Abstract

• The research area lies between latitude 20° 34 00 to 20° 45 00 north and longitude 97° 15 00 to 97° 22 30 east, which is situated about 21 km, southeast of Hopong township, Southern Shan State. The intrusive igneous rocks are granites and muscovite-biotite granites. The granitic rocks show chemical composition (weight percent) of SiO2 (70.35-74.20), Al2O3 (13.69-16.59), TiO2 (0.21-0.39), Na2O+K2O (7.85-9.31), Fe2O3+MgO (1.72-3.74), MnO (0.03-0.05), CaO (0.560.80) and P2O5 (0.20-0.30). Petrochemically, P (K-(Na+Ca)) - Q (Si/3-(K+Na+2Ca/3)), R1-R2, normative (Ab - Or - An) and TAS diagrams indicate that the granitic rocks from the research area belong to the granite field. In the molar Na2O-Al2O3-K2O and B-A plot diagrams show that granites and muscovite-biotite granites are predominantly peraluminous. AFM diagram indicates that the granitic rocks belong to the calc alkaline series. From the result of K2O Vs Na2O diagram, granites and muscovite-biotite granites of the research area involve S-type. Normative data plot of Quartz-Albite-Orthoclase diagram shows that the granitic rocks lie within 2kb and 10 kb during crystallization. According to ternary plot of Quartz-Anorthite Orthoclase diagram exhibits that the majority of all granitic rock samples were formed between 0.5kb and 5kb. It can be interpreted that the granitic rocks were consolidated under the low pressure condition. Due to the relationship between differentiation index and temperature, the liquidus temperatures are 720˚C for granites and muscovite-biotite granites. From the schematic depth-temperature diagram, it is indicated that the granitic rocks from the research area crystallized at the depth of 26 km. The granitoid rocks of the research area are Orogenic granitoids. Therefore, the granitic rocks were formed on the continent relation to the subduction of an oceanic plate beneath the continent. R1-R2 binary (millication) diagram indicates the granitic rocks of the research area correspond to syn-collision zone.