tailieunhanh - General characteristics of rare earth and radioactive elements in Dong Pao deposit, Lai Chau, Vietnam

The water samples were taken from the streams, natural tap and thermal water intakes localized in the studied deposit and surrounding region. The 238U, 234U, 228Ra, 226Ra concentrations in the water samples were prepared by the adequate radiochemical procedures and measured using an alpha spectrometer coupled with silicon semiconductor detector and a/b liquid scintillation counter. In the stream water, the concentrations of both 226Ra and 228Ra vary from 100 to above 300 mBq/L, while in the natural tap and thermal waters they amount to tens mBq/L. | Vietnam Journal of Earth Sciences, 39(1), 14-26, DOI: Vietnam Academy of Science and Technology Vietnam Journal of Earth Sciences (VAST) General characteristics of rare earth and radioactive elements in Dong Pao deposit, Lai Chau, Vietnam Nguyen Dinh Chau1*, Pieczonka Jadwiga1, Piestrzyński Adam1, Duong Van Hao3, Le Khanh Phon3, Jodłowski Paweł2 1 Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and Technology (AGH UST), al. Mickiewicza 30, 30-059 Kraków, Poland 2 Faculty of Physics and Applied Computer Science, AGH University of Science and Technology (AGH UST), al. Mickiewicza 30, 30-059 Kraków, Poland 3 Faculty of Oil and Gas, Hanoi University of Mining and Geology (HUMG) Received 08 December 2016. Accepted 2 February 2017 ABSTRACT One of the important rare earth deposits is the Dong Pao localized in Lai Chau province, West-North of Vietnam. Generally, the deposit is composed of two parts, the lower and the upper. The lower part is composed of dolomite, limestone and intrusive rocks, while the upper part of the profile is represented by a weathered zone containing soil and fragments of mixed barite-fluorite ores. The concentrations of natural radionuclides, chemical compositions of ores, including rare earth elements (REE) in solid samples, were determined by gamma spectrometer equipped with a HPGe detector, laser ablation inductively coupled plasma mass spectrometry (LA ICPMS) and activation method, respectively. In the samples taken from the ore bodies within the weathered zone the REE concentration is about 10 wt.% and both 238U and 232Th amount to wt.%, while in the samples from the hard part of ore the REE and 238U as well as 232Th contents amount only to wt.% and wt.%, respectively. So the enrichment of the REE and natural radioactive elements in the deposit is a consequence of the weathering processes. The water samples were taken from