Chemical Th-U-total Pb isochron age of zircon from the Mereb Granite in northern Ethiopia

The chemical Th-U-total Pb isochron age was detemined for zircon grains from the post-tectonic Mereb Granite in northern Ethiopia. Twenty-seven ana-lyses from five zircon grains yield a well defined isochron of 545±24 Ma. One of the analyzed grains is chronologically zoned with a core having age range of 732-828 Ma. The core is interpreted as a xenocryst. The 545±24 CHIME zircon age, slightly younger than the previously reported Rb-Sr whole-rock isochron age of 633±62 Ma, dates emplacement of the Mereb Granite, and agrees well with the 541+10/-16 Ma U-Pb zircon age for the post-tectonic Mao granite in western Ethiopia.