Chromium isotopic ratios are homogeneous within the earth, and therefore these isotopic anomalies exclude a volcanic origin, which has also been proposed as a cause for the iridium enrichment.
42.
Typically, varve refers to lake or glacial sediment ), as temperature induced changes in the isotopic ratios for oxygen isotopes in sediments, and in the relative abundance of fossils.
43.
Meteoritic standard was chosen because of the constancy of the sulfur isotopic ratio in meteorites, whereas the sulfur isotopic composition in Earth materials varies due to the bacterial activity.
44.
A 2008 analysis of 12 C / 13 C isotopic ratios of organic compounds found in the Murchison meteorite indicates a non-terrestrial origin for these molecules rather than terrestrial contamination.
45.
Hafnium / tungsten ( Hf / W ) isotopic ratios, when compared with a chondritic reference frame, show a marked enrichment in the silicate earth indicating depletion in Earth's core.
46.
His main interest was in the study of atmospheric / ionospheric composition and isotopic ratios for which he has developed instrument packages that have flown on many rockets and satellites.
47.
These differences in isotopic ratio are then biologically'set'in our hair as it grows and it has therefore become possible to identify recent geographic histories by the analysis of hair strands.
48.
The third would measure carbon and hydrogen isotopic ratios, together with the abundance of methane relative to other alkanes, to assess whether the values fall in the range for biological processes.
49.
Based on 12 C / 13 C isotopic ratios of organic compounds found in the Murchison meteorite, it is believed that uracil, xanthine and related molecules can also be formed extraterrestrially.
50.
The original concentration of cosmogenic isotope in the sample is then calculated using the measured isotopic ratio, the mass of the sample, and the mass of carrier added to the sample.
