Organics/marine shell samples

Table I. Paired Terrestrial Organics/Marine Shell Samples from the West Coast of North America...

Foraminifera are also important in marine geochemistry studies, and Li isotopes have been measured in the shells of a variety of these organisms. The first report of this kind (You and Chan 1996) gave data for four Pleistocene samples of H obliquiloculata 5 Li = +19.3 to +23.0 for two glacial period samples and +26.6 to +42.4 for two interglacial samples (data without blank correction). The species effect interpreted by Marriott et al. (2004) in corals has also been suggested for forams. In the study of Rosier et al. (2001), core-top (i.e., Holocene)P. obliquiloculata samples yielded isotopic compositions close to modem seawater (5 Li = +27.8 to +31.1), whereas samples of G. tumida from the same samples had values of up to +50.5. 

Boron can be extracted from natural or synthetic calcium carbonate (or other geologic materials) before analysis by mass spectrometry. The extraction method depends on the analytical technique to be used. For any method, natural samples (typically foraminifera, a single-celled marine invertebrate whose shells accumulate in ocean sediments) must be cleaned of organic matter. This is... 

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