SHRIMP dating of the aoyougou ophiolite in the West sector of the North Qilian Mountains and its geological significance

The SHRIMP U-Pb zircon data of a diabase from the Aoyougou ophiolite in the west sector of north Qilian Mountains are reported in the paper. It shows that the Aoyougou ophiolite was formed in the early middle Proterozoic (about 1777Ma), and proves that it is the earliest ophiolite that has been reported in China. In addition, the dating implies that two geological events occurred about 1466 Ma, and 507 Ma, respectively. The former one probably represents the least closure age of the ocean basin of the early middle Proterozoic whereas the latter one represents the Caledonian regional metamorphism. Moreover, Late Archean crystallized basement (about 2561 Ma) may present in the area although it did not outcrop.link_to_subscribed_fulltex