Table T13. Igneous unit and contact log, Hole 1256D, Expedition 309.
| Unit | Upper contact | Nature of contact/ Rationale for boundary |
Minimum thickness (m) |
Rock type | |
|---|---|---|---|---|---|
| Core, section, piece, interval (cm) |
Depth (mbsf) |
||||
| 309-1256D- | |||||
| 1256D-27 | 75R-1 (Piece 1, 0) | 752.0 | Chilled margin | 3.17 | Aphyric cryptocrystalline to microcrystalline basaltic sheet flow |
| 1256D-28 | 77R-1 (Piece 16, 66) | 759.4 | Chilled margin | 3.69 | Sparsely to moderately phyric cryptocrystalline to fine-grained basaltic sheet flow |
| 1256D-29a | 78R-3 (Piece 2, 10) | 766.5 | Breccia and chilled margin | 3.53 | Aphyric cryptocrystalline to microcrystalline basaltic sheet flow |
| 1256D-29b | 80R-1 (Piece 2, 3) | 779.2 | Breccia and chilled margin | 8.59 | Aphyric cryptocrystalline to fine-grained basaltic sheet flow |
| 1256D-30 | 84R-2 (Piece 10, 60) | 803.9 | Textural change | 3.16 | Massive aphyric fine-grained basalt |
| 1256D-31 | 85R-3 (Piece 3, 24) | 814.5 | Chilled margin | 11.27 | Massive aphyric fine-grained basalt |
| 1256D-32 | 88R-1 (Piece 9, 49) | 840.7 | Textural change | 0.93 | Aphyric fine-grained sheet flow |
| 1256D-33a | 89R-1 (Piece 1, 0) | 849.8 | Different style of eruption | 9.19 | Aphyric microcrystalline sheet flow |
| 1256D-33b | 99R-1 (Piece 1, 0) | 907.4 | Textural change (more massive and coarse grained) | 2.45 | Aphyric fine-grained basaltic sheet flow |
| 1256D-34a | 100R-1 (Piece 2, 6) | 910.7 | Breccia (containing clasts with chilled margin) | 2.72 | Massive aphyric microcrystalline to fine-grained basalt |
| 1256D-34b | 101R-2 (Piece 7, 33) | 918.8 | Rubbles, change in fracturation and alteration features | 2.49 | Massive aphyric fine-grained basalt |
| 1256D-35a | 102R-3 (Piece 6, 24) | 929.8 | Textural change | 2.71 | Aphyric cryptocrystalline to fine-grained basaltic sheet flow |
| 1256D-35b | 106R-1 (Piece 16, 67) | 929.6 | Phenocrysts (sparsely olivine-clinopyroxene-plagioclase phyric) | 0.32 | Sparsely phyric cryptocrystalline to microcrystalline sheet flow |
| 1256D-35c | 106R-1 (Piece 24, 108) | 951.1 | Return to aphyric texture | 2.14 | Aphyric cryptocrystalline to microcrystalline basaltic sheet flow |
| 1256D-36a | 108R-2 (Piece 11, 61) | 951.5 | Breccia, textural change | 3.56 | Massive aphyric microcrystalline basalt |
| 1256D-36b | 110R-1 (Piece 3, 26) | 969.9 | Textural change | 2.85 | Massive aphyric microcrystalline basalt |
| 1256D-36c | 111R-1 (Piece 2, 25) | 974.7 | Textural change | 1.39 | Massive aphyric microcrystalline basalt |
| 1256D-37 | 112R-1 (Piece 10, 75) | 980.0 | Textural change, phenocrysts (sparsely clinopyroxene-plagioclase phyric) | 0.89 | Sparsely phyric cryptocrystalline to microcrystalline sheet flow |
| 1256D-38 | 113R-1 (Piece 10, 38) | 984.4 | Breccia (containing clasts with chilled margin) | 2.15 | Aphyric microcrystalline to fine-grained sheet flow |
| 1256D-39a | 114R-1 (Piece 12, 112) | 989.9 | Mod. vesicular, breccia with cryptocrystalline clasts | 0.81 | Massive sparsely phyric moderately vesicular microcrystalline basalt |
| 1256D-39b | 114R-2 (Piece 10, 66) | 990.9 | Textural change (disappearance of vesicles) | 3.38 | Massive aphyric microcrystalline basalt |
| 1256D-40 | 117R-1 (Piece 6, 85) | 1004.1 | Textural change, brecciation | 1.67 | Cataclastic-massive basaltic unit |
| 1256D-41 | 118R-1 (Piece 8, 66) | 1008.7 | Textural change | 3.87 | Aphyric microcrystalline basaltic sheet flow |
| 1256D-42a | 122R-1 (Piece 7, 25) | 1027.6 | Textural change (volcanic breccia) | 1.30 | Mineralized volcanic breccia |
| 1256D-42b | 122R-2 (Piece 4, 30) | 1029.1 | Volcanic breccia interbedded with sheet flow | 1.47 | Mineralized volcanic breccia intercalated with aphyric cryptocrystalline basaltic sheet flow |
| 1256D-43 | 123R-1 (Piece 24, 109) | 1033.2 | Textural change | 4.40 | Aphyric microcrystalline basaltic sheet flow |
| 1256D-44a | 129R-1 (Piece 1, 0) | 1060.9 | Textural change | 1.96 | Massive aphyric microcrystalline basalt |
| 1256D-44b | 130R-1 (Piece 1, 0) | 1065.7 | Breccia, textural change | 2.34 | Massive aphyric microcrystalline basalt |
| 1256D-44c | 131R-1 (Piece 1, 0) | 1070.5 | Textural change | 4.41 | Massive aphyric microcrystalline basalt |
| 1256D-44d | 133R-1 (Piece 5, 108) | 1881.1 | Textural change | 3.54 | Massive aphyric microcrystalline basalt |
| 1256D-45 | 135R-1 (Piece 10, 101) | 1090.7 | Breccia | 2.83 | Massive aphyric microcrystalline basalt |
| 1256D-46a | 137R-1 (Piece 16, 105) | 1100.4 | Textural change | 2.24 | Massive aphyric microcrystalline basalt |
| 1256D-46b | 139R-1 (Piece 2, 8) | 1109.0 | Textural change and possible contact | 1.63 | Massive aphyric microcrystalline basalt |
| 1256D-47 | 140R-1 (Piece 4, 19) | 1113.9 | Complex brecciated intrusive contact | 0.90 | Intrusive contact breccia and aphyric fine-grained basalt |
| 1256D-48 | 141R-1 (Piece 2, 9) | 1118.6 | Brecciated chilled margin | 3.59 | Massive aphyric microcrystalline to fine-grained basalt |
| 1256D-49 | 143R-1 (Piece 12, 56) | 1128.7 | Breccia, dike contact | 0.94 | Aphyric microcrystalline basalt |
| 1256D-50 | 143R-2 (Piece 6, 22) | 1129.8 | Change of phenocryst content (olivine + clinopyroxene) | 9.61 | Massive sparsely phyric microcrystalline basalt |
| 1256D-51 | 147R-1 (Piece 5, 19) | 1145.4 | Textural change (more coarse grained) | 0.97 | Doleritic basalt |
| 1256D-52a | 148R-1 (Piece 1, 0) | 1151.1 | Textural change | 3.77 | Massive aphyric microcrystalline basalt |
| 1256D-52b | 149R-1 | — | Intrusive contact | — | Aphyric cryptocrystalline basalt |
| 1256D-52c | 151R-1 | — | Intrusive contact | — | Aphyric cryptocrystalline basalt |
| 1256D-53a | 152R-1 (Piece 1, 0) | 1169.9 | Textural change | 3.00 | Massive aphyric fine-grained basalt |
| 1256D-53b | 153R-2 | — | Intrusive contact | — | Aphyric cryptocrystalline basalt |
| 1256D-54a | 154R-1 (Piece 1, 0) | 1179.6 | Textural change | 4.68 | Massive aphyric microcrystalline basalt |
| 1256D-54b | 155R-1 | — | Intensive contact | — | Aphyric cryptocrystalline dike |
| 1256D-55a | 156R-1 (Piece 1, 0) | 1189.4 | Textural change | 6.06 | Massive aphyric microcrystalline basalt |
| 1256D-55b | 157R-1 | — | Intrusive contact | — | Aphyric microcrystalline basalt |
| 1256D-56a | 159R-1 (Piece 16, 93) | 1204.7 | Textural change | 3.94 | Aphyric cryptocrystalline to microcrystalline basalt |
| 1256D-56b | 161R-1 | — | Intrusive contact | — | Aphyric cryptocrystalline basalt |
| 1256D-57a | 162R-1 (Piece 9, 65) | 1214.0 | Textural change | 4.93 | Massive aphyric cryptocrystalline-microcrystalline basalt |
| 1256D-57b | 162R-3 | 1216.8 | Intrusive contact | — | Aphyric cryptocrystalline basalt |
| 1256D-57c | 163R-2 | 1219.7 | Textural change and intrusive contact | — | Aphyric cryptocrystalline basalt |
| 1256D-58 | 163R-3 (Piece 1, 0) | 1221.0 | Textural change | 2.83 | Massive aphyric cryptocrystalline to microcrystalline basalt |
| 1256D-59 | 164R-2 (Piece 9, 45) | 1225.0 | Textural change | 0.98 | Massive aphyric microcrystalline basalt |
| 1256D-60a | 164R-3 (Piece 3, 16) | 1226.2 | Textural change | 3.69 | Massive aphyric microcrystalline basalt |
| 1256D-60b | 165R-3 | — | Intrusive contact | — | Aphyric cryptocrystalline dike |
| 1256D-61a | 166R-1 (Piece 1, 0) | 1232.6 | Textural change | 3.56 | Massive aphyric microcrystalline basalt |
| 1256D-61b | 166R-1 | — | Intrusive contact | — | Aphyric cryptocrystalline dike |
| 1256D-62 | 167R-1 (Piece 1, 0) | 1236.4 | Textural change | 3.01 | Massive aphyric-sparsely phyric microcrystalline basalt |
| 1256D-63 | 167R-3 (Piece 11, 73) | 1239.7 | Breccia, textural change | 6.37 | Aphyric microcrystalline basalt |
| 1256D-64 | 169R-1 (Piece 9, 60) | 1247.6 | Textural change | 4.32 | Massive aphyric microcrystalline basalt |
| 1256D-65 | 170R-2 (Piece 12, 104) | 1253.4 | Textural change | 1.15 | Massive aphyric microcrystalline basalt |
Note: — = not applicable.
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