Petrochemical Characteristics of Granitoid Rocks in the Southern part of Maungmagan Area, Launglon Township, Tanintharyi Region

The research area is situated in Launglon Township. Dewei District, Tanintharyi Region, covering about 64 square kilometers. It lies in the Shan Tanintharyi Block, representing the Southern part of tin-bearing granitoid belt of Southeast Asia. The area is made up of NNWSSE trending granitoid reeks; including porphyritic biotite granite, biotite granite. Porphyritic biotite microgranite, hornblende biotite granodiorite and aplite. Structurally, two minor fault systems are recognized from the satellite image and field evidences. These are NW-SE and Nearly N-S trending longitudinal fault and NE-SW trending cross fault Joint pattern shows that there were NE-SW compressional and NW- SE extensional force in the area Nearly N-S trending aplite dyke is intruded into biotite granite and then aplite dyke contains molybdenite which is in important source of economic interest. Geochemically, the granitod rocks fall in the granite and monzonite field. They are S1baIkaiinc affinity and belong to the calc-alkaline series. Moreover, porphyritic biotite granite biotite granite and porphyritic biotite microgranite fall in the high potassium calc-alkaline series hornblende biotite grandiorite falls in the calc-alkaline series. metaluminous to slightly peraluminous in nature, end I type in origin The decreasing of Al2O3, CaO, P2O5, MgO, Fe2O3, MnO and TiO2 with increasing SiO2 suggests that the granitoid rocks were formed due to fractional crystallization during magmatic evolution According to field evidences and petrographic characteristics, the granitoid rocks in the study area are considered to be magmatic a igin. Liquidus temperature can be estimated for porphyritic biotite granite and porphyritic biotite microgranite as 705°C, biotite granite as 710ºC and that of hornblende biotite granodiorite is 695°C. Generally, it may be suggested that the granitoid rocks in the study area may crystallize at depth between 20 Km and 22km and the depth of emplacement is estimated at mesozone. Radiometic dating by U Pb Zircon age method indicates that the age of porphyritic biotite granite is 61±2 Ma, biotite granite is 60.58±0.75 Ma end that of porphyritic biotite microgranite is 59.04±0.53 Ma. Therefore, the granitoid rocks in the study area were successively emplaced during Paleocene. Granites from the study area can be used as decorative stones and dimensional stones. Granites can also be extracted for construction and road materials. The economic interest of the study area is the occurrence of ore mineral especially molybdenite and the economic minerals of rare earth elements