Phosphate deposit at Eppawala is one of the major mineral resources in Sri Lanka. Although the exploitation has been carried out over several decades, and many geochemical and mineralogical studies have been done, no detailed geophysical investigation had been conducted until this project. We use the fact that magnetite is always associated with the phosphate deposit, due to its igneous origin. Due to the presence of magnetite, phosphate body has a unique magnetic signature, which is distinctively different from the surrounding country rocks. In this research, a magnetic survey is conducted to obtain the magnetic signals from rocks and establish the characteristic magnetic signatures of the country rock, parent rock and secondary phosphate rock.
Total magnetic intensity of the area was obtained using a proton precision magnetometer. After filtering the noises, data were processed to produce the magnetic anomaly map of the area. Phosphate deposit can be demarcated using the sharp magnetic anomaly.
Prof. Deepal Subasinghe