The mineralogy and chemistry of marine evaporites sets limits on excursions of the composition of sea water which may have occurred during the Phanerozoic. The permitted volume occupied by Phanerozoic sea water in log mSO4- — log mca+2. —log HCO3- space has roughly the shape of a doubly terminated pyramid. Present-day sea water lies near the center of the permitted volume. The maximum permitted concentration of all the major components in sea water is modest. This is particularly true of Ca+2 and HCO3-; the oceans have apparently been able to dispose effectively of river alkalinity during the entire Phanerozoic.
Figures & Tables
This volume represents some of the papers presented at the SEPM Research Symposium GeologicHistory of the Oceans at the Annual Meeting, March 1971, in Houston, Texas. Knowledge of oceanic sediments has been acquired in two ways: 1) directly by sampling and observation, and 2) indirectly through seismic investigations. Until the past decade, direct sampling and observation techniques could only provide information on the surficial materials of the ocean floor. The development of the piston corer has permitted oceanographic vessels to sample the upper 20 meters, and more recently the upper 30 meters, of the ocean floor, but such cores rarely penetrate the Pleistocene and enter older sediments. Until recently, most knowledge of the deeper sedimentary materials in the ocean basins was obtained through seismic reflection studies. The purpose of this volume is to present a number of observations, ideas, interpretations, and speculations which will be of value in considering the meaning of the increasing volume of data from older deep sea deposits.