Additionally, a Th/U evolution (or: Th/U-time) diagram can be plotted using U-Pb zircon age data and Th/U ratios from volcanic rocks and ashes reported in the literature  for specific Devonian samples from the Appalachian Basin.
Since the Re-Os age obtained for SDO-1 can also be connected to its Th/U ratio, it turns out, that Th/U ratios might be helpful age indicators, as demonstrated for the Devonian using the U-Pb and Re-Os datasets.
Hence, SDO-1 can be assigned to the Givetian stage (varcus-zone) of the Middle Devonian, close to the Eifelian/Givetian boundary (using the time-scale of  or ).
If an age is calculated from an isochron diagram for the 12 aliquants including the nuclear geochronometer, a permil precision can be achieved, an interesting feature with respect to any effort towards calibrating the Geologic Timescale.
The peridotites were also analysed for the 187Os/188Os compositions at the single grain base metal sulphide (BMS) and platinum-group mineral (PGM) scale.
These analyses indicate that the Kaapvaal peridotites have experienced high degrees of melt depletion followed by variable and significant enrichment in the incompatible trace elements and HSE.
In contrast, molybdenite from quartzite adjacent to the pegmatite gave a Re-Os age of 353 ± 2.5 Ma.
For geological purposes, this is taken as one year. Kontak Nova Scotia Department of Natural Resources, P. Heaman Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB T6G 2E3Douglas A. Creaser Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB T6G 2E3Larry M. This decay process leads to a more balanced nucleus and when the number of protons and neutrons balance, the atom becomes stable.This radioactivity can be used for dating, since a radioactive 'parent' element decays into a stable 'daughter' element at a constant rate.Recently, 187Re - 187Os nuclear geochronometry, a new dating method combining ideas of nuclear astrophysics with geochronology, has successfully been used to calculate two-point-isochron (TPI) ages for Devonian black gas shales using the isotopic signature of an r-process geochronometer as one data point in a TPI diagram .