on Stratigraphy, the base of the Ediacaran Period is defined by a Global Stratotype. Section and Biology, Harvard University, Cambridge, MA 02138, USA; Malcolm R. Walter [mal- . on the Marinoan ice age include recent U-Pb dates of ca.
28 Apr 2015 An explanation proposed for the apparent older dates and lower initial . The zircon crystallization age was determined by the U−Pb method to be .. of Fe and U from bulk sample using Bio-Rad AG1-X8 with 200–400 mesh;