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Table T5. Igneous unit and contact log, Hole 1256D.

Upper contact
Nature of contact/
Rationale for boundary
Minimum thickness (m)

Unit/Subunit
Core, section, piece, interval
Depth (mbsf)
Rock type










309-1256D-



27
75R-1 (Piece 1, 0 cm)
752.0
Chilled margin
3.17
Aphyric cryptocrystalline to microcrystalline basaltic sheet flow
28
77R-1 (Piece 16, 66 cm)
759.4
Chilled margin
3.69
Sparsely to moderately phyric cryptocrystalline to fine-grained basaltic sheet flow
29a
78R-3 (Piece 2, 10 cm)
766.5
Breccia and chilled margin
3.53
Aphyric cryptocrystalline to microcrystalline basaltic sheet flow
29b
80R-1 (Piece 2, 3 cm)
779.2
Breccia and chilled margin
8.59
Aphyric cryptocrystalline to fine-grained basaltic sheet flow
30
84R-2 (Piece 10, 60 cm)
803.9
Textural change
3.16
Massive aphyric fine-grained basalt
31
85R-3 (Piece 3, 24 cm)
814.6
Chilled margin
11.27
Massive aphyric fine-grained basalt
32
88R-1 (Piece 9, 49 cm)
840.7
Textural change
0.93
Aphyric fine-grained sheet flow
33a
89R-1 (Piece 1, 0 cm)
849.8
Different style of eruption
9.19
Aphyric microcrystalline sheet flow
33b
99R-1(Piece 1, 0 cm)
907.4
Textural change (more massive and coarse grained)
2.45
Aphyric fine-grained basaltic sheet flow
34a
100R-1 (Piece 2, 6 cm)
910.7
Breccia (containing clasts with chilled margin)
2.72
Massive aphyric microcrystalline to fine-grained basalt
34b
101R-2 (Piece 7, 33 cm)
918.8
Rubble, change in fracturation and alteration features
2.49
Massive aphyric fine-grained basalt
35a
102R-3 (Piece 6, 24 cm)
929.8
Textural change
2.71
Aphyric cryptocrystalline to fine grained basaltic sheet flow
35b
106R-1 (Piece 16, 67 cm)
951.1
Phenocrysts (sparsely olivine-clinopyroxene-plagioclase phyric)
0.32
Sparsely phyric cryptocrystalline to microcrystalline sheet flow
35c
106R-1 (Piece 24, 108 cm)
951.5
Return to aphyric texture
2.14
Aphyric cryptocrystalline to microcrystalline basaltic sheet flow
36a
108R-2 (Piece 11, 61 cm)
960.9
Breccia, textural change
3.56
Massive aphyric microcrystalline basalt
36b
110R-1 (Piece 3, 26 cm)
969.9
Textural change
2.85
Massive aphyric microcrystalline basalt
36c
111R-1 (Piece 2, 25 cm)
974.7
Textural change
1.39
Massive aphyric microcrystalline basalt
37
112R-1 (Piece 10, 75 cm)
980.0
Textural change, phenocrysts (sparsely cpx-plag phyric)
0.89
Sparsely phyric cryptocrystalline to microcrystalline sheet flow
38
113R-1 (Piece 10, 38 cm)
984.4
Breccia (containing clasts with chilled margin)
2.15
Aphyric microcrystalline to fine-grained sheet flow
39a
114R-1 (Piece 12, 112 cm)
989.9
Moderate vesicular, breccia with cryptocrystalline clasts
0.81
Massive sparsely phyric moderately vesicular microcrystalline basalt
39b
114R-2 (Piece 10, 66 cm)
990.9
Textural change (disappearance of vesicles)
3.38
Massive aphyric microcrystalline basalt
40
117R-1 (Piece 6, 85 cm)
1004.1
Textural change, brecciation
1.67
Cataclastic-massive basaltic unit
41
118R-1 (Piece 8, 66 cm)
1008.7
Textural change
3.87
Aphyric microcrystalline basaltic sheet flow
42a
122R-1 (Piece 7, 25 cm)
1027.6
Textural change (volcanic breccia)
1.30
Mineralized volcanic breccia
42b
122R-2 (Piece 4, 30 cm)
1029.1
Volcanic breccia is interbedded with sheet flow
1.47
Mineralized volcanic breccia intercalated with aphyric cryptocrystalline basaltic sheet flow
43
123R-1 (Piece 24, 109 cm)
1033.2
Textural change
4.40
Aphyric microcrystalline basaltic sheet flow
44a
129R-1 (Piece 1, 0 cm)
1060.9
Textural change
1.96
Massive aphyric microcrystalline basalt
44b
130R-1 (Piece 1, 0 cm)
1065.7
Breccia, textural change
2.34
Massive aphyric microcrystalline basalt
44c
131R-1 (Piece 1, 0 cm)
1070.5
Textural change
4.41
Massive aphyric microcrystalline basalt
44d
133R-1 (Piece 5, 108 cm)
1081.2
Textural change
3.54
Massive aphyric microcrystalline basalt
45
135R-1 (Piece 10, 101 cm)
1090.7
Breccia
2.83
Massive aphyric microcrystalline basalt
46a
137R-1 (Piece 16, 105 cm)
1100.4
Textural change
2.24
Massive aphyric microcrystalline basalt
46b
139R-1 (Piece 2, 8 cm)
1109.0
Textural change and possible contact
1.63
Massive aphyric microcrystalline basalt
47
140R-1 (Piece 4, 19 cm)
1113.9
Complex brecciated intrusive contact
0.90
Intrusive contact breccia and aphyric fine-grained basalt
48
141R-1 (Piece 2, 9 cm)
1118.6
Brecciated chilled margin
3.59
Massive aphyric microcrystalline to fine-grained basalt
49
143R-1 (Piece 12, 56 cm)
1128.7
Breccia, dike contact
0.94
Aphyric microcrystalline basalt
50
143R-2 (Piece 6, 22 cm)
1129.8
Change of phenocryst content (olivine + clinopyroxene)
9.61
Massive sparsely phyric microcrystalline basalt
51
147R-1 (Piece 5, 19 cm)
1145.4
Textural change (more coarse grained)
0.97
Doleritic basalt
52a
148R-1 (Piece 1, 0 cm)
1151.1
Textural change
3.77
Massive aphyric microcrystalline basalt
52b
149R-1

Intrusive contact

Aphyric cryptocrystalline basalt
52c
151R-1

Intrusive contact

Aphyric cryptocrystalline basalt
53a
152R-1 (Piece 1, 0 cm)
1169.9
Textural change
3.00
Massive aphyric fine-grained basalt
53b
153R-2

Intrusive contact

Aphyric cryptocrystalline basalt
54
154R-1 (Piece 1, 0 cm)
1179.6
Textural change
4.68
Massive aphyric microcrystalline basalt
55a
156R-1 (Piece 1, 0 cm)
1189.4
Textural change
6.06
Massive aphyric microcrystalline basalt
55b
157R-1

Intrusive contact

Aphyric microcrystalline basalt
56a
159R-1 (Piece 16, 93 cm)
1204.7
Textural change
3.94
Massive aphyric cryptocrystalline to microcrystalline basalt
56b
161R-1

Intrusive contact

Aphyric cryptocrystalline basalt
57a
162R-1 (Piece 9, 65 cm)
1214.1
Textural change
4.93
Massive aphyric cryptocrystalline-microcrystalline basalt
57b
162R-3
1216.4
Intrusive contact

Aphyric cryptocrystalline basalt
57c
163R-2
1219.5
Textural change and intrusive contact

Aphyric cryptocrystalline basalt
58
163R-3 (Piece 1, 0 cm)
1221.0
Textural change
2.83
Massive aphyric cryptocrystalline to microcrystalline basalt
59
164R-2 (Piece 9, 45 cm)
1225.0
Textural change
0.98
Massive aphyric microcrystalline basalt
60a
164R-3 (Piece 3, 16 cm)
1226.2
Textural change
3.69
Massive aphyric microcrystalline basalt
60b
165R-3

Intrusive contact

Aphyric cryptocrystalline dike
61a
166R-1 (Piece 1, 0 cm)
1232.6
Textural change
3.56
Massive aphyric microcrystalline basalt
61b
166R-1

Intrusive contact

Aphyric cryptocrystalline dike
62
167R-1 (Piece 1, 0 cm)
1236.4
Textural change
3.01
Massive aphyric-sparsely phyric microcrystalline basalt
63
167R-3 (Piece 11, 73 cm)
1239.8
Breccia, textural change
6.37
Massive aphyric microcrystalline basalt
64
169R-1 (Piece 9, 60 cm)
1247.6
Textural change
4.32
Massive aphyric microcrystalline basalt
65
170R-2 (Piece 12, 104 cm)
1254.2
Textural change
1.15
Massive aphyric microcrystalline basalt









Note: cpx = clinopyroxene, plag = plagioclase.

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