Altun Mountains were not boundary mountains between Tarim and Qaidam Basins after Indo-China movement or even earlier.It has been proved that the two basins werelinked up and connected to each other before the Quaternary.They share the same condi-tions of salt and sylvite generation.It was not until Post-Miocene that the mountains hadits embryonic shape of subaqueous uplifts;it further rose as island-like uplifts at the end of Neogene(2.6—2.10Ma.B.P.)

and then became the boundary mountains to block the Tarim and the Qaidam Basins in Late Pleistocene(0.25Ma.B.P.).