Atlantic Ocean benthic foraminifera

Several decades ago it was realized that chemistry of the shells of benthic foraminifera (carbon isotope and Cd/Ca ratios) carried an imprint of the nutrient content of deep-water masses (Shackleton, 1977 Broecker, 1982 Boyle, 1981). This led rapidly to the recognition that the water masses in the Atlantic Ocean were arrayed differently during the last glacial maximum than they are today, and the hypothesis that the glacial arrangement reflected a diminished contribution of low-nutrient North Atlantic deep water (NADW) (Curry and Lohmann, 1982 Boyle and Keigwin, 1982). More detailed spatial reconstructions indicated a shallow nutrient-depleted water... 

Figure 7 Modern and LGM distributions of in the Atlantic Ocean inferred from benthic foraminifera (Cibicidoides) (Laheyrie, 1992) (reproduced by permission of Elsevier from Quat. Sci. Rev., 1992, 11, 401-413).

Mackensen, A. Licari, L. 2004. Carbon isotopes of live benthic foraminifera from the eastern South Atlantic Ocean sensitivity to bottom water carbonate saturation state and orgnaic matter rain rates. In Wefer, G., Mulitza, S. Ratmeyer, V. (eds) The South Atlantic in the Late Quaternary - Reconstruction of Material Budget and Current Systems. Springer-Verlag, Berlin, Heidelberg, 623 -644. 

Figure 12. Sedimentary and geochemical records from oceans, showing dramatic transient shifts in most records in an interval from just before 8 Ma to 4 Ma (shaded), from Filippelli (1997b). Symbols in all records represent averages of 1 Myr intervals, except for normalized sediment flux curve, which represents 0.5 Myr averages. After interval averaging, all records were adjusted to time scale of Cande and Kent (1992) for consistency, (a) Normalized sediment flux in northern Indian Ocean (Rea 1992). (b) Ge/Si ratio in opaline silica from diatoms (Shemesh et al. 1989). (c) of bulk marine carbonates (Shackleton 1987). Although details of different carbon isotope records differ, general trends revealed in this low-resolution record are robust. PDB is Pee Dee belemnite. (d) Phosphorus accumulation rates in equatorial Pacific (Filippelli and Delaney 1994). Peak in accumulation rates is also observed in other parts of Pacific (Moody et al. 1988) and western Atlantic (Delaney and Anderson 1997). These peaks are linked with increased phosphorus input rates from continental weathering (e.g., Filippelli and Delaney 1994). (e) Sr/ Sr record from marine carbonates (Hodell et al. 1990, 1991). (f) of benthic foraminifera (Miller et al 1987).

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