Abstract

Drilling and coring by JOIDES consists of over 150 stations in the world oceans including coring beneath water depths in excess of 20,000 feet, sub-bottom penetration of over 3,000 feet, and re-entry of the drill hole beneath 13,000 feet of water. Oil was discovered beneath 11,700 feet of water in the Gulf of Mexico and other cores have supplied supporting evidence for concepts of sea floor spreading, and plate tectonics as derived from bathymetry, geomagnetism, earthquake seismology and tectonic events recorded by the rocks an land.

Evidence is accumulating that the ocean basins are geologically young (less than 200 million years); that new oceanic lithosphere forms along crests of oceanic ridges; that older oceanic lithosphere is resorbed beneath linear trends of deep focus earthquakes associated with oceanic trenches; that extensive plates of the earth's lithosphere move laterally at rates up to several inches per year; that these plates interact to cause deformation, mountain building, and unconformities; and although the areal extent of continental material may be increasing on balance, the distribution of land and sea may be a passive and ephemeral consequence of interactions between adjacent plates of lithosphere.

The practical consequences of these concepts may lie in the potential for reconstruction of land-sea relationships of the past and thereby the distribution of sediment along continental margins of the past and present; the potential for predicting structural style resulting from plate divergence, convergence and oblique interaction; and the effects of abnormal temperature in the generation of petroleum.