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Medientyp:
E-Artikel
Titel:
Stable Carbon and Oxygen Isotopic Compositions of Recent Charophyte Oosporangia and Water from Malham Tarn, U.K.: Palaeontological Implications
Beteiligte:
Jones, Timothy P.;
Fortier, Steven M.;
Pentecost, Allan;
Collinson, Margaret E.
Erschienen:
Kluwer Academic Publishers, 1996
Erschienen in:Biogeochemistry
Sprache:
Englisch
ISSN:
0168-2563;
1573-515X
Entstehung:
Anmerkungen:
Beschreibung:
<p>Charophyte oosporangia and water samples from a highly calcareous lake were measured for stable carbon and oxygen isotopic composition. The time period over which the oosporangia calcify is short, thus any biochemical relationship between the water and oosporangia's calcite represents only one 'time window' (late Summer in Malham Tarn). This important temporal restraint must also apply to interpretations of all fossil material measured. The δ <sup>18</sup>O<sub>c</sub> of the charophyte oosporangia is deduced to be in equilibrium with the δ <sup>18</sup>O<sub>w</sub> of the water for a given temperature. The δ <sup>13</sup>C<sub>c</sub> of the charophyte oosporangia was approximately 2.5 per mil lower than the δ <sup>13</sup>C<sub>DIC</sub> in the water we measured. With the release of CO<sub>2</sub> with phosphoric acid from the charophyte oosporangia, there was no significant difference in the δ <sup>18</sup>O<sub>c</sub> values obtained, regardless of whether or not the carbonate was separated from the organic center, however δ <sup>13</sup>C<sub>c</sub> values were marginally lower for carbonate plus organic center measurements. Our results indicate that fossil charophyte gyrogonites can be used to elucidate the geochemistry of the ancient water body in which they lived.</p>