Simon F. Mitchell, James D. Ball, Stephen F. Crowley, Jim D. Marshall, Christopher R. C. Paul, Cornelis J. Veltkamp, Ashraf Samir; Isotope data from Cretaceous chalks and foraminifera: Environmental or diagenetic signals?. Geology ; 25 (8): 691–694. doi: https://doi.org/10.1130/0091-7613(1997)025<0691:IDFCCA>2.3.CO;2
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Scanning electron microscopy of sediments, microfossils, and polished thin sections from the Cenomanian-Turonian boundary section at Dover, England, demonstrates that cement is concentrated within large pores such as foraminifera and calcispheres, whereas the surrounding coccolith-rich sediments are largely lacking in cement. Isotope analysis of single microfossils and cement samples indicates the presence of mixing lines between primary (paleoceanographic) compositions and cements. Consequently, paleoceanographic and stratigraphic interpretations of these sediments, and perhaps other similar sediments based on similar data, may be suspect.