Petrochemistry of granitic rocks in Tha Pai area, Mae Hi sub-district, Pai district, Mae Hong Son province, Northern Thailand

Granitic rocks in the Ban Tha Pai area, Mae Hi sub-district, Pai district, Mae Hong Son province, are located in the western line of the Central Granitic Belt in northern Thailand. These granitic rocks are in N-S orientation and have a Triassic age. Petrographic investigation of the granitic rocks indicates that they are monzogranite with medium to coarse-grained porphyritic texture. Mineral compositions of them mainly consist of quartz, K-feldspar, and plagioclase, with minor biotite and small amounts of muscovite, apatite, zircon, titanite, and opaque minerals. Geochemical investigation of the granitic rocks indicates that they are in sub alkaline series and almost totally of high-K calc-alkaline affinity. Furthermore, the granitic rock samples were S-type granite and peraluminous rock. According to tectonic discrimination diagrams, the granitic rocks might have formed in an orogenic environment