Table 2. Selected mineral analyses of high-grade schists and gneisses from Leg 161.

Table 2. Selected mineral analyses of high-grade schists and gneisses from Leg 161.


	High-grade schists										High-grade gneisses					Migmatites
Core	976E-14R-1	976E-14R-1	976E-14R-1	976E- 14R-1	976E-14R-1	976E- 14R-3	976E-14R-1	976E-14R-1	976E- 14R-1	976E- 14R-3	976B-97R-2	976B-97R-2	976B-97R-2	976B-97R-2	976B- 97R-2	976B-95R-2	976B-95R-2	976B-95R-2
Interval (cm)	40-45	40-45	40-45	40-45	40-45	10-14	40-45	40-45	40-45	10-14	111-114	111-114	111-114	111-114	111-114	22-25	22-25	22-25
Mineral	Grt	Grt	Grt	Bt	Bt	St	Pl	Pl	Pl	Pl	Grt	Grt	Bt	Pl	Crd	Bt	Crd	Crd
	Outer rim	Rim	Core	Incl. in Grt	Matrix	Incl. in Grt	Rim	Core	Incl. in Grt	Incl. in Grt	Int. Rim	Core	Matrix	Matrix	Close to Grt	Matrix	Core	Rim
SiO₂	37.63	37.27	36.36	33.48	34.55	26.1	55.81	51.57	57.62	51.25	38.01	37.99	35.01	57.34	46.94	35.05	47.51	47.97
TiO₂	—	—	0.1	3.27	3.08	0.53	—	—	—	—	0.15	—	1.17	—	0.14	2.67	—	—
Al₂O₃	21.93	22.1	20.89	20.07	21.03	58.34	28.36	32.05	26.53	32.12	21.48	22.05	20.97	27.77	37	20.46	34.07	33.3
FeO	36.63	36.26	29.27	24.04	23.64	13.43	0.27	—	0.39	0.33	34.48	35.61	23.4	—	8.09	23.23	5.99	7.24
MnO	1.73	1.38	5.71	—	—	—	—	—	—	—	2.32	1.43	—	—	—	0.14	0.37	0.21
MgO	1.97	1.89	0.85	5.53	4.68	0.66	—	—	—	—	2.02	1.91	6.02	—	2.93	6.89	9.87	8.98
CaO	1.6	1.65	4.53	—	—	—	9.25	12.81	7.65	12.96	1.19	1.48	—	8.25	0.53	—	—	—
Na₂O	—	0.36	—	0.19	—	0.32	6.71	4.18	7.83	4.19	0.59	—	0.35	7.18	—	-0.77	0.78
K₂O	—	—	—	9.21	9.22	—	—	—	0.25	—	—	—	9.05	—	1.12	9.38	—	—
Total	101.49	100.91	97.71	95.79	96.2	99.39	100.41	100.61	100.27	100.84	100.25	100.47	95.96	100.54	96.75	97.82	98.58	98.48
Oxygens	12	12	12	22	22	46	8	8	8	8	12	12	22	8	18	22	18	18
Si	2.995	2.979	3.004	5.196	5.295	7.118	2.503	2.323	2.584	2.31	3.043	3.031	5.367	2.554	4.914	5.278	4.858	4.929
Al	2.057	2.082	2.034	3.671	3.799	18.753	1.499	1.702	1.402	1.706	2.027	2.074	3.789	1.458	4.566	3.631	4.106	4.033
Fe³⁺	—	0.016	—	0.09	0.192	—	—	—	—	—	—	—	—	—	—	0.016	—	—
Fe²⁺	2.438	2.407	2.022	3.022	2.838	3.063	0.01	—	0.015	0.012	2.309	2.376	3.001	—	0.708	2.91	0.512	0.622
Mg	0.234	0.225	0.105	1.279	1.069	0.268	—	—	—	—	0.241	0.227	1.375	—	0.457	1.547	1.505	1.376
Ca	0.136	0.141	0.401	—	—	—	0.444	0.618	0.368	0.626	0.102	0.127	—	0.394	0.059	—	—	—
Na	—	0.056	—	0.057	—	0.169	0.583	0.365	0.681	0.366	0.091	—	0.103	0.621	—	—	0.153	0.155
K	—	—	—	1.823	1.803	—	—	—	0.014	—	—	—	1.77	—	0.15	1.802	—	—
Ti	—	—	0.006	0.382	0.355	0.109	—	—	—	—	0.009	—	0.135	-0.011	0.302	—	—
Mn	0.117	0.093	0.4	—	—	—	—	—	—	—	0.157	0.097	—	—	—	0.018	0.032	0.018
Total Cat.	7.977	8	7.972	15.528	15.352	29.481	5.04	5.008	5.063	5.02	7.98	7.932	15.54	5.027	10.866	15.505	11.165	11.133
Fe/(Fe+Mg)	0.91	0.91	0.95	0.70	0.73	0.92	—	—	—	—	0.91	0.91	0.69	—	0.61	0.65	0.25	0.31
Alm%	83.35	83.985	69.057	—	—	—	—	—	—	—	82.2	84.047	—	—	—	—	—	—
Prp%	8	7.8507	3.5861	—	—	—	—	—	—	—	8.5796	8.0297	—	—	—	—	—	—
Grs%	4.6496	4.9197	13.695	—	—	—	—	—	—	—	3.6312	4.4924	—	—	—	—	—	—
Sps%	4	3.2449	13.661	—	—	—	—	—	—	—	5.5892	3.4312	—	—	—	—	—	—
Ab%	—	—	—	—	—	—	56.761	37.126	64.065	36.911	—		—	61.183	—	—	—	—
An%	—	—	—	—	—	—	43.239	62.874	34.589	63.089	—		—	38.817	—	—	—	—

Notes: Samples from Cores 161-976E-14R-1 and 976E-14R-3 are high-grade schists, while sample from Core 976E-95R-2 is a high-grade gneiss. Analyses were obtained by a Cambridge S360 SEM equipped with a LINK AN 1000ED detector (CNR Chimica dei Plasmi, instrument hosted in Dip. Geomineralogico, University of Bari). Operation conditions were: 15 kV accelerating potential, 1 nA probe current. For standardization several minerals and pure compounds manufactured by Micro-Analysis Consultants Ltd were used. Fe³⁺ in biotite has been calculated using the Dymek (1983) approach.