European Geosciences Union General Assembly 2015 - Garnet Classification
Evolution of metasomatic agent for Group III-V
To explain evolution of REE composition form sinusoidal"
to "normal" patterns we used the model of melt injection
and percolation through a refractory mantle column
[Nimis et al., 2009; Ziberna et al., 2013]:
In this model, the melt progressively changes its
composition owing to chromatographic ion exchange,
fractional crystallization and assimilation of peridotitic.
minerals, under decreasing melt/rock ratios
100
(c)
1 cell, Grt Z4-3 (group B)
100
10
10
Gar/ C1 (Sun & McDonough, 1989)
10
0.01
100
Gar/ C1 (Sun & McDonough, 1989)
0.1
EUROPEAN
GEOSCIENCES UN
General Assembly 2015
Group V garnet
La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
IV
CC
Grt/CI
O
10
14th cell
Grt Z4-8 (group C)
0.01
Grt 25-14 (group C)
Grt in the ambient peridotite
(from Grt Z4-11)
0.001
La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Ziberna et al., 2013:
Plate model numerical simulation
Ο
BY
At a distance from the
region of kimberlitic melt
generated the peridotite
garnet has C1-normalized
"sinusoidal" REE patterns;
In the proximity to the
region of kimberlitic melt
generated garnet has C1-
normalized REE patterns
close to megacrysts.
[email protected]
Gar/ C1 (Sun & McDonough, 1989)
0.01
100
10
20
TTTTTTT
T
Group IV garnet
T
La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
III
H
0.1
Group III garnet
0.01
La Ce Pr Nd Pm Sm Eu Gd Tb
Ho Er Tm Yb Lu
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