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Estimating P-T Conditions of Metamorphic Rocks Exposed in Mawlu Area, Indaw Township, Sagaing Region with Isochemical Phase Diagram Sections
- The study area lies in Indaw Township, northeastern part of Sagaing Region. It is situated between Latitude 24° 20ʹ to 24° 35ʹ N and Longitude 96° 10ʹ to 96° 20ʹ E. The present study area is chiefly made up of metamorphic rocks and minor sedimentary rocks. They occupy the entire bulk of the Katha-Gangaw Range. On the basis of petrographic analysis, nine representative mineral assemblages are distinctive in various types of schists occurred in the study area (eight in metapilite and one in metabasite). According to mineral assemblages, the metamorphic rocks of the research area indicate lower greenschist facies to upper amphibolites facies. Isochemical pressure-temperature phase-diagram sections portray the theoretical equilibrium distribution of mineral assemblages and mineral compositions for a given bulk-composition. Isochemical sections for garnet-staurolite-sillimanite-muscovite-quartz, garnet-kyanite (sillimanite)- muscovite-quartz of pelitic rocks from sillimanite zone and garnet-actinolitetschermakite- chlorite-biotite-quartz-epidote of metabasite rocks from garnet zone at Mawlu area, were calculated in the system MnO-Na2O-CaO-K2OFe2O3- MgO-Al2O3-SiO2-H2O-TiO2 using bulk compositions derived by X-ray fluorescence (XRF) analysis. Procedures of calculation methods to produce P-T pseudosection diagrams are used to Perple-X computer program. These sections were constructed in the interval 2-12 kilobars, 400- 800°C to cover the P-T conditions. The phase-diagram sections for the XRF derived composition indicates that the garnet zone and sillimanite zone metamorphic rocks occurred at approximately 3 kilobars to12 kilobars at 470-735°C.
Aung Khin Soe
Than Than Nu
- Monywa University Research Journal