Geology and Radionuclide Ratio Mapping For Radioactive Mineral Exploration in Mamuju, West Sulawesi

Mamuju is an exploration area for uranium (U) and thorium (Th) which has been conducted since 2012. The anomaly of radioactivity are in wide area with significant of uranium and thorium grade. Uranium and thorium mineralization occurences in Mamuju area associated with the distribution of volcanic rocks, which are grouped into volcanic rocks Adang. This study aims to identify the distribution of radioactive minerals source rocks and deposits of in Mamuju Region. The study was conducted by geological, mapping of radionuclide and rocks chemical analysis. Geological mapping indicates that the volcanic rocks Adang consists of seven volcanic complex which is Tapalang, Ampalas, Adang, Malunda, Karampuang, Sumare and Labuan Rano. Radionuclides mapping using gamma survey meter (RS-125 models) in Mamuju shows the variation of the dose rate (nSv/h), the levels of radionuclides potassium (%K), uranium (ppm eU) and thorium (ppm eTh) at each measurement point were measured continuosly. Radionuclide data processing using radionuclide ration Th/K, U/K may provide an overview of different distribution of volcanic rocks between older volcanic complex (Tapalang, Ampalas and Malunda) with younger (Adang, Karampuang, Sumare and Labuan Rano). Radioactive mineralization are controlled by several factors, which are the distribution of lithology ultrapotasik/shosonitik especialy complex Adang volcanic rocks as radioactive mineral source rocks and favorable volcanic rocks the Tapalang, Ampalas and Malunda complex, hydrothermal process which fills the structure northeast-southeast, nort-south and east-west trending, and also supergene enrichment process which includes the weathering, leaching and deposition process of radioactive elements.