However, the paper is not terribly helpful to the young-Earth cause. Zheng discusses four ways in which an incorrect isochron could result:
Protracted fractional crystallization Requires a slow cooling period on order of ten million years, which is not possible on a young Earth. Also, the effect is very slight: in the only example which Zheng produces (first entry in Table II on p. 14), the "incorrect" age (437 ± 10 Ma) is not very different from the actual age (415 ± 10 Ma).
Inherited (for example, by partial melting) Discussed previously; requires special circumstances and almost always induces a fair amount of scatter in the isochron plot. Requires ancient source material (the "inherited" age matches the age of the source), which is not available on a young Earth.
Mixing isochron Discussed previously; in most cases detected by the mixing plot test.
Apparent isochron by metamorphism Discussed previously; requires special circumstances and results in an age in between original time of crystallization and the metamorphic event that partially reset the isochron. Requires ancient source material, which is not available on a young Earth.
While each of these processes can be invoked to explain a few confusing or conflicting dating results, none could reasonably be expected to account for all (or even most) isochron dating results which are incompatible with a young Earth.
Thanks, I wasn't in the mood to hike to the library and look this up today.
It wasn't meant to account for the YEC.
Merely to show how poorly isochrons are at deriving alleged dates.