Mineralogical and geochemical characteristics of the NNW-NNE trending Libiri doleritic dyke swarm of the Paleoproterozoic Liptako basement (West Niger): Genesis and magmatic evolution

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Table 2

Selected points are representative electron microprobe analysis results of feldspars.

Sample	TD2	TD1	TD1	TD2	SD	SD	SLB	SD

Minerals	Albite	Oligoclase	Andesine	Labradorite	Labradorite	Bytownite	Sanidine	Anorthoclase
SiO₂	64.300	60.250	56.040	53.940	51.820	49.030	72.130	70.960
TiO₂	0.000	0.010	0.000	0.090	0.020	0.000	0.050	0.030
Cr₂O₃	0.000	0.010	0.000	0.010	0.000	0.000	0.000	0.000
Al₂O₃	22.000	24.410	26.120	28.140	28.570	30.730	14.440	15.700
Fe₂O₃	0.000	0.000	0.000	0.142	1.300	0.733	0.000	0.000
FeO	0.660	0.410	0.750	0.742	0.000	0.000	0.070	0.110
MnO	0.020	0.040	0.000	0.000	0.000	0.070	0.000	0.000
NiO	0.010	0.000	0.010	0.020	0.030	0.050	0.000	0.010
MgO	0.210	0.010	0.040	0.110	0.170	0.340	0.000	0.010
CaO	1.660	6.380	9.360	11.630	13.030	15.340	0.130	0.150
Na₂O	8.850	7.400	5.700	4.740	3.980	2.840	1.220	2.780
K₂O	1.850	0.390	0.380	0.150	0.330	0.280	11.330	11.230
Total	99.560	99.310	98.400	99.714	99.250	99.413	99.370	100.98
Numbers of ions based on 8 oxygens
Si	2.860	2.711	2.569	2.453	2.380	2.255	3.396	3.206
Ti	0.000	0.000	0.000	0.003	0.001	0.000	0.002	0.001
Cr	0.000	0.000	0.000	0.000	0.000	0.000	0.000	0.000
Al	1.153	1.295	1.411	1.509	1.547	1.666	0.801	0.889
Fe3+	0.000	0.000	0.000	0.005	0.045	0.025	0.000	0.000
Fe2+	0.025	0.015	0.029	0.028	0.000	0.000	0.003	0.004
Mn	0.001	0.002	0.000	0.000	0.000	0.003	0.000	0.000
Ni	0.000	0.000	0.000	0.001	0.001	0.002	0.000	0.000
Mg	0.014	0.001	0.003	0.007	0.012	0.023	0.000	0.001
Ca	0.079	0.308	0.460	0.567	0.641	0.756	0.007	0.007
Na	0.763	0.646	0.506	0.418	0.354	0.253	0.111	0.244
K	0.105	0.022	0.022	0.009	0.019	0.016	0.680	0.647
Total	5.000	5.000	5.000	5.000	5.000	5.000	5.000	5.000
Ca [An]	0.084	0.315	0.465	0.570	0.632	0.737	0.008	0.008
Na [Ab]	0.806	0.662	0.512	0.421	0.349	0.247	0.139	0.271
K [Or]	0.111	0.023	0.022	0.009	0.019	0.016	0.852	0.721

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