Ressources en terres rares de l’Europe et du Groenland : potentiel minier et enjeux

Abstract

Les Eléments de Terres Rares sont distribués à faibles teneurs dans grand nombre de roches. Pour en augmenter les concentrations et en faire une ressource exploitable, de multiples processus géologiques sont à l’œuvre. Charles et al. font l’inventaire exhaustif des domaines européens où des concentrations intéressantes en Eléments de Terres Rares sont reconnues.

Formation of authigenic grey monazite: A palaeo-thermal anomaly marker in very-low grade metamorphic rocks?

“…Many occurrences of nodular grey monazite are known in the Americas, Asia, Europe and Africa (Rosenblum and Mosier, 1983;Charles et al, 2022) and future studies may show that they are controlled by a high heat flux that could be linked to a specific geodynamic setting or to local heat flow sources such as thermal haloes around magmatic intrusions.…”

“…It has variously been interpreted as detrital, diagenetic or anchizonal ( Čopjaková et al, 2011;Evans and Zalasiewicz, 1996;Milodowski and Zalasiewicz, 1991;Rosenblum and Mosier, 1983;Wilby et al, 2007). This is especially true for the enigmatic crystallisation of nodular monazite found in shales, which become further concentrated in palaeoplacer and placer deposits in France, Belgium, Portugal, Siberia, Spain, Taiwan, USA, United Kingdom, Iran and a number of African countries (Alipour-Asll et al, 2012;Burnotte et al, 1989;Charles et al, 2022;Cooper et al, 1983;Donnot et al, 1973;García-Tenorio et al, 2018;Milodowski and Zalasiewicz, 1991;Read et al, 1987;Rosenblum and Mosier, 1983;Salgueiro et al, 2020). Published results on the origin of nodular monazite are largely based on the structure and chemistry of nodules recovered from placers (Cobert et al, 2015;Cooper et al, 1983;Donnot et al, 1973;Milodowski and Zalasiewicz, 1991;Read et al, 1987;Rosenblum and Mosier, 1983).…”

“…With regard to its chemical composition, nodular monazite is usually enriched in MREE (mostly Eu-Gd) and low in Th and U (Alipour-Asll et al, 2012;Donnot et al, 1973;Rosenblum and Mosier, 1983). These specific characteristics make nodular grey monazite (NGM) of particular interest in mineral exploration and exploitation, because of their low radioactive content, and for the REE + Y which are a critical commodity now widely used in green technologies (Charles et al, 2022;Guyonnet et al, 2016;Lee et al, 2020).…”