Interpretation of the Reflectance Spectra of Lithium (Li) Minerals and Pegmatites: A Case Study for Mineralogical and Lithological Identification in the Fregeneda-Almendra Area

• Tipo: Artigo em Revista Científica Internacional
• Data: 2021

Autores

Cardoso Fernandes, J (Autor) Outra; Silva, J (Autor) Outra; Perrotta, MM (Autor) Outra; Alexandre Lima (Autor) FCUP; Ana Teodoro (Autor) FCUP; Anjos Ribeiro (Autor) FCUP; Dias, F (Autor) Outra; Barres, O (Autor) Outra; Cauzid, J (Autor) Outra; Roda Robles, E (Autor) Outra

Revista

Título: Remote Sensing

Vol. 6

Página Final: 3688

ISSN: 2072-4292

Editora: MDPI

Indexação

ISI Web of Knowledge - 37 Citações

Scopus - 41 Citações

Outras Informações

ID Authenticus: P-00V-D00

DOI: 10.3390/rs13183688

Abstract (EN): Reflectance spectroscopy has been used to identify several deposit types. However, applications concerning lithium (Li)-pegmatites are still scarce. Reflectance spectroscopic studies complemented by microscopic and geochemical studies were employed in the Fregeneda-Almendra (Spain-Portugal) pegmatite field to analyze the spectral behavior of Li-minerals and field lithologies. The spectral similarity of the target class (Li-pegmatites) with other elements was also evaluated. Lepidolite was discriminated from other white micas and the remaining Li-minerals. No diagnostic feature of petalite and spodumene was identified, since their spectral curves are dominated by clays. Their presence was corroborated (by complementary techniques) in petalite relics and completely replaced crystals, although the clay-related absorption depths decrease with Li content. This implies that clays can be used as pathfinders only in areas where argillic alteration is not prevalent. All sampled lithologies present similar water and/or hydroxide features. The overall mineral assemblage is very distinct, with lepidolite, cookeite, and orthoclase exclusively identified in Li-pegmatite (being these minerals crucial targets for Li-pegmatite discrimination in real-life applications), while chlorite and biotite can occur in the remaining lithologies. Satellite data can be used to discriminate Li-pegmatites due to distinct reflectance magnitude and mineral assemblages, higher absorptions depths, and distinct Al-OH wavelength position. The potential use of multi- and hyperspectral data was evaluated; the main limitations and advantages were discussed. These new insights on the spectral behavior of Li-minerals and pegmatites may aid in new Li-pegmatite discoveries around the world.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 33