Apatites - Rare Earth Elements in Ultramafic and Mafic Rocks and their Minerals - page 185

Thus, the observations show that variations of the REE composition of apatites
significantly correlate with petrographic belonging and formation conditions of rocks
containing them. Hallmarks of the overwhelming majority of the investigated apatites
are, firstly, more or less significant predominance of chondrite-normalized LREE
contents over the HREE, and, secondly, the presence on their REE patterns of nega-
tive Eu anomalies of various intensity. In addition, these results suggest that in-depth
study of REE distribution in apatites from rocks that form separate magmatic massifs
allows using such data to specify the taxonomy of rocks within these massifs, as well
as to ascertain the postmagmatic transformations of apatite-bearing rocks. Therefore,
a further detailed research of REE composition of apatites from rocks of different
composition and origin is an urgent task.

5.2 THE COEFFICIENTS OF REE DISTRIBUTION
BETWEEN APATITE AND MELTS AS WELL AS
COEXISTING PEROVSKITES

Among the first the estimates of K d (apatite/melt) values were obtained by the exam-
ple of samples from the natural system - basanites [Irving & Frey, 1984], and later
on - based on the results of experimental studies of basaltic melts [Ozawa & Shimizu,
1995] (Table 5.5). These observations showed that all the REE have values of K d
(apatite/melt) > 1. In addition, for the values of basanitic melts the values of K d (La, Ce)

Table 5.5 The coefficients of REE distribution between apatites and basanitic,
and basaltic melts.

Basanitic melt Basaltic melt

Nature system Experimental system

[Irving, Frey, 1984] [Ozawa, Shimizu, 1995]

Element IrF-1(min) IrF-1(max) OZ-1

La 8,8 20,0 3,3

Ce 10,0 21,0 4,0

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

Nd N.d. 12,0 7,7

Sm 12,0 16,0 7,7

Eu 12,0 15,0 6,4

Gd N.d. N.d. N.d.

Tb 9,4 13,0 N.d.

Dy N.d. N.d. 7,0

Ho N.d. N.d. N.d.

Er N.d. N.d. 10,3

Tm N.d. N.d. N.d.

Yb 4,5 8,9 7,0

Lu 3,7 7,0 N.d.

K d (La)/K d (Yb) 1,96 2,25 0,47