87Sr/86Sr composition of evaporitic carbonates and sulphates from Miocene sediment cores in the Mediterranean Sea (D.S.D.P., Leg 13)



    1. Centre de Sédimentologie et Géochimie de la Surface, Institut de Géologie de l'Université Louis Pasteur,1, rue Blessig—67084 Strasbourg Cédex, France
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The 87Sr/86Sr ratios of evaporitic carbonates and sulphates from Miocene sediment cored in the Mediterranean Sea show a depletion of 87Sr when compared to the isotopic composition of the Miocene contemporaneous marine strontium: 0.70803 versus 0.70936. The arrival into the evaporitic environment of strontium brought by continental waters can explain this difference.

The variation of the 87Sr/86Sr ratios is, nevertheless, noticeable only when the influence of the continental waters is already well marked. This is proved when one compares the results obtained with strontium, to the results of isotopic analysis made on oxygen, carbon, sulphur and hydrogen taken from the same samples.