scholarly journals Hydrothermal REE fluid-mineral reaction paths in critical mineral deposits

2021 ◽  
Author(s):  
Alexander Gysi
2020 ◽  
Author(s):  
Robert G. W. Seidel ◽  
John C. Bridges ◽  
Thomas Kirnbauer ◽  
Sarah C. Sherlock ◽  
Susanne P. Schwenzer

<p>We present results of an ongoing petrologic and modelling study of a new Martian analogue rock: The Frankenstein Gabbro (Odenwald, Germany). Our aim is to predict mineral reaction paths and fluid properties during hydrothermal alteration of basaltic host rocks on Mars – thought to be a common by-product of impact cratering – in order to assess the habitability of the fluids for the potential of Martian life, and establish a link between habitable fluid conditions and secondary mineral assemblages.</p><p>Primary minerals of the analogue are mostly plagioclase (~70 vol.%) and clinopyroxene (~20 vol.%) with lesser percentages of amphiboles and Fe-oxides. We focus on a chloritic-propylitic alteration event associated with hairline fault planes and mineral veinlets. The secondary mineralisation shows strong small-scale variability, depending on host mineral and type of fluid pathway: For plagioclase hosts, fault planes are dominated by chlorite with additional epidote and prehnite, while mineral veinlets consist of albite ± calcite ± chlorite ± epidote ± K-feldspar ± mica. For clinopyroxene hosts, fault planes consist of actinolite with additional chlorite or vermiculite, while mineral veinlets consist of prehnite and vermiculite.</p><p>We use the software CHIM-XPT to model mineral reaction paths, with published XRF bulk rock data, EMP analyses of single minerals, and a starting fluid enriched in Na, K, Mg and Si for input, the latter based on calculated element budgets of mineral replacement reactions. Our models reproduce secondary assemblages related to plagioclase-hosted fault planes (chlorite–epidote–prehnite) and veinlets (albite–chlorite–epidote–K-feldspar–mica), as well as alteration rims around clinopyroxene related to fault planes (actinolite–chlorite). Corresponding fluid conditions are ~200–250 °C, pH ~6.5–8.0, at water/rock ratios >3000, in agreement with pre-model constraints by mineralogy. The breakdown of clinopyroxene and plagioclase releases large amounts of Ca, with calcite inferred to be a late-stage product of cooling. Fluid redox state is shown to be largely controlled by host minerals, and in turn exerts strong influence on secondary mineral formation: clinopyroxene releases Fe<sup>2+</sup> during alteration, which is taken up by chlorite; in contrast, plagioclase contains up to 0.5 wt.% Fe<sup>3+</sup> substituting for Al, which is taken up by epidote. Prehnite, of the same elemental composition except for Fe, is inversely correlated with epidote. Thus, the relative percentages of chlorite, epidote and prehnite can serve as indicators of redox state in similar types of rock.</p><p>Our models match key petrological observations and provide information about the alteration process beyond what may be directly observed. They illustrate the need to account for small-scale variability, and to adjust models on a case-by-case basis. This has important implications for models of Martian habitability, where similar features may be expected. Next, we will apply these reaction pathways to Martian rocks (shergottitic basalts), focusing especially on small-scale distribution of dissolved iron species, a suggested energy source for hypothetical microbial Martian life.</p>


Resources ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 50
Author(s):  
Ewa Lewicka ◽  
Katarzyna Guzik ◽  
Krzysztof Galos

Sufficient supplies of critical raw materials (CRMs) for rapidly developing technologies, e.g., Li-ion batteries, wind turbines, photovoltaics, digitization, etc., have become one of the main economic challenges for the EU. Due to growing import dependency and associated risk of supply disruptions of these raw materials from third countries, there is a need to encourage their domestic production. This is an important starting point for EU value chains crucial for the sustainable economic growth of the whole Union. This contribution has evaluated the possibilities of CRMs supply from the EU’s primary sources. A three-step approach, including an assessment of CRMs’ importance for the EU’s economic growth, their significance in at least two of the three strategic industrial sectors (i.e., renewable energy, e-mobility, defense and aerospace), and their potential availability from EU mineral deposits, has been applied. Results of the analysis have shown that, of 29 critical mineral raw materials (according to the 2020 EC list), the potential to develop manufacturing from the Union mineral deposits exists for 11 CRMs, i.e., cobalt, graphite (natural), HREE, LREE, lithium, magnesium, niobium, PGMs, silicon metal, titanium, and tungsten, while some other CRMs, namely gallium, germanium, indium, and vanadium can be recovered as by-products. Measures to mitigate EU import dependency have been also proposed.


Author(s):  
Nikolay Tymchenko ◽  
◽  
Nataliia Fialko ◽  

The issues of the global threat seeing depletion of the main types of traditional fossil energy resources were analyzed. The data is given on the proven world reserves of these energy resources and the timing of their depletion. The theory of M.K. Hubbert on the depletion of mineral deposits is considered. The application of the theory to assess the reserves of fossil energy resources in different countries is analyzed.


2018 ◽  
Vol 62 (6) ◽  
pp. 668-673
Author(s):  
Litvinenko M.V. ◽  
◽  
Vasyutinsky I.Yu. ◽  
Sladkopevtsev S.A. ◽  
◽  
...  

2019 ◽  
Vol 145 (3/2019) ◽  
pp. 92-97
Author(s):  
Yu.V. Kirichenko ◽  
A.S. Kashirskiy ◽  
G.S. Ivaschenko

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