Abstract
The Northern Geological Mapping Federation has completed the work of measuring and mapping the mineral geological map of the Song Ma sheet group at a scale of 1:50,000. Measurement results have delineated an area of about 157 km2 of granitoid rock with light gray to pinkish color, semi-automorphic architecture, and blocky structure. These granitoid rocks were previously classified according to 1:200,000 documents into the Song Ma subalpine system. To clarify the material composition, age of formation and related mineralogy of the complex, the project first took samples for silicate analysis, ICP-MS and 02 samples for U-Pb zircon isotopic age analysis. Zircon was selected from granite, biotite horblende granite in Co Hay, Nam Soi, Muong Cai commune, Song Ma district, age determined by LA-ICP-MS, U-Pb methods for age 239.7±3, 9 million years and 243±1.9 million years (Ma), this age is considered their crystallization age. The granitoid formations cut through the eruptive rocks of the Muong Hinh formation, so it can be confirmed that the crystallization age of the sub-volcanic Muong Hinh eruptive rocks of the Sam Nua zone must be older than 243 million years (Ma). This research work is important in determining the age of formation for intrusive and eruptive magmatic rocks in the Sam Nua zone in the Song Ma area, one of the studies that has had many different views in recent times.