ABSTRACT

From consideration of the volumes of halite and associated salts deposited since the Permian, one must infer that either: 1) sea water at the close of the Paleozoic was hypersaline relative to seas of today (35 Salinity); or 2) while 6,000,000 + cu. km. of salts have been precipitated from the world ocean in highly varying amounts at irregular intervals xince the Permian, an equal volume of salts have gove into solution. Data from analysis of sedimentary sulfur-isotope ratios strongly support the former inference. Concording, but more speculative, support also is available from aridity indices.

A condition of hypersalinity in the oceans of the Permian world would explain the known patterns of Permian extinctions with peculiar satisfaction. The evidence suggests that those marine taxa (e.g., echinoderms, fusulines, coelenterates) with the lowest tolerance for salinity variability were precisely the group within the entire Permian biota that suffered the greatest proportion of extinctions at the close of the Paleozoic. Such an explanation is more consistent with a uniformitarian Earth than causes sought in cosmic radiation variability or pulses, which should have affected terrestrial organisms more strongly than marine taxa.

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