LA-ICP-MS Zircon U-Pb Age of Gabbro and Basalt in the Baimuxia Area of North Qilian and Its Geological Significance

The gabbro and basaltare hosted in the Baimuxia Ophiolitemelange belt of North Qilian with the form of various blocks.After carrying out the detailed field investigation and studies of petrology and lithology ongabbro and basalt in the Baimuxia area, the LA-ICP-MS zircon U-Pb dating of gabbro and basalt samples has yielded the accurate ages of (675±31)Ma and (764.1±3.3)Ma, which can represent theirdiagenetic ages.The results reveal that one important magmatic activity may be existed in the North Qilian area during Middle Neoproterozoic, which could be related to the global cracking of Rodinia supercontinent.The dating of LA-ICP MS zircon U-Pb provide accurate geochronological constraints for studying the formation and evolution of the North Qilian tectonic zone.