Environmental Engineering Reference
In-Depth Information
45
OIB source
40
35
30
25
20
Continental crust
15
10
Gd: Cy50
Gd: 4270/13
Mr: OM24
5
0
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
Cl/K
2
O
Figure 10.5 Composition of melt inclusions in olivine from the Gudchikhinsky
suite
(Cy50 and 4270/13)
and clinopyroxene
from the Maslovskoe
intrusion (OM24).
inclusions. Nevertheless, the minimum CO
2
contents in parental melt can be
estimated if inclusions of dense CO
2
fluid are associated with the inclusions. Such
estimates for alkaline lavas from Ayan River yield 1.5
-
2.0 wt% CO
2
(Ryabchikov
et al
.,
2001b
), which corresponds to 2.0
2.5 wt% CO
2
predicted from the Nd
contents of these melts (Ryabchikov
et al
.,
2001a
; Cartigny
et al
.,
2008
).
-
10.2.7 Sources of magmatic volatiles
Presented data and published results suggest a dramatic change in the Cl/K ratio
of the mantle source of magmas of the Norilsk section. Considering only crustal
uncontaminated magmas, the highest Cl/K ratio is found in the Gudchikhinsky
melt inclusions from the lowest part of the Norilsk section. The younger Ayan
River picrites, corresponding to the middle part of the Norilsk section and latest in
the sequence lavas from the Maymecha
Kotuy province (Delkansky picrites and
meimechites), display three times lower Cl/K ratios.
Based on Ni access over Mg, and Mn depletion over Fe of olivine, Sobolev
et al
.(
2009a
) suggested that the source of Gudchikhinsky picrites is almost pure
olivine-free pyroxenite produced by reaction of melted recycled oceanic crust and
-