For radiogenic isotopes that decay slowly enough, or that are stable isotopes, a primordial fraction is always present, since all sufficiently long-lived and stable isotopes do in fact naturally occur primordially.
22.
All forms of isochron dating assume that the source of the rock or rocks contained unknown amounts of both radiogenic and non-radiogenic isotopes of the daughter element, along with some amount of the parent nuclide.
23.
A radiogenic isotope tracer involves an isotope produced by radioactive decay, which is usually in a ratio with a non-radiogenic isotope ( whose abundance in the earth does not vary due to radioactive decay ).
24.
A radiogenic isotope tracer involves an isotope produced by radioactive decay, which is usually in a ratio with a non-radiogenic isotope ( whose abundance in the earth does not vary due to radioactive decay ).
25.
Thus, at the moment of crystallization, the ratio of the concentration of the radiogenic isotope of the daughter element to that of the non-radiogenic isotope is some value independent of the concentration of the parent.
26.
Thus, at the moment of crystallization, the ratio of the concentration of the radiogenic isotope of the daughter element to that of the non-radiogenic isotope is some value independent of the concentration of the parent.
27.
Both short-lived and long-lived radiogenic isotopes indicate that a large-ion lithophile enriched reservoir ( which is the early " crustal " reservoir ) separated from the primitive mantle very early in the history of Mars.
28.
By the early 20th Century radiogenic isotopes had been discovered and British Association for the Advancement of Science came to a rough consensus that the Age of the Earth was a few billion years old, and that radiometric dating was credible.
29.
The relative abundances of different isotopes are then used to describe the chemical fractionation of different isotopes, travel in different reservoirs of non-radiogenic isotopes, and age or origins of solar system objects by the presence of radiogenic daughter isotopes.
30.
To wit, P-\ Delta { P } _ t, D + \ Delta { P } _ t and D _ i respectively correspond to the concentrations of parent, daughter and non-radiogenic isotopes found in the rock at the time of measurement.
