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 232

test of PGE was carried out maintaining GP-13 international standard (spinel
lherzolite). Comparison of results of PGE determination by this standard with its
passport data [Pearson & Woodland, 2000; Meisel & Moser, 2004] showed good
convergence.
In addition to the rocks of the massifs described above, determination of REE and
PGE by ICP-MS method was performed on samples from Bulkinsky massif, which is
located in the extreme north-eastern part of Tuva (Ergak-Targak-Tayga ridge, West
Sayan) and is structurally confined to junction of Kurtushibinsky and North-Sayan
ophiolite belts [Mongush et al ., 2005]. Its elliptical body is exposing an area of about
100 sq · km. with the long axis oriented to the submeridional direction. The massif
lies among terrigenous Upper Cambrian and Ordovician deposits and is composed
of gabbro-anorthosites, anorthosites, gabbros, gabbro-norites and troctolites, among
which stripe-like isolations of olivinites, olivine pyroxenites and hornblendites occur.
Quantitative-mineral composition of rocks from this and from other massifs, in which
REE contents were determined by ICP-MS method, is shown in the Table 10.3.

Table 10.3 Modal mineral compositions of ultramafic and mafic rocks from some massifs from Central
and East Tuva (Russia).

Samples Rocks Mineral composition, %

Mazhaliksky massif

30-1 Gabbro leucocratic with Hornb Cpx (17), Pl (80), Horb (3)

30-6 Olivine gabbro Ol (11), Cpx (45), Pl (50), Mt (4)

35-4 Wehrlite Pl-bearing with Hornb Ol (50), Cpx (40), Pl (4), Horb (6)

Karaossky massif

M-27-98 Websterite Pl-bearing Opx (36), Cpx (60), Pl (4)

M-29-98 Gabbro-norite Opx (10), Cpx (40), Pl (50)

M-30-98 Wehrlite with Opx Ol (85), Opx (3), Cpx (12)

Kalbagdagsky massif

9-3 Gabbro olivine-bearing with Hornb Ol (20), Cpx (45), Pl (34), Horb (1)

1-2 Gabbro-norite Cpx (35), Opx (15), Pl (50)

2-5 Clinopyroxenite olivine-bearing

with Hornb

Ol (8), Cpx (80), Pl (4), Horb (8)

Maysky massif

2150 Gabbro-norite Cpx (30), Opx (15), Pl (55)

2530 Gabbro olivine-bearing, leucocratic

with Hornb

Ol (20), Cpx (8), Pl (70), Horb (2)

2530-1 Gabbro olivine-bearing, mesocratic

with Opx

Ol (40), Opx (4), Cpx (10), Pl (45),
Mt (1)

Bulkinsky massif

Bl-4 Gabbro olivine-bearing, leucocratic

with Hornb

Ol (10), Cpx (15), Pl (70), Horb (4),
Mt (1)

Bl-7 Troctolite leucocratic with Cpx, Opx,
and Hornb

Ol (20), Opx (3), Cpx (1), Pl (70),
Horb (5), Mt (1)

Bl-17 Gabbro-anorthosite with Ol, Cpx, Opx,
and Hornb

Ol (2), Opx (2), Cpx (2), Pl (80),
Horb (10), Mt (1)

Note: Ol - olivine, Opx - orthopyroxene, Cpx - clinopyroxene, Pl - plagioclase, Hornb - hornblende, Mt - magnetite.