The ammonites from the lower shale and isotope age from its upper volcanic rock(define) the age of Sangxiu Formation from Berriasian to Hauterivian of Lower Cretaceous.

• 桑秀组下部的页岩段与江孜甲不拉组的最下部地层相当,上部火山岩的同位素年龄为133 M a。