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Khayalygsky massif
Birdagsky massif
Birdagsky massif
Yb, ppm
Yb, ppm
Yb, ppm
Khayalygsky massif
Hornblendite
Melanocratic olivine gabbro-norite
Olivine clinopyroxenite
Lherzolite Pl-bearing
Hornblende gabbro
Yb, ppm
Figure 10.10
Relationships between Yb compositions and Pd/Ir (1 and 3) and Pt/Ir (2 and 4) parame-
ters values for Pl-bearing lherzolite, olivine clinopyroxenite, melanocratic olivine gabbro-
norite, hornblende gabbro and hornblendite from Birdagsky (1, 2) and Khayalygsky (3, 4)
massifs (West Tuva, Russia) (data Table 10.5).
The chondrite-normalized patterns of PGE and Re contents in the rocks of
Birdagsky and Khayalygsky massifs are similar in configuration and have a common
positive slope (Figure 10.9). At the same time some of the patterns are complicated
by minima for Ir and Pt, and minima for Ir in the patterns of rocks from Khayalygsky
massifs have a slightly greater intensity than in the other cases. The values of Pd/Pt
parameter in rocks from both of these massifs vary in a narrow range compared
with the values of Pd/Ir and Pt/Ir parameters. In the rocks of Birdagsky massif the
relationship between the values of Pd/Ir and Pt/Ir parameters, on the one hand,
and Yb contents, on the other hand, has not been ascertained, while in the rocks of
Khayalygsky massif an inverse relationship between these characteristics should not
be excluded (Figure 10.10).
Based on data on the relations between REE and PGE in rocks, the mafic-ultramafic
massifs of Tuva can be divided into three types: 1) massifs of rocks that are relatively
enriched with REE, but significantly depleted by PGE; 2) massifs of rocks that are
relatively depleted by REE and relatively enriched with PGE; 3) massifs of rocks that
are characterized by low concentrations of both REE and PGE. An inverse relation-
ship between the contents of REE and PGE occurs primarily in the rocks of the first
two types of massifs.
The above material on geochemistry of REE and PGE in rocks of mafic-ultramafic
massifs located in the territory of Tuva, with some exceptions, generally does not con-
tradict the assumption of the existence of a sort of antagonism between these two
groups of elements in different products of mafic-ultramafic magmatism.
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