Sea carbonate

Fig. 5-1. Settling particles of biological origin carry carbon and alkalinity into the deep sea. Carbonate equilibrium reactions in the surface sea affect the atmospheric pressure of carbon dioxide.

The calcium carbonate shells of marine microfauna are a large repository of terrestrial calcium and constitute a potential record of changes in the cycling of calcium at and near the earth s surface (Zhu and MacDougall 1998 De La Rocha and DePaolo 2000 Schmitt et al. 2003a,b). To understand the record held in deep sea carbonate sediments, it is necessary to document any Ca isotopic fractionation that occurs between dissolved seawater Ca and carbonate shell material. 

Pichat S, Douchet C, Albarede F (2003) Zinc isotope variations in deep-sea carbonates from the eastern equatorial Pacific over the last 175 ka. Earth Planet Sci Lett 210 167-178 Price NM, Morel EMM (1990) Cadmium and cobalt substitution for zinc in a zinc-deficient marine diatom. Nature 344 658-660... 

Submarine lithification and precipitation of cements in deep sea carbonate sediments are relatively rare processes in typical major ocean basin sediments. Milliman and his associates have summarized much of the information on these processes (Milliman, 1974 Milliman and Muller, 1973,1977). The cements are of both aragonitic and magnesian calcite mineralogies, and are largely restricted to shallow seas such as the Mediterranean and Red seas, and sediments in the shallower parts of major ocean basins in which biogenic aragonite is also present. The formation of carbonate cements will be discussed in detail in subsequent chapters. 

Rapid increases in the interstitial water concentrations of dissolved strontium with increasing burial depth of deep-sea carbonate sediments have been interpreted as evidence of the recrystallization reaction (Baker et al., 1982 Elderfield et al., 1982 Gieskes, 1983). Figure 8.17 shows an example of interstitial-water profiles of dissolved alkaline-earth species from a carbonate nanno-fossil ooze from the Ontong Java Plateau (DSDP site 288 5°58 S, 161°50 E). At this site calcium and magnesium concentrations are linearly correlated, and their gradients are governed by chemical reactions deep in the sediment column. 

Finally, this tripartite cyclicity is also seen in the frequency of occurrence of Phanerozoic ironstones and oolites (Figure 10.18). As sea level withdrew from the continents and continental freeboard increased, shallow-water areas with the requisite environmental conditions necessary to form oolite and ironstone deposits decreased in extent. Thus, as calcium carbonate deposidon increased on slopes and in the deep sea, carbonate oolite and ironstone deposition on shelves and banks nearly ceased. 

Adelseck C.G. Jr. (1978) Dissolution of deep-sea carbonate preliminary calibration of preservational and morphological aspects. Deep-Sea Res. 25, 1167-1185. 

Adelseck C.G., Jr. and Berger W.H. (1975) On the dissolution of planktonic foraminifera and associated microfossils during settling and on the sea floor. In Dissolution of Deep-Sea Carbonates (eds. A. Be and W. Berger), pp. 70-81. Cushman Foundation for Foraminiferal Research, Special Publication 13, W. Sliter. 

Baker P.A. and Bloomer S.H. (1988) The origin of celestite in deep-sea carbonate sediments. Geochim. Cosmochim. Acta 52,335-340. 

Berger W.H. (1977) Deep-sea carbonate and the deglaciation preservation spike in pteropods and foraminifera. Nature 269, 301-304. 

Berger W.H. (1978) Deep-sea carbonate Pteropod distribution and the aragonite compensation depth. Deep-Sea Res. 25,447-452. 

Berger W.H. and Vincent E. (1986) Deep-sea carbonates Reading the carbon-isotope signal. Geologische Rundschau 75, 249-269. 

Elderfield H., Gieskes J.M., Baker P.A., Oldfield R.K., Hawkesworth C.J. and Miller R. (1982) 87Sr/86Sr and 180/160 ratios, interstitial water chemistry and diagenesis in deep-sea carbonate sediments of the Ontong Java Plateau. Geochim. Cosmochim. Acta 46, 2259-2268. 

Honjo S. (1975) Dissolution of suspended coccoliths in the deep-sea water column and sedimentation of coccolith ooze. In Dissolution of Deep-Sea Carbonates (eds. W. Sliter, A.W.H. Be and W.H. Berger) pp. 115-128. Cushman Found. Foraminiferal Res., Spec. Publ. No. 13. 

Zeff, M. L. Perkins, R. D. (1979). Microbial alteration of Bahamian deep-sea carbonates. 

Richter F. M. and Liang Y. (1993) The rate and consequences of Sr diagenesis in deep-sea carbonates. Earth Planet. Sci. Lett. 117, 553-565. 

Almost all deep-sea carbonate-rich sediments are composed of calcite low in magnesium (> 99% CaCOa). This material is primarily derived from pelagic skeletal organisms. Coccolithophores... 

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