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Karst-bauxite formation during the Great Oxidation Event indicated by dating of authigenic rutile and its thorium content

Cabral, Alexandre Raphael; Zeh, Armin 1,2
1 Institut für Angewandte Geowissenschaften (AGW), Karlsruher Institut für Technologie (KIT)
2 Zukunftscampus (CAMPUS), Karlsruher Institut für Technologie (KIT)


Aluminium (Al)-rich palaeosols—i.e., palaeobauxite deposits—should have formed in karst depressions in carbonate sequences as a result of acidic solutions from oxidative weathering of sulfide minerals during the Great Oxidation Event (GOE), but no GOE-related karst-palaeobauxite deposits have so far been recorded. Here, we report results of in situ uranium–lead (U–Pb) dating of detrital zircon and spatially associated rutile from a metamorphosed Al-rich rock within a dolomite sequence in the Quadrilátero Ferrífero (QF) of Minas Gerais, Brazil, known as the Gandarela Formation. Rutile grains are highly enriched in thorium (Th = 3–46 ppm; Th/U ratio = 0.3–3.7) and yielded an isochron, lower-intercept age of ca. 2.12 Ga, which coincides with the final phase of the GOE—i.e., the Lomagundi event. The rutile age represents either authigenic growth of TiO$_2$ enriched in Th, U and Pb during bauxite formation, or subsequent rutile crystallisation during metamorphic overprint. Both cases require an authigenic origin for the rutile. Its high Th contents can be used as a palaeoenvironmental indicator for decreased soil pH during the GOE. Our results also have implications for iron (Fe)-ore genesis in the QF. ... mehr

Verlagsausgabe §
DOI: 10.5445/IR/1000159377
Veröffentlicht am 30.06.2023
DOI: 10.1038/s41598-023-35574-x
Zitationen: 1
Web of Science
Zitationen: 1
Zitationen: 1
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Angewandte Geowissenschaften (AGW)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2023
Sprache Englisch
Identifikator ISSN: 2045-2322
KITopen-ID: 1000159377
Erschienen in Scientific Reports
Verlag Nature Research
Band 13
Heft 1
Seiten Art.-Nr.: 8633
Bemerkung zur Veröffentlichung Gefördert durch den KIT-Publikationsfonds
Vorab online veröffentlicht am 27.05.2023
Schlagwörter Economic geology, Geochemistry, Mineralogy, Precambrian geology
Nachgewiesen in Dimensions
Web of Science
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