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(a)
(b)
0.5134
0.702
MORB
MORB
Aleutian
Iceland
ls.
Guntur
0.5130
Samoa
Upolu
0.702
Guntur
Lesser Antilles
Hawaii
i
Ja
pan
B
ulk
Ea
rt
h
B
ul
k
E
a
rt
h
0.5126
0.702
EMII
Society Is.
Kerguelen
EMII
H K series
R
aratonga
HK series
Muriah
Banda Arc
Mariah
EMI
EMI
EK series
K series
HK calc +
Calc series
0.5122
0.702
Lesser Antilles
0.5118
0.702
0.702
0.704
0.706
0.708
0.7010
0.7012
0.702
0.704
0.706
0.702
0.702
0.702
87
86
87
86
Sr
/
Sr
Sr
/
Sr
Nd/
144
Nd versus
87
Sr/
86
Sr isotope diagram showing the Ringgit-Beser data relative
to Guntur and HK series lavas from Muriah (after Edwards et al. 1991)
143
Fig. 5.25
lavas. The Sr and Nd isotopic data however, differ from the K-rich lavas of Muriah,
which have lower
143
Nd/
144
Nd ratios at similar
87
Sr/
86
Sr ratios.
18
O%) with respect to
87
Sr/
86
Sr ratios for the
lavas of Ringgit-Beser is given in Fig.
5.26
. It may be noted that the K-rich lavas of
the area (+ 6.8
A plot of oxygen isotope data (
δ
±
0.2 %) lie within the mantle range for MORB, seamounts, and hot-
18
O versus
87
Sr/
86
Sr data suggest that only limited amounts of
crustal contamination is possible.
spot basalts. The
δ
16
Sediment
Indian Ocean
sediments
14
Crusted
contamination
+7.0
12
+6.5
R
inggit Beser
+6.0
10
Muriah K
series
0.704
0.705
Muriah HK
series
8
Galung gung
M
ORB
10 %
Calculated mixing curve
Between MORB & Indian
Ocean sediments
6
5 %
Mantle
1 %
Guntur
4
0.702
0.704
0.706
0.708
0.710
0.712
87
86
Sr /
Sr
Sr/
86
Sr diagram showing the whole rock data from Ringgit-Beser
relative to Guntur, MORB and mantle hot-spot basalts and seamounts (after Edwards et al. 1994).
The
206
Pb/
204
Pb ratios of the lavas from Ringgit-Beser Complex range from 18.493 to 18.915,
207
18
87
Fig. 5.26 The
δ
O versus
Pb/
204
Pb form 15.617 to 15.672 and
208
Pb/
204
Pb from 38.975 to 39.191. They also found that
the potassic lavas of Ringgit-Beser have less radiogenic Pb than calc-alkalic lavas. The EK series
lavas have higher
208
Pb/
204
Pb ratio than those of the K-series lavas of Ringgit-Beser Complex,
dominated by leucite-bearing rocks
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