Carbonates detrital

Dissolved Organic Carbon Detrital Energetics, Metabolic Regulators, and Drivers of Ecosystem Stability of Aquatic Ecosystems ... 

Wetzel, R.G (2003) Dissolved organic carbon detrital energetics. Metabolic regulators, and drivers of ecosystem stability of aquatic ecosystems. In Aquatic Ecosystems Interactivity of Dissolved Organic Matter (Findlay, S.E.G, and Sinsabaugh, R.L., eds.), pp. 455 175, Academic Press, New York. 

The detrital rain of carbon-containing particles can be divided into two groups the hard parts comprising calcite and aragonite and the soft tissue containing organic carbon. The composition of the soft tissue shows surprising... 

Fig. 11-12 Detrital carbon dynamics for the 0-20 cm layer of chernozem grassland soil. Carbon pools (kg C/ m ) and annual transfers (kg C/m per year) are indicated. Total profile content down to 20 cm is 10.4 kg C/m. (Reproduced with permission from W. H. Schlesinger (1977). Carbon balance in terrestrial detritus, Ann. Rev. Ecol. Syst. 8,51-81, Annual Reviews, Inc.)...

The two prime mechanisms of carbon transport within the ocean are downward biogenic detrital rain from the photic zone to the deeper oceans and advection by ocean currents of dissolved carbon species. The detrital rain creates inhomogeneities of nutrients illustrated by the characteristic alkalinity profiles (Fig. 11-9). The amount of carbon leaving the photic zone as sinking particles should not be interpreted as the net primary production of the surface oceans since most of the organic carbon is recycled... 

As an example, imagine a carbonate-rich sediment that contains a small but significant fraction of detrital silicate. The sediment might be a lake sediment, a surface coral, a deep-sea coral, a carbonate-rich bank sediment, or a speleothem (see for example, Richards and Dorale 2003). The carbonate has a very high U/ Th ratio (on the order of 10" by atom) and the detrital material has a lower %/ Th ratio of about 10°. The carbonate and detrital materials each have specific values that differ from each... 

Initial °Th and Pa are generally considered to be associated with a detrital component that becomes cemented, or occluded, within the speleothem. This component may be composed of clays, alumino-silicates or Fe-oxyhydroxides (Fig. 3) with strongly adsorbed and Pa. Th and Pa incorporated in speleothems and similar deposits may also have been transported in colloidal phases (Short et al. 1998 Dearlove et al. 1991), attached to organic molecules (Langmuir and Herman 1980 Gaffney et al. 1992) or as carbonate complexes in solution (Dervin and Faucherre 1973a, b Joao et al. 1987). 

Sayles FL, Martin WR, Chase Z, Anderson RF (2001) Benthic remineralization and burial of biogenic Si02, CaCOs, organic carbon and detrital material in the Southern Ocean along a transect at 170° west. Deep-Sea Research II 48 4323-4383... 

Because there is no natural mechanism for producing isotopically pure Th, any measurable Th in a sample for °Th/U dating implies the presence of at least some °Th when the sample (mineral or mineral assemblage) was formed. This initial °Th must then be subtracted from the total measured °Th before a valid °Th/U age can be calculated. In addition, a correction for initial U isotopes is required when the material being dated is a mechanical mixture of an isotopically homogeneous detrital material with an initially thorium-free mineral such as chemically precipitated carbonate. In these cases we are usually interested only in the time of formation of the Th-free material, and so must also subtract the detrital and before calculating the °ThAJ age. 

The basement is made up of crystalline schists of the meso-metamorphic Somes Series. Sedimentation started during Permian with detritic deposits interbedded with rhyolites. The overlying Triassic deposits are unconformable and include detritic formations (Lower Triassic) and massive layers of carbonate rocks (Middle Triassic). The absence of the Upper Triassic is due to the uplift of the region during the Kimmeric tectonic phase. 

An estimate of the amoimt of organic matter respired since a water mass was last at the sea surfece can be inferred from its AOU and the stoichiometry given in Eq. 8.4. The respiration of 1 mol of POM comprised of average detrital plankton biomass requires the oxidation of 106 mol organic carbon. As per Eq. 8.6, this requires 106 mol O2 ... 

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. 

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