Benthic foraminifera

Guber, A.L. and Ohmoto, H. (1978) Deep sea environments of Kuroko formation as indicated by the benthic foraminifera from the Hokuroku district, Japan. Mining Geology, 28, 245-256. 

Fig. 4.1. Isotopic paleotemperature analyses of planktonic and benthic foraminifera from the sub-Antarctic Pacific indicating considerably warmer conditions in the Early Cenozoic (Shackleton and Kennett, 1975a).

In order to provide AMS analyses to the broad ocean sciences research community, the National Ocean Sciences Accelerator Mass Spectrometry Facility (NOSAMS) was established at Woods Hole Oceanographic Institution (Massachusetts) in 1989. Studies performed there include identification of sources of carbon-bearing materials in the water column and sediment, dating of sedimentary samples, investigations of paleocirculation patterns (e.g., from observations of differences in 14C relative abundances in planktonic and benthic foraminifera, and coral cores and cross sections), as well as studies of modern oceanic carbon cycling and circulation. In fact, much that is known about advective and diffusive processes in the ocean comes from measurements of chemical tracers, such as 14C, rather than from direct measurements of water mass flow. 

Planktonic foraminifera and cocolithophores are composed of low magnesian calcite (< 1 mol % MgC03). Benthic foraminifera are formed of either aragonite or high magnesian calcite. Pteropods are the most abundant aragonite organisms. 

Delaney, M., and E. A. Boyle (1987), "Cadmium/Calcium in Late Miocene Benthic Foraminifera and Changes in the Global Organic Carbon Budget", Nature 330, 156-159. 

Manceau A, Schlegel ML, Musso M, Sole VA, Gauthier C, Petit PE, Trolard F (2000) Crystal chemistry of trace elements in natural and synthetic goethite. Geochim Cosmochim Acta 64 3643-3661 Marchitto Jr. TM, Curry WB, Oppo DW (2000) Zinc concentrations in benthic foraminifera reflect seawater chemistry. Paleoceanogr 15 299-306. 

Fig. 3.44 5 C values of benthic foraminifera species. The 5 C value for the dissolved bicarbonate in deep equatorial water is shown by the vertical line (after Wefer and Berger 1991)...

C-values in planktonic and benthic foraminifera can be used to monitor CO2 variations in the atmosphere by measuring the vertical carbon isotope gradient, which is a function of the biological carbon pump. This approach was pioneered by Shackleton et al. (1983), who showed that enhanced contrast between surface waters and deeper waters was correlated with intervals of reduced atmospheric CO2 contents. Increased organic carbon production in surface waters (possibly caused by enhanced nutrient availability) leads to the removal of carbon from surface waters, which in turn draws down CO2 from the atmospheric reservoir through re-equilibration. 

Reconstructions of pathways of deep-water masses in the North Atlantic during the last 60,000 years have been performed by analyzing high resolution records of benthic foraminifera Cibicides wuellerstorfi as this species best reflects changes in the chemistry of bottom waters (Duplessy et al. 1988 Samtheim et al. 2001). The initial 5 C-signature of North Atlantic Deep Water (NADW) is 1.3-1.5%c. As... 

For the period prior to the first onset of Antarctic glaciation (around 33 Ma), oxygen isotope variations in global benthic foraminifera records reflect temperature... 

Variations in the benthic foraminifera record after 33 Ma indicate fluctuations in global ice volume in addition to temperature changes. Since then the majority of the 5 0 variations can be attributed to fluctuations in the global ice volume. Thus, Tiedemann et al. (1994) demonstrated the presence of at least 45 glacial-interglacial cycles over the last 2.5 Ma. 

Unfortunately, equations (3.19) and (3.20), although the best currently available for the data, can only be considered tentative. The weakness lies in the temperature dependence. As mentioned earlier, it is not known whether the results reflect a temperature dependence or a change in the proportion of aragonite to calcite. Another shortcoming in this relationship is that the temperature range of the experiments, 20° to 63°C (if Baertschi s data are included), is well above the temperature at which many organisms secrete carbonate. Because benthic foraminifera have proved very useful in carbon isotopic studies, it is important to have carbon isotopic equilibrium defined over their temperature range. 

Figure 10.20. Comparison of some trends through the Cenozoic. A. The 8180 content of benthic foraminifera (Savin et al., 1975 see also Prentice and Matthews, 1988). If the 5180 trend is primarily due to temperature, Cretaceous deep water temperatures were about 12°C warmer than today. B. Progressive change of the North Atlantic and Pacific carbonate compensation depth (CCD van Andel, 1975). C. The Sr/Ca ratio of planktonic foraminifera (Graham et al., 1982). D. Ridge volume (Pitman, 1978).

Boyle E.A. (1986) Paired carbon isotope and cadmium data from benthic foraminifera Implications for changes in oceanic phosphorous, oceanic circulation, and atmospheric carbon dioxide. Geochim. Cosmochim. Acta 50, 265-276. 

Grossman E.L. (1984) Carbon isotopic fractionation in live benthic foraminifera -comparison with inorganic precipitate studies. Geochim. Cosmochim. Acta 48, 1505-1512. 

Grossman E.L. and Ku T.L. (1981) Aragonite-water isotopic paleotemperature scale based on the benthic foraminifera Hoeglundina elegans. Geol. Soc. America Abstracts with Programs 13, 464. 

Hester K. and Boyle E. (1982) Water chemistry control of cadmium content in recent benthic foraminifera. Nature 298, 260-262. 

Izuka S.K. (1988) The variation of magnesium concentration in the tests of recent and fossil benthic foraminifera. Ph.d. dissertation, Univ. of Hawaii. 

Sen Gupta, B.K., and Machain-Castillo, M.L. (1993) Benthic foraminifera in oxygen-poor habitats. Mar. Micropaleontol. 20, 183-210. 

Sen Gupta, B.K., Turner, R.E., and Rabalais, N.N. (1996) Seasonal oxygen depletion in continental-shelf waters of Louisiana Historical record of benthic foraminifera. Mar. Geol. 24, 227-230. 

Mg-calcite Coralline (red) algae Benthic foraminifera Echinoderms Serpulids (tubes)... 

Lea D. W. and Boyle E. (1989) Barium content of benthic foraminifera controlled by bottom water composition. Nature 338, 751-753. 

Following Emiliani s (1955) discovery, other laboratories established the capability to apply oxygen isotope variations to oceanic temperature history. It is worth a brief mention of two further major advances relevant to Urey s original conception. In 1967, Nicholas Shackleton of Cambridge University reported the first systematic down-core variations in benthic foraminifera (Shackleton, 1967). He argued that benthic fauna, because they lived in the near-freezing bottomwaters of the ocean, would mainly record... 

Billups K. and Schrag D. P. (2002) Paleotemperatures and ice volume of the past 27 Myr revisited with paired Mg/Ca and measurements on benthic foraminifera. 

Duplessy J. C., Lalou C., and Vinot A. C. (1970) Differential isotopic fractionation in benthic foraminifera and paleotemperatures reassessed. Science 168, 250-251. 

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