Shell debris

Thermal insulation on snow can be loose fill, sheets and roof like structures. Loose fill insulation is different types of wood chips, rice shell, debris (mineral particles), etc. Sheets can be both plastic and filled tarpaulins, e.g. with straw. Superstructures are more or less rigid constructions that are partly or totally removed/opened during the winter. 

Fig. 1 The oxygen isotopic composition of carbonate mollusk shells from the Aral Sea [15]. (1) clayey mud (2) clayey-silty mud (3) sand (4) marine shell debris (5) freshwater shell debris (6) peat (7) plant debris (8) gypsum (9-10) boundaries [(9) gradual (10) sharp)] (11-12) stages [(11) transgressive (12) regressive)]...

Fig. 3 Stratigraphic scheme of the upper Quaternary and Holocene deposits of the Aral Sea (according to [16]). (1) Clayey mud (2) silty-clayey mud (3) clay (4) sand (5) rubble (6) marine shell debris (7) freshwater shell debris (8) peat (9) plant dehiis (10) gypsum (11) sharp contacts (12) gradual contacts...

Dissolution of shell debris in sediments. Analysed unaltered shell material from marine sandstones in the northern North Sea has 6 C values close to 0%o (e.g. Macaulay et al.. 1993). 

Silt-clay, sand present, fecal-pelleted surface S30% CaCO, shell debris present in massive layers Silt-clay, sand pockets at depths a I m fecal-pelleted surface slO% CaCOj shell debris present in discrete, thin layers... 

Silt-clay, thin sand layers present fecal-pelleted surface s5% CaCOs shell debris absent or very scattered... 

Fig. 4. X radiograph of vertical sediment section at FOAM. The upper 10-12 cm are characterized by abundant shell debris. A laminated layer at 4 cm is disrupted irregularly by shells and biogenic reworking activity. Parts of two vertical maldanid tubes can be seen in the center at a depth of 8-10 cm. Below 10-12 cm, the sediment begins to become laminated. This laminated zone begins at 8 cm in most x radiographs from FOAM (see Fig. 5). (Scale 3 cm.)...

Fig. 8. X radiograph of 5-cm-thick horizontal slab of sediment 10-15 cm deep from NWC. The irregular distribution of shell debris can be seen with most shell material restricted to the right side of the radiograph. Remnants of maldanid tubes can be made out as can a single layer crustacean burrow (left) passing vertically down into the sediment. Maldanids are not presently a common, permanent faunal component at NWC but occur irregularly. (Scale 3 cm.)...

Fig. 10. Vertical x radiograph from DEEP. Maldanid dwelling tubes are abundant on right side. These commonly extend 20 cm into sediment. Shell debris is generally absent below a few centimeters. Where dwelling burrows are absent the sediment is characterized by a mottled, bioturbate texture (right side). (Scale 3 cm.)...

DEEP also lacks evidence of many sedimentary structures formed by physical processes. Dwelling burrows, often at high abundance, extend great distances into sediment and are characteristic of this station (Figs. 10 and 11). Despite the presence of living shell-bearing animals at DEEP (see also Saunders, 1956), little shell debris is preserved. 

The impurities which may adversely affect the strength and durability of concrete are fines (clay, silt and dust), chlorides, shell debris, organic matter, sulfates, chalk, mica, pyrites and other metallic impurities. 

Shell debris in marine and coastal aggregate deposits is acceptable in concrete, providing it does not contain excessive numbers of whole shells with inaccessible voids. 

Figure 32.5 Brachiopod shell debris as a percentage of the total skeletal debris is the Rapla section of the North Estonian Confacies belt (right) and the Engure section in the Livonian Tongue (left) (data modified from Polma, I972a,b).

All niarine phosphorites consist mostly of microcrystalline apatite (carbonate fluorapatite) in the form of laminae, pellets, oolites, nodules and skeletal or shell debris. Uranium, considered syngenetic, may be present in carbonate fluorapatite as a substitute for calcium. Uranium in sea water was probably incorporated during or shortly after precipitation, and it is usually disseminated rather uniformly throughout a given bed or horizon. Primary uranium minerals are rarely present, but secondary uranium minerals (tyuyamunite, autunite, torber-nite) have been identified in a few localities. 

Carbonate sedimentary rocks are dominantly of marine origin. Many limestones are composed of fossilised shell debris in various states of comminution, some fine grained carbonates such as chalk (q.v.) may be entirely composed of sub-microscopic phytoplankton. Algal mats secrete aragonite particles and coral reefs are CeiCO structures which may be preserved, fossilised, intact or degraded to produce other limestones. As discussed above, allochems such as faecal pellets and ooliths may be... 

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