text: There are some disputes about using I-Xe dating to estimate the Xe closure time. First, in the early solar system, planetesimals collided and grew into larger bodies that accreted to form the Earth. But there could be a 10 to 10 years time gap in Xe closure time between the Earths inner and outer regions. Some research support 4.45 Ga probably represents the time when the last giant impactor (Martian-size) hit Earth, but some regard it as the time of core-mantle differentiation. The second problem is that the total inventory of Xe on Earth may be larger than that of the atmosphere since the lower mantle hadnt been entirely mixed, which may underestimate Xe in the calculation. Last but not least, if Xe gas not been lost from the atmosphere during a long interval of early Earth's history, the chronology based on I-Xe would need revising since Xe and Xe could be greatly altered.