SHRIMP U-Pb Ages, Geochemical Characteristics and Geological Implications of the Monzonitic Granite at South Liushitage, West Kunlun

The monzonite granite developed in the accretionary wedge in South Kunlun (South Liushitage) and intruded in the deep metamorphic rocks of Paleoproterozoic Shuangyanshan group, unconformably covered by the Triassic Atamupa formation. The rock is mainly light meat-red finegrained monzonitic granite, localized gradient to granodiorite or syenite granite, with also a small amount of gabbro occurred later in it. SHRIMP Zircon U-Pb dating is relatively concentrated and located near the concordia curve. With the weighted average age of 455.9±7.4 Ma, the monzonite granite should have formed in late Early Ordovician. The petrological, geochemical characteristics displayed as a sequence of calc-alkaline. The high potassium content and the presence of ancient zircons show that the rock is probably a result in subduction-collision tectonic environment, indirectly certificating that the limited ocean basin in South Kunlun has closed at the Late Ordovician. This finding has a great geological significance by providing new geological basis for the tectonic evolution of the Kunlun orogenic belt.