Geological features and SHRIMP U-Pb zircon age of the Yanwan-Yinggezui ophiolitic mélange in the Taibai area, West Qinling, China

The Yanwan-Yinggezui ophiolitic mélange in the West Qinling orogenic belt is an important component part of the Shangdan ophiolitic mélange. It is composed of tectonic blocks of metabasic volcanic rocks (basalt), serpentinite, metagabbro, cherts and meta-flysch (mica-quartz schist), of which basalt blocks have the geochemical features of N-MORB and andesite is subduction-related island-arc rocks. The zircon SHRIMP U-Pb age of basalt is 483±13 Ma, which agrees with the age of the Guanzizhen and Danfeng ophiolitic mélanges. The study of the composition and age of the Yanwan-Yinggezui ophiolitic mélange can provide important geological evidences for a further study of the evolution of the Shangdan ophiolitic mélange and accretionary orogeny of the Qinling orogenic belt.