Determination of the REE content, geological age, and absorbed alpha dose of allanite mineral from Palawan, Philippines

Dingle, Cheri Anne M.; Jecong, J.F.M.; Hila, Frederick C.; Ramo, Ma. Elina Salvacion V.; Guillermo, Neil Raymund D.; Vasquez, Magdaleno R.; Samson, Vallerie Ann

doi:10.1002/xrs.3029

Cited by 2 publications

(5 citation statements)

References 23 publications

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“…This could potentially explain the occurrence of U in the farmlands and the low correlation coefficient between U and Th (r 0.67). Previous estimates of U and Th concentrations in the allanite using 241 Am-excited X-ray fluorescence shows the occurrence of Th as a major element at 11,873 ± 0.086 ppm and U as a minor element at 150 ± 0.0056 ppm (Dingle et al, 2019).…”

Section: Radiometric Anomalies and Source Identificationmentioning

confidence: 95%

“…Allanite is a common accessory mineral in igneous rocks that contains U and Th (Hermann, 2002). Determination of U and Th contents of the allanite in Erawan using 241 Am-excited X-ray fluorescence indicated concentrations of 150 ± 0.0056 ppm and 11,873 ± 0.086 ppm, respectively (Dingle et al, 2019). Despite numerous studies conducted in Erawan and neighboring areas, it is still unproven whether the allanite originated from the granitic bodies.…”

Section: Introductionmentioning

confidence: 99%

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<em>In situ</em> Ground Radiometric Survey and Risk Assessments of Allanite-Bearing Beach Sands in Erawan, Palawan

Diwa¹,

Vargas²,

Tabora³

et al. 2021

Preprint

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Past exploration for U deposit in the Philippines discovered the mineralization of radioactive allanite in Palawan. The allanite occurs as sand component in the heavily populated beach of Erawan, San Vicente, Palawan. This work assessed the risks associated with the radionuclides in Erawan beach by in situ ground radiometric survey of K, U, and Th in 694 sampling points. Principal component analysis (PCA) and Pearson correlation coefficient were used to determine the similarity between the radionuclides and to identify other probable anthropogenic sources of radionuclides. Our results show that the mean activity concentrations of K (597.8 Bq kg-1) and Th (93.15 Bq kg-1) are equivalent to 1.5 and 3.1 times of the world average natural radioactivity levels in soil, respectively, while the mean U (34.7 Bq kg-1) is similar to the world average. The mean radiological risk assessments like radium equivalent, gamma specific activity index, external hazard index, internal hazard index, absorbed gamma dose rate, annual effective dose equivalent, annual gonadal equivalent dose, and excess lifetime cancer risk are 213.96 Bq kg-1, 0.78, 0.58, 0.67, 97.24 nGy h-1, 119.25 µSv y-1, 684.39 µSv y-1, and 0.42 (10-3), respectively. Th consistently correlated most to the risks. We attribute the occurrence of Th to the presence of allanite, K to fertilizer use for farming, and U to both the allanite and farming. The results of our study can provide important baseline data for future detailed studies or monitoring of the long-term effects of elevated radiation levels to the local population of Erawan.

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Section: Radiometric Anomalies and Source Identificationmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

<em>In situ</em> Ground Radiometric Survey and Risk Assessments of Allanite-Bearing Beach Sands in Erawan, Palawan

Diwa¹,

Vargas²,

Tabora³

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

“…The allanite-(La) was previously characterized by Dingle et al (2019) for elemental, radiometric, and structural properties using x-ray fluorescence spectrometry, gamma-ray spectrometry, and XRD, respectively. Radiometric dating using gamma-ray spectrometry estimated the age of the allanite mineral to be around 24-35 million years.…”

Section: Sample Descriptionmentioning

confidence: 99%

“…Bulk sample collection and allanite mineral separation were described in a study by Dingle et al (2019). Pulverized grains were heated in a furnace for 1 h at 450, 650, and 850 °C in atmospheric conditions.…”

Section: Sample Collection and Preparationmentioning

confidence: 99%

“…Since allanites have varying elemental compositions, REE content, and extent of radiation damage, this study hopes to present heating effects in allanite samples from San Vicente, Palawan, Philippines, which are non-metamict and are relatively young. It has an estimated geologic age of 24-35 Ma and acquired an absorbed α-dose of 2.84 × 10 14 α-decays/mg (Dingle et al 2019). Given that the allanite has been exposed to an amount of α-radiation across geological timescales, it is assumed that there will be the presence of localized damage within the crystal structure and heating may improve the localized damage, hence this work.…”

Section: Introductionmentioning

confidence: 99%

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Heating Effects in the Structure of Non-metamict Allanite-(La) from Palawan, Philippines

Dingle¹,

Jecong²,

Olivares³

et al. 2021

Philipp J Sci

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Allanite is one of the most common sources of rare-earth elements (REEs) and contains significant amounts of thorium (Th) and uranium (U). The presence of radioactive Th and U nuclides in the mineral exposes it to long-term radiation. Like other natural minerals containing Th and U, allanite can be used as a natural analog to understand the long-term radiation effects in high-level nuclear waste (HLW) matrices. Allanite group mineral is generally found in the amorphous phase due to structural damage induced by self-irradiation. In this work, crystalline allanite-(La) samples collected in San Vicente, Palawan, Philippines – having a low absorbed -dose of ~ 1014 α-decays/ mg – were heated at 450, 650, and 850 °C to study the response of non-metamict allanite to heating at elevated temperatures, particularly at the early stages of exposure to alpha-particle radiation. An increase in structural order was observed upon heating to 450 and 650 °C, which is exhibited by a decrease in the unit cell volume by 1.6% and a decrease of the full width at half maximum (FWHM) of selected Bragg planes. It was evident that certain Bragg planes respond differently to the annealing temperatures with preferential reorientation. After annealing at 850 °C, however, the loss of OH bonds was observed in the infrared (IR) spectra, and the broadening of Bragg peaks was seen in the x-ray diffraction (XRD) patterns, suggesting an onset of structural degradation. Surface cracks are also seen in the scanning electron microscope (SEM) images. The study shows that the non-metamict allanite-(La) mineral structure responds to heating similarly to that of metamict ones reported in the literature. This study will provide data on the properties of allanite as part of the ongoing studies on radiation damage in silicate matrices.

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Determination of the REE content, geological age, and absorbed alpha dose of allanite mineral from Palawan, Philippines

Cited by 2 publications

References 23 publications

<em>In situ</em> Ground Radiometric Survey and Risk Assessments of Allanite-Bearing Beach Sands in Erawan, Palawan

<em>In situ</em> Ground Radiometric Survey and Risk Assessments of Allanite-Bearing Beach Sands in Erawan, Palawan

Heating Effects in the Structure of Non-metamict Allanite-(La) from Palawan, Philippines

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