Abstract

• Taung-Pi-La Area is situated about 3.84 miles (6.22 kilometers) west of Kalemyo, Sagaing Region. The principal rock types of the Taung-Pi-La Area include harzburgite, dunite and serpentinites which are formed during Late Jurassic to Early Cretaceous. Exposures of pyroxenite were observed in the research area. Seven chromitites occurred in the Taung-Pi-La ultramafic rocks. Chromitite are massive, nodular and disseminate types displaying pull-apart, cataclastic, net and clot textures. Among the chromite grains, the interstitital silicate of olivine, orthopyroxene and serpentine are found. X-ray diffraction (XRD) of chromitites of the Taung-Pi-La Area shows magnesiochromite (MgCr2O4) type. Chromitite composition is characterized by Cr2O3 ranging from 27.10 to 59.43 wt.%, Al2O3 from 7.36 to 26.60 wt.%, MgO 8.27 to 26.80 wt.%, and FeO ranges from 4.37 to 14.66 wt.%. The maximum Fe2O3 content is 2.45 wt% and TiO2 is always below 0.18 wt%, as typical for podiform chromitites and ophiolitic chromitites. The high-Cr chromitites are typically hosted in highly depleted harzburgites. In the TiO2 vs. Cr2O3, Mg#[Mg/(Mg+Fe2+)] versus Cr#[Cr/(Cr+Al)] and TiO2 vs. Fe2+/Mg diagrams, most of the chromitites belongs to the podiform chromitites. The trivalent ion plot (Cr-Al-Fe3+) and Al2O3 vs Cr2O3 of chromitite compositions show that chromitites are derived from mantle source. According to the TiO2and Al2O3 diagram, chromitites of the Taung-Pi-La Area are formed in the supra-subduction zone (SSZ).