“Rare Earth Plots” and the
Concentrations of Rare Earth Elements (REE)
in Chondritic Meteorites
The following sets of concentration values
have been used in the geochemical literature for the purpose
of
preparing
plots of “chondrite-normalized” concentrations of REE against
atomic number or inverse ionic radius. Note that the
oldest data, columns 1, 2, 3, 4, and 6, were obtained from
analysis of ordinary chondrites. Thus historically, “chondrite-normalized
REE plots” have been based
on volatile-free chondrites (Fig. 1). Columns 5, 7, 11,
and 13 represent CI (carbonaceous) chondrites, which contain
carbon, water, and other volatile elements, thus the values
are systematically
lower (Fig. 2). These values are based on more data and are
probably more precise and representative than the older OC
data.
In my experience, the values of Anders
and Grevesse (1989; column 11) consistently give the smoothest "REE
patterns" for the wide variety of rock types that we have
analyzed in our laboratory. However,
we only obtain data for 7 or 8 of the REE (e.g., Fig. A1 of Korotev,
1996). To maintain consistency with older literature,
I use the values of column 12, which are the CI values of Anders
and Grevesse (column 11) multiplied by the factor 1.36. This
factor leads to exactly 0.20 µg/g Sm and values for all REE
in the vicinity of those of columns 1, 2, 3, 4, and 6.
This approach follows the lead of Boynton (1985; column 8)
and Taylor
and McClennan (1985; column 9)
who chose slightly different normalization factors.
|
1) Haskin L. A., Wildeman T. R., and
Haskin M. A. (1968)
"An accurate procedure for the determination of the rare earths by neutron
activation"
Journal of Radioanalytical Chemistry 1,
337-348.
Haskin L. A., Helmke P. A., Paster T. P., and Allen R. O. (1971)
"Rare earths in meteoritic, terrestrial, and lunar matter"
In Activation Analysis in Geochemistry and Cosmochemistry, A. Brunfelt
and E. Steinnes, eds., Proc. NATO Conf. on Activation Analysis in Geochemistry,
pp. 201-218, Universitetsforlaget, Oslo.
Composite of nine (ordinary?) chondrites; error-weighted mean of 1968 and
1971 analyses |
2) Wakita H., Rey P., and Schmitt R.
A. (1971)
Elemental abundances of major, minor, and trace elements in Apollo 11 lunar
rocks, soil and core samples. Proceedings of the Apollo 11 Lunar Science
Conference, 1685-1717.
"composite of 12 chondrites," data in caption to Fig. 1 |
3) Masuda A., Nakamura N., and Tanaka
T. (1973)
"Fine structure of mutually normalized rare-earth patterns of chondrites"
Geochimica et Cosmochimica Acta 37, 239-248.
"Leedy" (Leedey)
chondrite (L6). Note that LL chondrites have high REE concentrations compared
to H and L chondrites [Fig. 1, W&K (1988)]. |
4) Nakamura N. (1974)
"Determination of REE, Ba, Fe, Mg, Na, and K in carbonaceous and ordinary
chondrites"
Geochimica et Cosmochimica Acta 38, 757-775.
Average of ten ordinary chondrites |
5) Evensen N.M., Hamilton P.J., and
O'Nions R.K. (1978)
"Rare-earth abundances in chondritic meteorites"
Geochimica et Cosmochimica Acta 42, 1199-1212.
"CI avg.", best estimate of unfractionated chondrites, many literature
analyses. The data averaged include data for normalized ordinary chondrites. |
6) Laul J.C. (1979)
"Neutron activation analysis of geologic materials"
Atomic Energy Review 17, 603-695. (Fig. 20 caption,
p. 683)
Same as values of Wakita et al. (1971), except for Ce |
7) Anders E. and Ebihara M. (1982)
"Solar-system abundances of the elements"
Geochimica et Cosmochimica Acta 46, 2363-2380. (Table
6)
Essentially, values of Evensen et al. (1978) divided by 1.0366, except
Tb (/1.055)
These values also favored by Wasson J.T. (1985) Meteorites: Their Record
of Early Solar-System History, 267 pp., Freeman, New York. (Table
D-1) and Wasson and Kallemeyn (1988) "Composition of chondrites," Philosophical
Transactions of the Royal Society A 325, 535-544. |
8) Boynton W. V. (1985)
Chapter 3. Cosmochemistry of the rare earth elements: Meteorite studies,
In Rare Earth Element Geochemistry (P. Henderson, ed.), (Developments
in Geochemistry 2), pp. 115-1522, Elsevier, Amsterdam.
Values of Evensen et al. multiplied by 1.267 to be consistent with the
average values of Haskin et al. (1968) and Wakita et al. (1972) |
9) Taylor S. R. and McClennan S. M. (1985)
The Continental Crust: Its Composition and Evolution
Blackwell, Oxford. 312 pp.
Values of Evensen et al. multiplied by 1.5 ["type 1 carbonaceous chondrite
(volatile-free: 1.5× original data)"]
These values are are distinctly higher than any of the other "volatile-free" values
(Fig. 2). |
10) Wasson J. T. and Kallemeyn G. W. (1988)
"Compositions of chondrites"
Philosophical Transactions of the Royal Society A 325,
535-544.
I never actually seen these values used; I include them here only
for reference. W&K (1988) list means for H, L, and LL chondrites
(Fig.
1). It's not clear from the paper what data were averaged.
I have averaged their means with a 45.8% H, 39.7% L, and 14.6%
LL weighting. These are the relative abundance ratios at this writing
for ~32,000 ordinary chondrites listed in the Meteoritical
Bulletin Database of the Meteoritical Society. Note
that the agreement is good with the original OC data
of columns 1 and 2. |
11) Anders E. and Grevesse N. (1989)
"Abundances of the elements: Meteoritic and solar"
Geochimica et Cosmochimica Acta 53, 197-214.
"Mean C1 Chondr." of Table 1 |
12) Values of Anders & Grevesse times 1.3596.
This factor gives Sm = 0.2000 µg/g and results in values for all REE in the
vicinity those for the early ordinary chondrite composites.
Some references in which this approach is taken are listed below:
Korotev R. L. (1996) A self-consistent compilation of elemental concentration
data for 93 geochemical reference samples. Geostandards Newsletter 20,
217–245.
Korotev R. L. (1996) On the relationship between the Apollo 16 ancient regolith
breccias and feldspathic fragmental breccias, and the composition of the
prebasin crust in the Central Highlands of the Moon. Meteoritics and
Planetary Science 31, 403–412. |
13) Palme. H. (1988)
"
Chemical abundances in meteorites"
Reviews in Modern Astronomy (G. Klare, editor), Springer,
Berlin pp. 28-51.
These are the author's data for the Orgueil CI chondrite. |
14) McDonough W. F. and Sun S.-
s.
(1995)
"
The composition of the Earth"
Chemical Geology 120, 223–253.
These data are averages for CI chondrites based on data of the previously
publshed means and new data. |
