Study of 12 carbonate oozes from Deep Sea Drilling Project Hole 463, in the Mid-Pacific Mountains, suggests mean values of 0.70690 ± 0.00029 (2-sigma) and 0.70712 ± 0.00030 (relative to 0.71014 for the NBS 987 Sr isotope standard) as representing the Sr isotope composition of the Barremian and early Aptian seas, respectively. Two additional values of less than 0.7064 are the least radiogenic values known from the Phanerozoic and may be a consequence of the introduction of Sr depleted in the heavy isotope from massive submarine volcanic activity, which followed the initiation of the latest oceanic spreading episode in the Oxfordian.

Supplement to: Clauer, Norbert (1981): 87Sr/86Sr ratios of the Barremian and early Aptian Seas. In: Thiede, J; Vallier, TL; et al. (eds.), Initial Reports of the Deep Sea Drilling Project (U.S. Govt. Printing Office), 62, 781-783