Geochemical relationship between REE and PGE in mafic and ultramafic rocks and their petrogenetic significance - Rare Earth Elements in Ultramafic and Mafic Rocks and their Minerals - page 233

Judging by the results of the analysis, in the rocks of the studied massifs the
total REE contents ranged from 3.5 to 75 ppm (Table 10.4). And the maximum total
REE contents were determined in samples from Maysky massif, the lower ones - in
the rocks from Mazhalyksky, Kalbagdagsky, Karaossky and Bulkinsky massifs.
The rocks of Maysky and Bulkinsky massifs are characterized by high LREE content
and the resulting relatively high values of (La/Yb) n parameter (Figure 10.3). The REE
distribution patterns of clinopyroxene and olivine gabbro-norite of Kalbagdagsky
massif have similar configuration, which indicates their depletion by LREE and
some enrichment with MREE. The REE distribution pattern of olivine gabbro of
the massif also indicates its enrichment with LREE. A distinctive feature of the rocks
from Kalbagdagsky massif is the lack of positive Eu anomalies in their patterns,

Table 10.4 REE (ppm), and PGE (ppb) compositions of ultramafic and mafic rocks from some massifs
from Central and East Tuva (Russia), ICP-MS.

Massifs

Kalbagdagsky Mazhalyksky Karaossky

1-2 9-3 2-5 30-1 30-6 35-4 M-29-98

Clinopyro-
xenite
olivine-
bearing

Gabbro-
norite

Olivine
gabbro

Olivine
gabbro

Gabbro-
norite Element Gabbro Wehrlite

Pd 7,60 8,77 5,69 3,28 3,74 8,51 N.d.

Pt 25,4 25,7 9,27 18,4 7,52 2,65 8,39

Ru 4,23 2,09 5,03 1,74 0,75 3,76 3,95

Ir 0,097 0,046 0,067 0,29 0,029 N.d. 0,19

Total 37,3 37,0 20,1 23,7 12,0 14,9 12,5

Pt/Ir 262 558 138 63 252 N.d. 44

Pd/Ir 78,4 191 84,9 7,86 129 N.d. N.d.

La 0,729 1,11 0,742 2,88 1,99 1,84 2,89

Ce 2,05 2,42 2,06 6,15 4,94 4,83 5,71

Pr N.d. N.d. N.d. N.d. N.d. N.d. N.d.

Nd 2,05 1,81 2,07 3,89 3,98 4,24 3,62

Sm 0,772 0,581 0,737 0,900 1,16 1,19 0,872

Eu 0,312 0,244 0,305 0,463 0,430 0,415 0,448

Gd 1,07 0,724 1,06 0,984 1,21 1,34 0,872

Tb 0,195 0,143 0,196 0,168 0,207 0,236 0,143

Dy 1,32 0,941 1,31 0,979 1,30 1,47 0,863

Ho 0,276 0,198 0,270 0,195 0,254 0,288 0,172

Er 0,748 0,586 0,776 0,542 0,679 0,778 0,462

Tm 0,114 0,088 0,113 0,084 0,099 0,109 0,076

Yb 0,715 0,498 0,747 0,474 0,576 0,686 0,439

Lu 0,100 0,074 0,098 0,068 0,078 0,092 0,067

(La/Yb) n 0,69 1,51 0,67 4,11 2,34 1,81 4,45

(Eu/Eu*) n 1,05 1,15 1,05 1,50 1,10 1,00 1,55

( Continued )