Geoscience Reference
In-Depth Information
Table 2
Representative results of petrographic and petrologic whole-rock analyses
Sample ID
D1-001 D1-002 D1-003 D1-005 D1-006 D1-007 D2-002 D2-005 D2-007
Major oxides
SiO
2
44.70
43.90
44.67
44.01
44.41
45.07
44.23
44.54
45.30
TiO
2
0.12
0.09
0.09
0.09
0.08
0.10
0.12
0.10
0.09
Al
2
O
3
2.59
2.81
2.56
2.38
1.64
3.04
3.11
2.55
2.67
Fe
2
O
3
8.46
8.71
8.87
8.76
9.35
8.58
9.58
9.48
9.26
MnO
0.13
0.13
0.13
0.13
0.13
0.13
0.13
0.14
0.13
MgO
40.79
40.84
41.26
41.78
42.90
40.28
40.83
40.14
40.32
CaO
3.27
2.85
2.83
2.94
1.79
2.91
1.85
3.16
2.60
Na
2
O
0.08
0.12
0.06
0.07
0.04
0.12
0.00
0.02
0.13
K
2
O
0.01
0.01
0.02
0.01
0.01
0.02
0.02
0.02
0.03
P
2
O
5
0.00
0.00
0.00
0.00
0.01
0.00
0.01
0.01
0.01
Total
100.14
99.47
100.49
100.18
100.36
100.24
99.86
100.15 100.53
Trace elements (ppm)
Co
104
103
99
102
108
98
105
108
104
Cr
2,822
2,756
2,651
2,601
2,547
2,745
3,035
2,267
2,543
Ni
1,988
2,091
2,032
2,139
2,185
1,988
2,155
2,118
2,111
H
2
O
−
0.21
0.17
0.12
0.21
0.44
0.37
0.51
0.68
0.54
IGLS
1.62
2.29
2.21
1.58
2.7
2.12
7.07
5.05
5.84
Mg#
0.905
0.903
0.902
0.904
0.901
0.903
0.894
0.893
0.896
Mineral mode (point-counted)
Total count
1,452
1,277
1,202
1,246
1,624
2,003
1,490
2,284
2,021
Olivine
85.5
86.8
82.1
78.7
90.8
85.1
91.2
85.9
78.7
Orthopyroxene
8.0
8.1
12.4
14.1
4.2
7.8
6.5
9.8
14.0
Clinopyroxene
2.2
2.2
3.1
3.3
3.8
4.0
1.5
3.1
5.0
Plagioclase
3.5
1.6
1.0
2.6
0.6
2.2
0.1
0.9
1.6
Spinel
0.8
1.3
1.4
1.3
0.7
0.9
0.6
0.4
0.7
Degree of
serpentinization
24.0
34.4
47.5
31.9
42.7
43.8
74.2
61.1
61.3
Mineral mode (calculated)
Olivine
63.9
67.1
66.0
68.8
67.2
59.2
61.6
62.4
58.6
Orthopyroxene
20.6
16.8
20.6
16.8
25.1
26.6
28.1
22.6
29.6
Clinopyroxene
10.2
8.7
8.6
9.4
5.3
8.0
2.8
9.7
6.5
Plagioclase
5.0
6.2
4.3
4.3
1.4
5.7
6.1
4.6
4.8
Spinel
0.4
1.2
0.4
0.7
0.9
0.5
1.4
0.7
0.4
0.1
0.7
0.1
0.3
1.0
0.2
1.0
0.3
Residual sum
of squares
0.4
amounts (up to 7%) of plagioclase. Although all the peridotites are serpentinized,
peridotites from KH-98-1D1 are less serpentinized than those from KH-98-1D2.
Overall, proto-granular to porphyroclastic textures (Mercier and Nicolas
1975
)
are developed in the peridotites rather than cumulate textures (Fig.
2a, b
). Several
samples exhibit a mylonitic texture (Fig. 2c). Olivine and orthopyroxene crystals
are commonly coarse equidimensional or elongate large crystals with undulatory
extinction (Fig. 2a). In places, a porphyroclastic texture is developed, so that
fine-grained assemblages (olivine, clinopyroxene, orthopyroxene, amphibole, and
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