1200 1400
SEA
T oC
GraphiteDiamond
U d a ch n aya
45 m w /m 2
35 m w /m 2
Sp
Gr
40 m w /m 2
1. OpxMc742. Cpx As103. Cpx NT004. Gar As105. Chr As106. Ilm As7. BrKo90
8
7
6
5
4
3
2
1
P(G
Pa)
8
7
6
5
4
3
2
1
P(G
Pa)
600 800 1000 1200 1400
SEA
T oC
S y ty k a n sk a y a
45 m w /m 2
35 m w /m 2
Sp
Gr
40 m w /m 2
Diam ond
Graphite
8
7
6
5
4
3
2
1
0
P(GPa) 8
7
6
5
4
3
2
1AFG
Opx Geotherms