An Exploration Study of the Kagenfels and Natzwiller Granites, Northern Vosges Mountains, France: A Combined Approach of Stream Sediment Geochemistry and Automated Mineralogy

Benedikt M Steiner,Gavyn K Rollinson,John M Condron

doi:10.3390/min9120750

Abstract

Following a regional reconnaissance stream sediment survey that was carried out in the northern Vosges Mountains in 1983, a total of 20 stream sediment samples were collected with the aim of assessing the regional prospectivity for the granite-hosted base and rare metal mineralisation of the northern Vosges magmatic suite near Schirmeck. A particular focus of the investigation was the suspected presence of W, Nb and Ta geochemical occurrences in S-type (Kagenfels) and I-S-type (Natzwiller) granites outlined in public domain data. Multi-element geochemical assays revealed the presence of fault-controlled Sn, W, Nb mineralisation assemblages along the margins of the Natzwiller and Kagenfels granites. Characteristic geochemical fractionation and principal component analysis (PCA) trends along with mineralogical evidence in the form of cassiterite, wolframite, ilmenorutile and columbite phases and muscovite–chlorite–tourmaline hydrothermal alteration association assemblages in stream sediments demonstrate that, in the northern Vosges, S-type and fractionated hybrid I-S-type granites are enriched in incompatible, late-stage magmatic elements. This is attributed to magmatic fractionation and hydrothermal alteration trends and the presence of fluxing elements in late-stage granitic melts. This study shows that the fractionated granite suites in the northern Vosges Mountains contain rare metal mineralisation indicators and therefore represent possible targets for follow-up mineral exploration. The application of automated mineralogy (QEMSCAN®) in regional stream sediment sampling added significant value by linking geochemistry and mineralogy.

Highlights

Since 2010, the global drive for clean energy and industrial metals led to the delineation and shortlisting of a number of “critical” metals by the European Union [1]
Et Minières (BRGM) public domain data [4,5] led to the delineation of a distinct W anomaly in the Natzwiller Granite, which is located in the northern domain of the Vosges Mountains
This paper provides an economic perspective to previous research carried out on the this paper provides an economic perspective to previous research carried out on the northern Vosges northern Vosges magmatic suite

Summary

Introduction

Since 2010, the global drive for clean energy and industrial metals led to the delineation and shortlisting of a number of “critical” metals by the European Union [1]. 2017 report, high-tech metals, such as W, Nb and Ta, are of significant importance to the European manufacturing industry. Recent exploration for these metal deposits has been ongoing for more than two decades and has been predominantly focused around known prospective European Variscan belts, such as the Erzgebirge and Cornwall, and characteristic S-type granite provinces therein [2]. Minerals 2019, 9, 750; doi:10.3390/min9120750 www.mdpi.com/journal/minerals et Minières (BRGM) public domain data [4,5] led to the delineation of a distinct W anomaly in the Natzwiller Granite, which is located in the northern domain of the Vosges Mountains.

Methods

Results

Discussion

Conclusion