Biogenic carbonate

Preservation of Biogenic Carbon Isotopic Signals in Plio-Pleistocene Bone and Tooth Mineral... 

Comparing rural with "typical" urban samples (2nd entry, Table 5), we find that fossil carbon predominates in the urban particulate matter, and the converse. A significant amount of biogenic carbon is found in the urban samples (even in the absence of wood burning), however and this may be related to vegetative emissions. For example, besides fossil fuel indicators such as... 

Walter and Morse (1984) were able to document the relative importance of microstructure for the dissolution of biogenic carbonates. Biogenic magnesian calcites are structurally disordered and chemically heterogeneous. Both these factors play a role in the reactivity of these minerals in natural systems. 

Hoefs J, Sywall M (1997) Lithium isotope compositions of Quaternary and Tertiary biogene carbonates and a global lithium isotope balance. Geochim Cosmochim Acta 61 2679-2690 Hogan JF, Blum JD (2003) Boron and lithium isotopes as groundwater tracers a study at the Fresh Kills Landfill, Staten Island, New York, USA. Applied Geochem 18 615-627 Huh Y, Chan LH, Edmond JM (2001) Lithium isotopes as a probe of weathering processes Orinoco River. Earth Planet Sci Lett 194 189-199... 

Catanzaro EJ, Murphy TJ, Garner EL, Shields WR (1966) Absolute isotopic abundance ratios and atomic weight of magnesium. J Res Natl Bur Stand 70A 453-458 Chang VT-C, Makishima A, Belshaw NS, O Nions RK (2003) Purification of Mg from low-Mg biogenic carbonates from isotope ratio determination using multiple collector ICP-MS. J Anal At Spectrom 18 296-301... 

A global map of quartz abundance is given in Figure 14.12. In this case, the contribution of quartz is presented as the contribution to the bulk sediment from which biogenic carbonate and silica have been removed. This map is very similar to the global distribution of dust presented in Figure 11.4, reflecting the importance of aeolian transport for this detrital silicate. 

These shallow-water deposits were the sole source of biogenic carbonate until the evolution and proliferation of planktonic calcifiers, namely the coccolithophorids and the foraminiferans, around 250mybp. This enabled a shift in the site of sedimentary carbonate acciunulation from the shallow waters to the deep sea. At present, about half of the sedimentary carbonates are being buried on the shelves and the other half in the deep sea and slopes. 

The chemical weathering of crustal rock was discussed in Chapter 14 from the perspective of clay mineral formation. It was shown that acid attack of igneous silicates produces dissolved ions and a weathered solid residue, called a clay mineral. Examples of these weathering reactions were shown in Table 14.1 using CO2 + H2O as the acid (carbonic acid). Other minerals that undergo terrestrial weathering include the evaporites, biogenic carbonates, and sulfides. Their contributions to the major ion content of river water are shown in Table 21.1. 

The sulfete and chloride minerals in evaporites (gypsum, anhydrite, halite) undergo congruent dissolution to produce Ca (aq), S04 (aq), Na (aq), and Cl (aq). The dissolution of evaporite and biogenic carbonates (limestone, dolomite, and calcite) generates... 

For oxygen this means a decrease in from an initial 5-valne very near 0%c (ocean water) to abont -2%o at depths aronnd 200 m (Perry et al. 1976 Lawrence and Gieskes 1981 Brnmsack et al. 1992). Even lower 5 0-values of about -4%c at depths of around 400 m have been observed by Matsumoto (1992). This decrease in 0 is mainly dne to the formation of anthigenic 0-enriched clay minerals such as smectite from alteration of basaltic material and volcanic ash. Other diagenetic reactions inclnde recrystallization of biogenic carbonates, precipitation of... 

Stange G. (1996) Sensory and behavioural responses of terrestrial invertebrates to biogenic carbon dioxide gradients. In Advances in Bioclimatology Vol. 4, ed. G. E. Stanhill, pp. 223-253. Springer Verlag, Berlin. 

The solid carbonate can also present several potential difficulties in solubility studies. These can be broken down into two major areas heterogeneity in composition, and excess free energy associated with lattice strain or defects and surface free energy. The problem of solid heterogeneity presents itself in most sedimentary carbonates, and is especially important in biogenic carbonates such as magnesian calcites. The problem of lattice strain and high defect density is most... 

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