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Science 22 April 1994:
Vol. 264. no. 5158, pp. 546 - 550
DOI: 10.1126/science.264.5158.546
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Articles

Strontium Isotopic Composition of Mid-Cretaceous Seawater

B. Lynn Ingram 1, Rodolfo Coccioni 2, Alessandro Montanari 3, and Frank M. Richter 4

1 Department of Geology and Geophysics, University of California, Berkeley, CA 94720, USA.
2 Instituto di Geologia, Via Santa Chiara 27, 61029 Urbino, Italy
3 Osservatorio Geologico di Coldigioco, 62020 Frontale di Apiro (MC), Italy
4 Department of Geophysical Sciences, University of Chicago, Chicago, IL 60637, USA.

The 87Sr/86Sr ratio in fish teeth separated from mid-Cretaceous marl and black shale from the northeastern Apennines and Venetian Alps (Italy) define three periods of low 87Sr/86Sr ratio at 121 to 124 million years ago (Ma), 110 to 115 Ma, and 89 to 91 Ma. The 87Sr/86Sr excursions correspond to oceanic anoxic events represented by the Livello Selli, Livello 113, Livello Urbino, and Livello Bonarelli black shale marker beds and probably reflect an increase in the low-87Sr/86Sr hydrothermal strontium flux associated with the emplacement of the Ontong-Java and Kerguelen plateaus (120 to 110 Ma) and the Caribbean Plateau (89 to 91 Ma). The modeled flux is consistent with the volumes and eruption rates of the oceanic plateaus but is far smaller than expected from the proposed Cretaceous crustal production rates of 50 to 100 percent greater than modern.

Submitted on December 17, 1993
Accepted on March 15, 1994


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Modelling oceanic carbon and phosphorus fluxes: implications for the cause of the late Cenomanian Oceanic Anoxic Event (OAE2).
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Cretaceous strontium isotope stratigraphy using marine barite.
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A Time Frame for Construction of the Kerguelen Plateau and Broken Ridge.
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J. Petrology 43, 1109-1119
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Seawater Strontium Isotopes, Oceanic Anoxic Events, and Seafloor Hydrothermal Activity in the Jurassic and Cretaceous.
C. E. Jones and H. C. Jenkyns (2001)
Am J Sci 301, 112-149
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Oceanic minerals: Their origin, nature of their environment, and significance.
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PNAS 96, 3380-3387
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Strontium Isotopes in Mid-Cretaceous Seawater.
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Science 266, 1584-1585
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