Abstract:

The Mazha tectonic melange was discovered and determined during the 1∶250,000-scale regional geological mapping in the Mazha region. The blocks are composed of the arc complex, arc-related sedimentary rocks and exotic blocks and can be classified as 15 blocks that contact with each other by faults. The matrix which lies around the blocks is composed of the tectonic schists and dynamometamorphic rocks. Many important information about the subduction processing of the old oceanic crust revealed through the detailed study of the Mazha tectonic melange. Zircon SHRIMP dating of the hornblende-quartz-diorite from the Mazha melange was carried out in this study. The results are (338±10）Ma in age, which shows that the hornblendequartz-diorite is formed in Early Carboniferous. The discovery and study of the Mazha tectonic melange have not only enriched the contents of the MazhaKangxiwa suture zone , but also advanced the evolvement age of the suture zone to Early Carboniferous, and offered basic data for the study of West Kunlun orogenic belt.

Key words: Mazha of West Kunlun mountains, tectonic melange, zircon SHRIMP U-Pb dating, Early Carboniferous