Reading the climate signals hidden in bauxite

The dynamics of tropical weathering through time with the formation and long-term evolution of laterite associated with climatic and geodynamic forcing is still a poorly explored issue. To better access this, we focused on lateritic-bauxitic duricrusts from the well-explored, 300 m high Kaw mountain...

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Published in:Geochimica et cosmochimica acta 2022-04, Vol.323, p.40-73
Main Authors: Heller, Beatrix M., Riffel, Silvana Bressan, Allard, Thierry, Morin, Guillaume, Roig, Jean-Yves, Couëffé, Renaud, Aertgeerts, Geoffrey, Derycke, Alexis, Ansart, Claire, Pinna-Jamme, Rosella, Gautheron, Cécile
Format: Article
Language:English
Subjects:
(U-Th)/He geochronology
Earth Sciences
Goethite
Hematite
Laterite
Sciences of the Universe
Supergene
Weathering
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Summary:The dynamics of tropical weathering through time with the formation and long-term evolution of laterite associated with climatic and geodynamic forcing is still a poorly explored issue. To better access this, we focused on lateritic-bauxitic duricrusts from the well-explored, 300 m high Kaw mountain in northeastern French Guiana. Macroscopically homogeneous Fe (oxyhydr)oxides-rich subsamples were separated from 10 bulk samples. Bulk- and subsamples were investigated by mineralogical and geochemical analyses and (U-Th)/He geochronology. The samples show a large heterogeneity on the macro- and microscopic scale reflecting different stages of duricrust formation and evolution through processes of dissolution and (re)precipitation of Fe (oxyhydr)oxides. The 284 (U-Th)/He ages obtained for goethite α-(Fe, Al)OOH and hematite α-Fe2O3 range from 30.5 ± 3.1 to 
ISSN:0016-7037
1872-9533
DOI:10.1016/j.gca.2022.02.017