Oxygen core composition

Figure 10. Lithium isotopic compositions of minerals from the Tin Mountain pegmatite. Black Hills, South Dakota (Tomascak et al. 1999c). Differences in the equilihrium quartz-feldspar oxygen isotopic compositions between the wall zone and intermediate zones suggested temperatures of 600 to 550°C (Walker et al. 1986). Despite poor precision of these data, they showed a consistent increase in the A Li, ,. between the early-crystallizing wall zone and the later-crystallizing core.

Among the few examples of hybrid materials using the metal-oxygen core for their construction is the composite obtained from BuSn(OPri)J. The hydrolysis-polycondensation reactions are quite fast for the derivatives of tin (as the increase in the coordination number takes place), but the Sn-C bond is quite stable against the attacks of nucleophilic reagents like water. It makes possible the addition of the organic molecules to the oxopolymers — the tin-... 

The discovery of the anomalous oxygen isotopic compositions of atmospheric sulfate provides a new means for identifying sulfate of atmospheric origin. Rainwater and aerosols from southern California were found to have A O values in the range of 0%o to -K.5%o (Lee et al., 2001). The average A O of snow sulfate in the Rocky Mountains (Colorado, USA) was - -1.3%o. Sulfate in ice cores, massive sulfate deposits, and Dry Valley soils from various locations also have MIF (Bao et al., 2000 Lee et al., 2001). There appears to be seasonality in the A O of sulfate in precipitation, with higher values in the winter and lower values in the summer, probably due to seasonal changes in climatic elfects that favor aqueous phase S(IV) oxidation in winter relative to summer (Lee and Thiemens, 2001). 

Savarino J., Alexander B., Michalski G. M., and Thiemens M. H. (2002) Investigation of the oxygen isotopic composition of nitrate trapped in the Site A Greenland ice core. 

Blake R. E. and Turekian K. K. (2000) Phosphate oxygen isotope composition of fish debris as a chronostratigraphic tool results from LL/14-GPC3 a Pacific red clay core. EOS 81(suppl. 2), F707. 

Figure 4 Mg/Ca of different planktonic foraminifera from a Bermuda sediment trap time series, plotted versus calcification temperatures calculated from the oxygen isotopic composition of the shells (Anand et aL, 2003) (reproduced by permission of American Geophysical Union from Paleoceanography 2003, 18, 1050). The aggregate fit to all the data in the plot is Mg/Ca = 0.38 exp(0.09T), very similar to relationships derived from culturing and core-top studies.

Type II calcite occurs as microcrystalline (1-60 pm) aggregates that exhibit complex, thin CL zonation (Fig. 7A,B). It is more common in the oil zone, yet its occurrence is mainly related to the unevenly distributed bioclasts and bioclastic moulds in the cored interval. Below the water-oil interface calcite 11 is scarce and occurs always in association with type 111 (Fig. 8). Type II calcite has oxygen isotope compositions ranging between -5%o and -l%o. 

In order to test this hypothesis Faure et al. (1992) determined 8 0 values of ice collected along surveyed lines that extended up to 3 km from the baseline in the Reckling Moraine into the adjacent ice fields both north and south of the moraine. In addition, eight vertical ice cores were angered to a depth of about 1 m each, within a 2-km distance along one of the surveyed lines that crossed the moraine. The oxygen isotope composition of the ice in these cores was analyzed at 1-cm intervals in the Quaternary Isotope Laboratory at the University of Washington in Seattle. 

Figure 7. (a) Vostok ice core CO2 record reported as ppmv (part per million by volumbe) (9). (b) Ocean sediment core (G. ruber, a species of foraminifera) oxygen isotope record reported as the deviation in parts per thousand from the marine carbonate standard V-PDB (both sea-surface temperature and changes in the bulk seawater oxygen isotope composition affect this record) (49), and boron isotope based pH values reported relative to the seawater pH scale (large squares) (50). (c). Continental ice volume signal from seawater reported... 

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