Hyperspectral REE (Rare Earth Element) Mapping of Outcrops—Applications for Neodymium Detection

Remote Sensing

Nina Kristine Boesche¹  Christian Rogass¹  Christin Lubitz¹  Maximilian Brell¹  Sabrina Herrmann¹  Christian Mielke¹  Sabine Tonn¹  Oona Appelt¹  Uwe Altenberger³  Hermann Kaufmann¹  Richard Gloaguen² 

[1] GeoForschungsZentrum Potsdam, Helmholtz Zentrum, Telegrafenberg, 14473 Potsdam, Germany; E-Mails:GeoForschungsZentrum Potsdam, Helmholtz Zentrum, Telegrafenberg, 14473 Potsdam, Germany;;Universität Potsdam, Karl-Liebknecht Str. 24-2514476 Potsdam-Golm, Germany; E-Mail:

关键词: rare earth elements;    imaging spectroscopy;    neodymium;    hyperspectral;    HySpex;    remote sensing;    Fen complex;   

DOI  :  10.3390/rs70505160

来源: mdpi

【 摘 要 】

In this study, an in situ application for identifying neodymium (Nd) enriched surface materials that uses multitemporal hyperspectral images is presented (HySpex sensor). Because of the narrow shape and shallow absorption depth of the neodymium absorption feature, a method was developed for enhancing and extracting the necessary information for neodymium from image spectra, even under illumination conditions that are not optimal. For this purpose, the two following approaches were developed: (1) reducing noise and analyzing changing illumination conditions by averaging multitemporal image scenes and (2) enhancing the depth of the desired absorption band by deconvolving every image spectrum with a Gaussian curve while the rest of the spectrum remains unchanged (Richardson-Lucy deconvolution). To evaluate these findings, nine field samples from the Fen complex in Norway were analyzed using handheld X-ray fluorescence devices and by conducting detailed laboratory-based geochemical rare earth element determinations. The result is a qualitative outcrop map that highlights zones that are enriched in neodymium. To reduce the influences of non-optimal illumination, particularly at the studied site, a minimum of seven single acquisitions is required. Sharpening the neodymium absorption band allows for robust mapping, even at the outer zones of enrichment. From the geochemical investigations, we found that iron oxides decrease the applicability of the method. However, iron-related absorption bands can be used as secondary indicators for sulfidic ore zones that are mainly enriched with rare earth elements. In summary, we found that hyperspectral spectroscopy is a noninvasive, fast and cost-saving method for determining neodymium at outcrop surfaces.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.