Study on Origin of Zircon in Mengyin Kimberlite from Shandong Province

The age and the origin of zircons in Mengyin kimberlite from Shandong Province are studied by means of SHRIMP, CL and Raman spectrum, et al. The results show that the ages of ²⁰⁷Pb/²⁰⁶Pb of zircons vary from 2 567±13 to 2 636±42 Ma, which are close to the age of Archaean granitoid (2 457.3±47 Ma)in the research area. The ratio of w(ZrO₂)/w(HfO₂) in the zircons decreases gradually from the core to rim, just like that of the granite-type zircon. Colour zones are obvious under CL. The inclusions in the zircons are feldspar, quartz and apatite. It can be concluded that the zircons come from the crust, which means that the kimberlite magma may be contaminated by the crust.