Figure F2. Basement age vs. depth of basement penetration for scientific drill holes >50 m into in situ ocean crust formed at mid-ocean ridges. Note that the boundaries between the erupted lavas, the dike-lava transition zone, and the sheeted dike complex/upper gabbro boundary are placed at arbitrary depths based loosely on Hole 504B stratigraphy. Predictions based on marine seismic reflection studies indicate that the combined thickness of the lava-dike sequences should decrease with spreading rate, but this is yet to be tested and whether it is the dikes or lavas that is thinned is so far unknown. Black lines = DSDP drill holes, blue lines = ODP drill holes, red lines = Holes 1256C and 1256D.

Figure F2. Basement age vs. depth of basement penetration for scientific drill holes >50 m into in situ ocean crust formed at mid-ocean ridges. Note that the boundaries between the erupted lavas, the dike-lava transition zone, and the sheeted dike complex/upper gabbro boundary are placed at arbitrary depths based loosely on Hole 504B stratigraphy. Predictions based on marine seismic reflection studies indicate that the combined thickness of the lava-dike sequences should decrease with spreading rate, but this is yet to be tested and whether it is the dikes or lavas that is thinned is so far unknown. Black lines = DSDP drill holes, blue lines = ODP drill holes, red lines = Holes 1256C and 1256D.