Rare earth elements in the terminal Ediacaran Bambuí Group carbonate rocks (Brazil): evidence for high seawater alkalinity during rise of early animals

2020 ◽  
Vol 336 ◽  
pp. 105506 ◽  
Author(s):  
Gustavo Macedo Paula-Santos ◽  
Sergio Caetano-Filho ◽  
Jacinta Enzweiler ◽  
Margareth S. Navarro ◽  
Marly Babinski ◽  
...  
2021 ◽  
Author(s):  
Hatice Nur Bayram ◽  
Ali Erdem Bakkalbasi ◽  
Zeynep Doner ◽  
Ali Tugcan Unluer ◽  
Huseyın Kocaturk ◽  
...  

<p>Mediterranean type karstic bauxite deposits are considered as the primary source for aluminum (Al) production in Europe. During the Al production, Gallium (Ga) is extracted from the so called Bayer-liquor during the processing of bauxite to alumina. Ga, a rare metal, is widely used in modern chemistry and electronic industry. During the past decades, the worldwide demand for Ga has been continuously increasing. In Turkey, karstic bauxite deposits are generally found with shallow marine carbonate rocks which were deposited during Mesozoic period and located in Tauride Carbonate platform. Most of these karstic bauxite deposits can be hosted considerable Ga enrichments, with other immobile elements such as rare earth elements (REE), titanium (Ti), lithium (Li), and iron (Fe). This work focuses on the revealing of the potential Ga enrichments in bauxides from different deposits of Turkey (Mortaş-Doğankuzu, Konya; Küçükkoraş, Karaman; Acıelma-Yoğunoluk, Kahramanmaraş bauxite deposits). Geochemical data of major and trace elements of studied bauxite deposits show that these deposits have significant Ga enrichments (up to 72.6 ppm), as well as the REE (up to 580 ppm), Ti (up to 1.8%), and Li (up to 428 ppm) enrichments. In addition, the Ga enrichments show strong positive correlation with heavy rare earth elements (HREE) and moderate positive correlation with Al, Fe, Ti, Li and Sn elements. In this context, it can be concluded that the most probable source for Ga is rock forming aluminosilicates of the source rock due to the substitution with Al<sup>3+</sup> and Fe<sup>3+</sup>. During weathering process Ga exhibiting immobile behavior much like Al and Fe. Gallium is than incorporated into Al-bearing phases and thus enriched in the bauxite. Presence of Li content can be also interpreted as a contribution from micaceous source such as meta-carbonate rocks of Tauride platform. Moreover, geochemical association between Ga, Ti, Li, tin (Sn) and HREE can be explained by the redox and pH conditions causing other ions seperated from shallow environments.</p>


2018 ◽  
Vol 305 ◽  
pp. 327-340 ◽  
Author(s):  
Gustavo Macedo de Paula-Santos ◽  
Sergio Caetano-Filho ◽  
Marly Babinski ◽  
Jacinta Enzweiler

2004 ◽  
Vol 25 (1) ◽  
pp. 34 ◽  
Author(s):  
Gregory E Webb ◽  
Balz S Kamber

Microbes utilise and/or concentrate diverse metal cations, whose detection may become a potent tool for reconstructing microbial processes and, in particular, for establishing the genesis of ancient carbonate rocks that were produced by microbes. Such rocks, termed microbialites, consist of trapped and bound sediment and, importantly, carbonate minerals precipitated as accidental byproducts of metabolic or decay processes within biofilms. Where trace metals are predictably incorporated into microbialites, they may reflect biofilm processes and allow interpretation of preserved carbonates. Holocene (about 5-6,000 years old) microbialites that formed in reef cavities in the Great Barrier Reef (GBR) faithfully incorporated high concentrations of rare earth elements and yttrium proportional to their abundance in shallow seawater. Ancient microbialites display similar behaviour.


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