Table T5. Microprobe analyses of orthopyroxene in Leg 176 gabbros.

Table T5. Microprobe analyses of orthopyroxene in Leg 176 gabbros.

Sample:*

MS9-4

MS14-7

MS22-11

MS41-18

MS70-20

MS97-35

GS44-8

GS77-11

GS86-13

GS86-13

GS100-17

GS51-18

N:

1

1

9

7

8

5

3

5

2

5

3

3

C

C

F

C

F

C

Major element oxides (wt%):

SiO₂ 52.45 55.51 53.72 52.50 53.39 54.44 52.53 55.15 54.87 54.47 55.61 50.93

TiO₂ 0.12 0.33 0.44 0.38 0.40 0.33 0.24 0.36 0.31 0.48 0.31 0.44

Al₂O₃ 2.57 2.35 1.15 0.84 1.19 1.43 1.07 1.28 1.19 1.15 1.30 1.03

FeOt 10.59 15.27 18.96 23.68 18.71 14.33 16.71 16.35 17.44 18.01 13.81 20.59

MnO 0.23 0.33 0.49 0.64 0.46 0.33 0.40 0.36 0.37 0.41 0.31 0.57

MgO 28.11 25.50 24.55 20.89 24.11 27.54 25.93 25.79 25.52 24.78 27.88 22.45

CaO 3.73 2.98 1.61 1.42 2.07 1.01 1.13 1.46 0.95 1.31 1.01 1.84

Na₂O 0.10 0.30 0.03 0.02 0.03 0.02 0.01 0.03 0.02 0.02 0.01 0.04

K₂O 0.00 0.02 0.01 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.01 0.00

P₂O₅ 0.00 0.03 0.01 0.01 0.01 0.01 0.01 0.01 0.02 0.01 0.01 0.01

NiO 0.06 0.00 0.02 0.01 0.02 0.02 0.03 0.03 0.00 0.02 0.04 0.01

Cr₂O₃ 0.60 0.05 0.01 0.00 0.01 0.01 0.02 0.02 0.03 0.03 0.03 0.01

Total: 98.55 102.66 100.99 100.40 100.42 99.49 98.09 100.84 100.72 100.69 100.33 97.91

Calculated cation proportions:

Si 1.9035 1.9565 1.9569 1.9683 1.9570 1.9641 1.9517 1.9805 1.9801 1.9754 1.9808 1.9404

Ti 0.0033 0.0087 0.0119 0.0107 0.0110 0.0091 0.0068 0.0097 0.0085 0.0131 0.0084 0.0126

Al 0.1100 0.0975 0.0493 0.0372 0.0516 0.0608 0.0470 0.0541 0.0508 0.0493 0.0548 0.0460

Cr 0.0171 0.0013 0.0003 0.0001 0.0004 0.0004 0.0006 0.0004 0.0008 0.0009 0.0008 0.0002

Fe 0.3208 0.4492 0.5767 0.7413 0.5727 0.4315 0.5183 0.4902 0.5253 0.5452 0.4108 0.6551

Mn 0.0070 0.0098 0.0151 0.0203 0.0143 0.0101 0.0124 0.0111 0.0112 0.0124 0.0093 0.0183

Mg 1.5196 1.3389 1.3323 1.1665 1.3165 1.4799 1.4352 1.3794 1.3716 1.3385 1.4791 1.2743

Ca 0.1448 0.1125 0.0628 0.0572 0.0812 0.0392 0.0450 0.0562 0.0368 0.0510 0.0385 0.0750

Na 0.0068 0.0207 0.0018 0.0012 0.0022 0.0017 0.0010 0.0018 0.0013 0.0012 0.0009 0.0033

K 0.0000 0.0008 0.0003 0.0001 0.0002 0.0004 0.0001 0.0002 0.0001 0.0001 0.0003 0.0000

Total: 4.0330 3.9961 4.0074 4.0030 4.0072 3.9972 4.0182 3.9835 3.9864 3.9871 3.9836 4.0254

Mg# 85.6 74.5 70.3 61.3 70.2 77.2 74.9 72.5 71.3 70.1 76.9 67.8

1 NA NA 0.81 0.40 0.58 1.1 0.72 0.36 0.08 1.0 0.38 1.2

Wo 10.4 9.4 5.5 5.5 7.0 3.1 3.8 4.7 3.2 4.4 3.0 6.9

En 76.7 67.5 66.5 58.0 65.3 74.8 72.0 69.1 69.0 67.0 74.6 63.2

Fs 12.9 23.1 28.0 36.5 27.7 22.1 24.2 26.2 27.8 28.6 22.4 29.9

Sample:*	MS9-4	MS14-7	MS22-11	MS41-18	MS70-20	MS97-35	GS44-8	GS77-11	GS86-13	GS86-13	GS100-17	GS51-18
N:	1	1	9	7	8	5	3	5	2	5	3	3
							C	C	F	C	F	C
Major element oxides (wt%):
SiO₂	52.45	55.51	53.72	52.50	53.39	54.44	52.53	55.15	54.87	54.47	55.61	50.93
TiO₂	0.12	0.33	0.44	0.38	0.40	0.33	0.24	0.36	0.31	0.48	0.31	0.44
Al₂O₃	2.57	2.35	1.15	0.84	1.19	1.43	1.07	1.28	1.19	1.15	1.30	1.03
FeOt	10.59	15.27	18.96	23.68	18.71	14.33	16.71	16.35	17.44	18.01	13.81	20.59
MnO	0.23	0.33	0.49	0.64	0.46	0.33	0.40	0.36	0.37	0.41	0.31	0.57
MgO	28.11	25.50	24.55	20.89	24.11	27.54	25.93	25.79	25.52	24.78	27.88	22.45
CaO	3.73	2.98	1.61	1.42	2.07	1.01	1.13	1.46	0.95	1.31	1.01	1.84
Na₂O	0.10	0.30	0.03	0.02	0.03	0.02	0.01	0.03	0.02	0.02	0.01	0.04
K₂O	0.00	0.02	0.01	0.00	0.00	0.01	0.00	0.00	0.00	0.00	0.01	0.00
P₂O₅	0.00	0.03	0.01	0.01	0.01	0.01	0.01	0.01	0.02	0.01	0.01	0.01
NiO	0.06	0.00	0.02	0.01	0.02	0.02	0.03	0.03	0.00	0.02	0.04	0.01
Cr₂O₃	0.60	0.05	0.01	0.00	0.01	0.01	0.02	0.02	0.03	0.03	0.03	0.01
Total:	98.55	102.66	100.99	100.40	100.42	99.49	98.09	100.84	100.72	100.69	100.33	97.91
Calculated cation proportions:
Si	1.9035	1.9565	1.9569	1.9683	1.9570	1.9641	1.9517	1.9805	1.9801	1.9754	1.9808	1.9404
Ti	0.0033	0.0087	0.0119	0.0107	0.0110	0.0091	0.0068	0.0097	0.0085	0.0131	0.0084	0.0126
Al	0.1100	0.0975	0.0493	0.0372	0.0516	0.0608	0.0470	0.0541	0.0508	0.0493	0.0548	0.0460
Cr	0.0171	0.0013	0.0003	0.0001	0.0004	0.0004	0.0006	0.0004	0.0008	0.0009	0.0008	0.0002
Fe	0.3208	0.4492	0.5767	0.7413	0.5727	0.4315	0.5183	0.4902	0.5253	0.5452	0.4108	0.6551
Mn	0.0070	0.0098	0.0151	0.0203	0.0143	0.0101	0.0124	0.0111	0.0112	0.0124	0.0093	0.0183
Mg	1.5196	1.3389	1.3323	1.1665	1.3165	1.4799	1.4352	1.3794	1.3716	1.3385	1.4791	1.2743
Ca	0.1448	0.1125	0.0628	0.0572	0.0812	0.0392	0.0450	0.0562	0.0368	0.0510	0.0385	0.0750
Na	0.0068	0.0207	0.0018	0.0012	0.0022	0.0017	0.0010	0.0018	0.0013	0.0012	0.0009	0.0033
K	0.0000	0.0008	0.0003	0.0001	0.0002	0.0004	0.0001	0.0002	0.0001	0.0001	0.0003	0.0000
Total:	4.0330	3.9961	4.0074	4.0030	4.0072	3.9972	4.0182	3.9835	3.9864	3.9871	3.9836	4.0254
Mg#	85.6	74.5	70.3	61.3	70.2	77.2	74.9	72.5	71.3	70.1	76.9	67.8
1	NA	NA	0.81	0.40	0.58	1.1	0.72	0.36	0.08	1.0	0.38	1.2
Wo	10.4	9.4	5.5	5.5	7.0	3.1	3.8	4.7	3.2	4.4	3.0	6.9
En	76.7	67.5	66.5	58.0	65.3	74.8	72.0	69.1	69.0	67.0	74.6	63.2
Fs	12.9	23.1	28.0	36.5	27.7	22.1	24.2	26.2	27.8	28.6	22.4	29.9

Notes: * = ODP sample designations are found in Table T1. N = averages of a number of point analyses on more than one crystal in a thin section are reported. NA = not analyzed. The analyses were done on a JXA-8800L Superprobe at The University of Queensland. See text for analytical details. F (fine) and C (coarse) in GS samples refer to fine-grained microgabbro "bands" or "veins" entrued or enclosed within coarse-grained gabbro host. Note that nonsystematic compositional differences exist between averaged F and C portions of the same samples, but these differences are within the expected within sample variations. Wo = wollastonite, En = enstatite, Fs = ferrosilite.