Eclogitic metagabbro from the Lanzada Window, eastern Central Alps: confirmation of subduction beneath the Malenco Unit

Droop, Giles T. R.; Chavrit, Déborah

doi:10.1007/s00015-014-0162-z

Swiss Journal of Geosciences

Table 1 Representative electron-microprobe analyses of peak-metamorphic and retrograde minerals

From: Eclogitic metagabbro from the Lanzada Window, eastern Central Alps: confirmation of subduction beneath the Malenco Unit

	Garnet 1 Core	Garnet 2 Intermed.	Garnet 3 Near rim	Garnet 4 Rim cont. Cpx	Omphacite 1 Core Cpx agg.	Omphacite 2 Core near Grt	Omphacite 3 Core cont. Ep	Omphacite 4 Rim cont. Grt	Epidote 1 Core dist. Cpx	Epidote 2 Rim dist. Cpx	Epidote 3 Rim cont. Grt	Phengite 1 Core	Phengite 2 Core	Titanite 1 Small cont. Cpx	Hornblende 1 Core	Hornblende 2 Rim cont. Cpx	Albite 1 Poik
Oxides
SiO₂	37.20	37.50	37.66	37.63	54.71	55.65	55.06	55.55	38.66	38.29	36.94	49.50	49.49	30.34	49.18	48.93	67.87
TiO₂	0.16	0.11	0.08	0.07	0.24	0.06	0.07	0.04	0.13	0.13	0.11	0.35	0.41	38.60	0.20	0.20	0.00
Al₂O₃	21.14	21.05	21.35	21.63	6.86	10.95	10.31	10.80	29.35	27.00	22.19	29.19	28.93	1.30	7.72	8.13	20.11
Cr₂O₃	0.03	0.02	0.02	0.01	0.00	0.02	0.04	0.02	0.03	0.02	0.03	0.01	0.00	0.02	0.01	0.03	0.00
Fe₂O₃	–	–	–	–	2.26	3.59	4.60	4.82	5.87	8.59	15.08	0.00	0.00	–	4.25	4.55	0.10
FeO	27.77	27.64	26.18	25.18	4.23	4.18	3.92	3.16	–	–	–	3.12	3.18	0.32	8.80	9.03	–
MnO	2.01	1.89	1.06	1.51	0.25	0.31	0.32	0.25	0.05	0.20	0.37	0.05	0.02	0.07	0.45	0.46	0.00
MgO	1.16	1.27	1.70	1.69	10.10	6.34	6.25	6.46	0.05	0.04	0.00	3.26	3.23	0.01	13.44	13.11	0.00
CaO	10.53	10.82	12.18	12.84	17.01	11.31	11.42	10.98	23.88	23.62	23.09	0.04	0.03	28.37	9.52	9.66	0.29
Na₂O	0.00	0.00	0.00	0.00	4.61	7.83	7.74	8.08	0.00	0.00	0.00	0.51	0.57	0.01	2.96	2.79	11.46
K₂O	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.01	9.97	9.89	0.00	0.36	0.43	0.04
Total	100.00	100.30	100.23	100.57	100.26	100.24	99.73	100.17	98.02	97.89	97.82	95.97	95.74	99.04	96.88	97.30	99.86
Formula	12(O)	12(O)	12(O)	12(O)	6(O)	6(O)	6(O)	6(O)	12.5(O)	12.5(O)	12.5(O)	11(O)	11(O)	5(O)	23(O)	23(O)	8(O)
Si	2.976	2.988	2.982	2.966	1.978	1.991	1.987	1.986	2.987	2.996	2.971	3.289	3.297	0.999	7.151	7.100	2.969
Ti	0.009	0.006	0.005	0.004	0.006	0.002	0.002	0.001	0.008	0.008	0.007	0.017	0.020	0.956	0.022	0.022	0.000
Al	1.994	1.977	1.992	2.009	0.292	0.462	0.439	0.455	2.673	2.490	2.104	2.286	2.271	0.050	1.323	1.391	1.037
Cr	0.002	0.001	0.001	0.001	0.000	0.001	0.001	0.001	0.002	0.001	0.002	0.001	0.000	0.000	0.001	0.003	0.000
Fe³⁺	–	–	–	–	0.061	0.097	0.125	0.130	0.341	0.506	0.913	0.000	0.000	-	0.465	0.497	0.003
Fe²⁺	1.858	1.842	1.733	1.660	0.128	0.125	0.118	0.095	-	-	-	0.173	0.177	0.009	1.070	1.096	-
Mn	0.136	0.128	0.071	0.101	0.008	0.009	0.010	0.008	0.003	0.013	0.025	0.003	0.001	0.002	0.055	0.056	0.000
Mg	0.139	0.151	0.201	0.199	0.544	0.338	0.336	0.344	0.006	0.005	0.000	0.322	0.321	0.000	2.913	2.835	0.000
Ca	0.902	0.924	1.033	1.084	0.659	0.433	0.441	0.421	1.977	1.980	1.990	0.003	0.002	1.001	1.482	1.501	0.014
Na	0.00	0.00	0.00	0.00	0.323	0.543	0.541	0.560	0.000	0.000	0.000	0.065	0.073	0.001	0.833	0.784	0.972
K	0.00	0.00	0.00	0.00	0.000	0.000	0.000	0.000	0.000	0.000	0.001	0.845	0.841	0.000	0.067	0.080	0.002
Total	8.017	8.017	8.017	8.025	4.000	4.000	4.000	4.000	7.997	7.999	8.013	7.005	7.004	3.019	15.382	15.365	4.998
Mg/(Mg+Fe²⁺)	0.069	0.076	0.104	0.107	0.810	0.730	0.740	0.784	–	–	–	0.650	0.644	–	0.731	0.721	–

Garnet analyses 1, 2 and 4 are from the same porphyroblast; epidote analyses 1 and 2 are from the same crystal; all other analyses are from different crystals
cont contacting, dist distant from, Cpx agg in interior of Cpx aggregate, poik poikiloblast

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