National Museum of Natural Science

Metamorphic and sedimentary rocks contain the oldest minerals on the earth. In the mountains of western Australia is hidden detrital zircon within conglomerate formed 3.06 billion years ago. This zircon was analyzed using SHRIMP (Sensitive High Resolution Ion MicroProbe) and the results showed that zircon 207Pb/206Pb is 44.04 million years old. At the same time, it has a high oxygen isotope ratio (δ18O=7.4) and quartz inclusions, indicating that zircon crystallization originated across differentiated magma and that continental crust granite and oceans had formed.

Metamorphic and sedimentary rocks