Table 14. Partial chemical composition and internal isochron mineral ages of monazites (m) and bastnaesites (b) of Bayan Obo.
[Ore type: d, disseminated ore; bd, banded ore. *, Age and isotope dilution analyses from Wang and others (1994); analysts: Wang Junwen and M. Tatsumoto. **, determinations by electron microprobe analysis (EPMA); analysts: J.M. Back and J.A. Minkin. RE oxides in weight percent; total U in parts per billion (ppb); Th and Pb concentrations in parts per million (ppm)]
|
Sample no. . . . . |
8B7 |
7B36-6 |
34-24 |
796-48,280 |
8B35-2 |
85-10,21-4 |
9B3-2 |
796-48,277 |
490,330 |
|
Mineral. . . . . . . |
b |
m |
m |
b |
m |
b |
m |
m |
m |
|
Ore type. . . . . . |
d |
d |
d |
bd |
bd |
d |
bd |
d |
bd |
|
Age (Ma)*. . . . . |
555+-11 |
553+-16 |
532+-3.1 |
496+-13 |
474+-4.5 |
475+-8 |
437+-9.4 |
432+-8.5 |
431+-2.7 |
|
La2O3** |
22.92 |
13.26 |
17.63 |
28.64 |
25.41 |
24.89 |
23.51 |
18.60 |
24.76 |
|
Nd2O3** |
10.53 |
11.27 |
10.80 |
7.83 |
8.37 |
10.90 |
8.22 |
10.03 |
7.45 |
|
Ce2O3** |
39.11 |
41.55 |
37.38 |
36.37 |
33.84 |
36.24 |
34.65 |
36.91 |
35.25 |
|
Pr2O3** |
3.87 |
4.06 |
3.84 |
2.96 |
2.72 |
3.48 |
2.94 |
3.40 |
2.80 |
|
U (ppb)* |
55.17 |
506.8 |
559.8 |
853.1 |
3,384 |
236.7 |
449.7 |
321.2 |
201.7 |
|
Th (ppm)* |
994.2 |
3,670 |
2,678 |
1,284 |
808.6 |
563.6 |
1,202 |
2,988 |
1,102 |
|
Pb (ppm)* |
27.23 |
142.7 |
115.2 |
29.60 |
29.06 |
15.61 |
68.37 |
60.98 |
32.42 |
|
Initial |
|
|
|
|
|
|
|
|
|
|
Sample no. . . . . |
7B31-23 |
7B31-2 |
7B31-9 |
7B30-20 |
796-48,278 |
796-48,270 |
9B9-3 |
12-6A |
|
|
Mineral. . . . . . . |
m |
m |
m |
m |
m |
m |
m |
m |
|
|
Ore type. . . . . . |
bd |
bd |
bd |
bd |
d |
bd |
bd |
d |
|
|
Age (Ma)*. . . . . |
429+-11 |
424+-5.6 |
418+-11 |
421+-3.3 |
419+-3.7 |
415+-17 |
404+-14 |
398+-9.7 |
|
|
La2O3** |
19.69 |
23.77 |
22.89 |
13.60 |
20.10 |
20.17 |
19.81 |
17.07 |
|
|
Nd2O3** |
10.98 |
9.13 |
9.54 |
13.61 |
10.31 |
9.63 |
10.88 |
12.85 |
|
|
Ce2O3** |
35.95 |
33.92 |
34.63 |
38.69 |
36.12 |
37.42 |
34.96 |
35.84 |
|
|
Pr2O3** |
3.58 |
3.20 |
2.90 |
4.32 |
3.45 |
3.32 |
3.18 |
3.98 |
|
|
U (ppb)* |
313.9 |
5,233 |
3,617 |
461.3 |
1,768 |
340.7 |
7,630 |
3,196 |
|
|
Th (ppm)* |
787.2 |
832.2 |
803.8 |
2,417 |
2,657 |
2,273 |
2,012 |
6,071 |
|
|
Pb (ppm)* |
28.34 |
139.2 |
34.95 |
55.54 |
51.86 |
43.44 |
50.82 |
194.8 |
|
|
Initial |
|
|
|
|
|
|
|
|
|
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Maintained by John Watson
Last updated 12.17.97