Calibration of the [delta]18O paleothermometer
for dolomite precipitated in microbial cultures and natural environments: Geology.
Calibration of the carbonate 'clumped isotope' paleothermometer
This temperature dependency was first described in an empirical equation (for use as a paleothermometer
of minerals) by McCrae (1950).
"If the correlation holds, we would have a thermometer that goes back in time, a paleothermometer
of how hot or cold water temperatures were when the nacre formed," says Gilbert.
An increasingly versatile proxy determined from foraminifera tests is the Mg/Ca ratio, which is an important paleothermometer
. Other promising proxies are: the Sr/Ca ratio in coccoliths, which correlates with rates of organic carbon fixation and calcifcation; [delta][sup.30]Si and [delta][sup.15]N values in diatoms, which denote nutrient utilization; and Sr/Ca and U/Ca ratios in corals, which relate to sea-surface temperatures.
Using a new type of paleothermometer
the team developed, the researchers have determined the average temperatures during the Late Ordovician-the first time they have been able to tide over the issue.
The application of the organic paleothermometer
[TEX.sub.86] (based on the distribution of species of membrane lipids of the marine picoplankton Crenarchaeota; Schouten et al.
The new "clumped-isotope" paleothermometer
method used in the study analyzes two rare heavy isotopes, carbon-13 and oxygen-18, found in tooth enamel, bones and eggshells.
Now, scientists might be able to use phytoliths from long-decomposed plants unearthed from soil as paleothermometers
, Zhenzhen Huang of the University of Western Ontario in London, Canada, reported May 26.