Strontium Isotope Stratigraphy of Early Cretaceous Rudist Bivalves
Published:January 01, 2007
Jean-Pierre Masse, Thomas Steuber, 2007. "Strontium Isotope Stratigraphy of Early Cretaceous Rudist Bivalves", Cretaceous Rudists and Carbonate Platforms: Environmental Feedback, Robert W. Scott
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The trace-element content and strontium isotope ratio have been determined for twelve requienid rudists from SE France. Fromthese data the seawater ratio of eight stratigraphic intervals was determined. The biostratigraphy of the associated platform carbonates, ranging from Berriasian to Lower Aptian, was derived from shallow-water benthic organisms, including calcareous algae (Dasycladales), large foraminifera (mainly Orbitolinidae), and rudists. Isotope ratios of well preserved rudist shells were compared to secular variationsof the 87Sr/86Sr ratio of seawater as derived from belemnites and calibrated to the Boreal ammonite zonation (McArthur et al., 2001).Stratigraphic mismatches between the values measured on requieniid rudists and the Boreal Sr-isotope reference curve appear to resultmainly from the fact that the reference curve is resolved rather as a band. A few larger discrepancies may be due to weaknesses in the original correlation of biostratigraphic markers and isotope values for some time intervals (e.g., upper Barremian).
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Cretaceous Rudists and Carbonate Platforms: Environmental Feedback
Sedimentologists, stratigraphers and paleontologists will find new data in SP 87, "Cretaceous Rudists and Carbonate Platforms: Environmental Feedback". The papers of the Proceedings of the Seventh International Congress on Rudists are organized into three themes: (1) Depositional Environments of Cretaceous Carbonates has been an overarching theme of the Working Group on Cretaceous Carbonate Platforms, Study of rudists, which produced great volumes of carbonate sediment, is central to understanding processes and reservoir prediction. Some of the world's great hydrocarbon reservoirs are rudist debris beds. (2) The Origins, Events, and Demise of Rudist Paleocommunities signal significant local and even global events in Earth systems. Rudist communities responded to oceanic anoxic events and to complex factors that lead to oxygenation of deep ocean water masses. (3) Theme Towards Rudists Taxonomy, Biogeography, and Phylogeny focuses on the paleobiology and systematics of rudists. The foundation of all interpretations of biogeography and paleoecology is solid taxonomy that is agreed upon by the majority of specialists. This is a core, ongoing scientific pursuit.