Figure F13. Boreholes >200 m deep drilled into in situ ocean crust by DSDP, ODP, and IODP compared to Hole 1256D. Hole 504B is the only other basement hole to sample a complete extrusive sequence and penetrate into the sheeted dikes. ODP Hole 735B and IODP Hole U1309D, which drilled deeply into gabbros tectonically exposed near ridge-transform intersections on the Southwest Indian Ridge and Mid-Atlantic Ridge, respectively, are shown for comparison. L.p. = lava pond, Inflate = inflated flows, Sheet and mass flows = sheet and massive flows, T.z. = transition zone, Gb = gabbroic rocks, S. intru = sheeted intrusives. msb = meters subbasement. See Table T2 for description and basis for these subdivisions.
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