New insights into mineralogy and geochemistry of allanite-bearing Mediterranean coastal sands from Northern Greece

• Autor(a) principal: Tzifas, I. T.
• Data de Publicação: 2019
• Outros Autores: Papadopoulos, A., Misaelides, P., Godelitsas, A., Goettlicher, J., Tsikos, H., Gamaletsos, P. N., Luvizotto, G. [UNESP], Karydas, A. G., Petrelli, M., Noli, F., Kantarelou, V, Kontofakas, A., Hatzidimitriou, A.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://dx.doi.org/10.1016/j.chemer.2019.05.002; http://hdl.handle.net/11449/196292
• topic: Kavala; Beach placer; REE; Thorium; Allanite; mu-XRF; SR-XANES

Allanite-bearing black coastal sands of Kavala (N. Greece) were studied using a combination of single-crystal XRD, EMPA, mu-XRF, bulk ICP-MS, LA-ICP-MS, mu-XANES and gamma-ray spectrometry. The sands are rich in REE (Sigma REE + Y: 4010 to 10,810 mg/kg), Th (236-1205 mg/kg) and other critical metals such as Nb, Ta and Co. The main REE- and Th-hosts are allanite and titanite. The allanite unit cell parameters were calculated whereas its formula was found to be (REE0.470Ca1. 499Th0.031) (Ti0.031Fe1.089+3Al1.880) (Si-2.906Al0.094O12) (OH). The mu- XANES spectra showed that LREE are present in trivalent oxidation state. Analyses of the non-magnetic sand fractions showed higher LREE (12,470 mg/kg) due to accumulation of allanite. The materials showed elevated radioactivity ranging from 885 +/- 13 to 3467 +/- 20 Bq/kg. The obtained results provide new insights on the provenance of the sands, the abundance of REE, Th, and other immobile elements, and offer new clues for potential exploration and exploitation.