Study of natural thermoluminescence of quartzite in a gold and uranium mineralized zone (Canavieiras, Jacobina, Brazil)
Creators
- 1. Bahia Univ., Salvador (Brazil). Inst. de Geociencias
- 2. POND-UNESCO
Description
The quartzite of the Canavieiras gold mine (Jacobina, Bahia, Brazil) exhibits a high temperature peak (280 +- 2)0C in its natural thermoluminescence glow curve. It was experimentally determined that the amount of light in this peak could be reproduced to within 5% for grain sizes between 80 and 100 mesh (0.149 and 0.177 mm). A positive correlation was found between the amount of this thermoluminescence and the uranium content with saturation beginning to be detected at the maximum (700 ppm) amount of uranium found. Assuming that the thermoluminescence peak used is at a temperature high enough to permit accumulation and stability at room temperatures, the thermoluminescence found could have accumulated in (12.1 +- 0.3) x 106 years. This may date a complete liberation of trapped electrons in conjunction with a well documented initiation of weathering. (author)
Abstract (Portuguese)
O quartzito da mina de ouro de Canavieiras (Jacobina, Bahia, Brasil) exibe um pico de alta temperatura (280 +- 2)0C na sua curva de brilho de termoluminescencia natural. Determinou-se experimentalmente que a quantidade de luz neste pico poderia ser reproduzida dentro de 5%, para tamanhos de grao entre 80 e 100 mesh (0,149 e 0,177 mm). Encontrou-se uma correlacao positiva entre a quantidade desta termoluminescencia e o teor de uranio, com saturacao comecando a ser detetada, para a quantidade maxima encontrada de uranio (700 ppm). Admitindo que o pico de termoluminescencia usado esteja a uma temperatura suficientemente alta para permitir acumulacao e estabilidade a temperaturas ambientes, a termoluminescencia encontrada poderia ter-se acumulado em (12,1 +- 0,3)x106 anos. Isto pode indicar a data em que ocorreu uma liberacao completa de eletrons capturados em armadilhas, ao mesmo tempo que uma iniciacao bem documentada de intemperismo. (I.C.R.)Additional details
Additional titles
- Original title (Portuguese)
- Estudo da termoluminescencia natural do quartzito em uma zona mineralizada em ouro e uranio (Canavieiras, Jacobina, Bahia)
Publishing Information
- Journal Title
- Rev. Bras. Geocienc.
- Journal Volume
- 6
- Journal Issue
- 4
- Series
- Rev. Bras. Geocienc.
- Journal Page Range
- 264-277
- ISSN
- 0375-7536
INIS
- Country of Publication
- Brazil
- Country of Input or Organization
- Brazil
- INIS RN
- 11521603
- Subject category
- S58: GEOSCIENCES;
- Descriptors DEI
- AGE ESTIMATION; GAMMA SPECTROSCOPY; GOLD; GRAIN SIZE; HIGH TEMPERATURE; MINERALIZATION; POTASSIUM 40; QUANTITY RATIO; QUARTZITES; THERMOLUMINESCENCE; THORIUM 232; URANIUM; URANIUM 238
- Descriptors DEC
- ACTINIDE NUCLEI; ACTINIDES; ALPHA DECAY RADIOISOTOPES; BETA DECAY RADIOISOTOPES; BETA-MINUS DECAY RADIOISOTOPES; BETA-PLUS DECAY RADIOISOTOPES; CRYSTAL STRUCTURE; ELECTRON CAPTURE RADIOISOTOPES; ELEMENTS; EVEN-EVEN NUCLEI; HEAVY NUCLEI; ISOTOPES; LIGHT NUCLEI; LUMINESCENCE; METALS; METAMORPHIC ROCKS; MICROSTRUCTURE; NUCLEI; ODD-ODD NUCLEI; POTASSIUM ISOTOPES; RADIOISOTOPES; ROCKS; SIZE; SPECTROSCOPY; THORIUM ISOTOPES; TRANSITION ELEMENTS; URANIUM ISOTOPES; YEARS LIVING RADIOISOTOPES