One hundred and sixty-eight North American shales, ranging in age from Proterozoic to Cretaceous, have been analyzed for boron; analyses for CO2 permitted corrections to a carbonate-free basis. The B values mostly agree with the inferred salinities of the environments of deposition, based on geological evidence: anomalously low values in the Devonian Littleton formation may be correlated with loss of B to regional quartz–tourmaline veins.The data do not permit drawing any inference regarding secular variations in oceanic B content.A review of recent work on B sedimentary geochemistry indicates the need for analyses of real, rather than hypothetical, mineral phases.

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