The Signature of Amphibole in Mafic Alkaline Lavas, a Study in the ...

Nb
88-
94-
88
82-
85-
52-
42-
41-
34-
33-
31-
29-
30-
28-
26-
Ta
4-4
Cr
350-
Co
57-
Ni
229-
Th
7-7
U
2-1
Rare earth elements (p.p.m.)
La
80-5
Ce
1400
Nd
620
Sm
14-23
Eu
409
Tb
1-40
Ho
—
4-6
331-
53-
240-
83
2-2
76-1
139 0
640
1400
3-91
1-30
1-30
4 1
341-
56-
243-
7 1
1-8
73-5
1320
580
11-93
3-70
1-20
—
40
364-
56-
281-
70
1-9
70-3
1250
540
12-31
3-56
1-11
—
4-2
363-
59-
284-
70
20
68-9
1210
540
12-23
3-63
1-20
—
25
382-
60-
297-
4-2
10
38-2
740
360
7-79
2-45
0-85
—
2-2
313-
58-
238-
32
10
30-1
56-7
280
6-99
205
0-78
0-70
1-8
287
54-
196-
30
0-9
25-8
540
270
6-26
200
0-80
0-80
1-7
349-
60-
238-
2-6
0-8
21-9
44-6
21 0
5-39
1-83
063
0 70
1-6
331
56-
222-
2-3
0-8
21-1
42-4
220
5-64
1-71
—
0-90
1-6
317-
55-
215
21
0-8
19-4
39-9
190
5-43
1-64
0-65
0-70
Downloaded from petrology.oxfordjournals.org at McGill University Libraries on September 29, 2011
317
1-4
58-
221-
2-2
0-7
20-2
39-3
200
4-93
1-68
0-56
0-60
1-5
308-
56-
217
2-1
0-6
200
370
190
5-16
1-63
0-64
0 70
1-4
3000
55-
217-
20
0-6
18-8
37-1
190
506
1-59
0-63
—
1-7
277-
54-
235-
2-4
0-8
20-3
380
200
4-99
1-56
0-68
0-70
Yb
1-40
1-50
1-40
1 -40
1-30
1-30
1-20
1-50
1-20
1-30
1-30
1-30
1-30
1-30
1-40
Lu
0-15
0-18
0-17
0-17
0-16
0-14
0 18
0-16
0-16
0-15
0-20
0-20
0-21
0-19
020
Foid
34-78
34-40
33-16
32-36
32-43
15-54
10-67
808
6-11
523
507
4-44
4-29
2-68
—
Opx
—
—
—
—
—
—
—
—
—
—
—
—
-
—
2-72
LOI, loss on ignition.
The major elements and the trace elements Ba, Rb, Sr, Nb, Zr, Y, V, Cr and Ni were analysed by X-ray fluorescence (XFR) spectrometry at McGill University with a Philips PW 1400
spectrometer. The major elements and Ba, V, Co, Cr and Ni were analysed on fused discs using an a-coefficient technique. Where given, Fe 3+ was calculated as Fe tot - Fe 2 *, where Fe 2 +
was determined by titration, otherwise total Fe is given as FeO. The analytical precision (1 SD in wt %) calculated from 20 replicate analyses on one disc is: Si 005, Al 003, Cr 0001, Mg
0058, Fe 001, Mn 0001, Ni 0004, Ca 001, Na 006, K 0001 and P 0004. The other XRF trace elements were analysed on pressed powder pellets using a Rh Kb Compton scatter
matrix correction. The relative analytical precision of these elements is estimated to be 5%. The REE, Sc, Hf, Ta, U and Th were analysed by instrumental neutron activation at the University
de Montreal. The samples were irradiated in a flux of 10 neutrons/cm/s for 4 h in a SLOWPOKE II reactor and counted over a period of 6 weeks on two Ge detectors with resolutions
of 0-6 and 1 -2 keV. The relative analytical precisions for La, Sm, Eu, Yb and Sc are estimated to be 5%, and those for Ce, Nd, Ho, Tb, Lu and Ta are ~10%. The normative
amounts of feldspathoid or orthopyroxene are calculated in oxygen units assuming Fe 3+ /Fe to ' = 0-10. See Francis & Ludden (1990) for Fort Selkirk analyses.