SHRIMP Zircon Age of the Aermantai Ophiolite in the North Xinjiang Area,China and Its Tectonic Implications

Abstract

We present a new analysis and interpretation of the geological and tectonic history of the Chinese East Junggar orogenic belt together with new, structural observations, geochronological and geochemical data. The northerly-distributed Armantai ophiolite shows mainly E-MORB and island arc-basalt geochemistry, and a plagiogranite from the ophiolite yields a new SHRIMP zircon age of 503±7 Ma. These juxtaposed tectonic units indicate multiple subduction-accretion systems amalgamated by subsequent oblique convergence, including remnants of island arc, subduction complexes, seamount and ophiolites, forming an enlarged Cordilleran-type margin by Mid-Carboniferous time. This scenario has wide implications for the architecture and crustal growth of Central Asia.