Investor Presentaiton
EGU2020-12777
Roraima's plateau age(s)
The ages obtained from the Roraima plateau are principally
Cenozoic ranging from late Miocene to Eocene ( with the
exception of one aliquot indicating a Jurassic age), younger than
proposed in the literature.
The ages are robust and consistent for each sample. However
there is no positive correlation between the altitude and the
(U-Th)/He ages of the sample.
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Climatic implications have been demonstrated different climates
can explain the diversity of iron oxide mineralogies. Indeed the
dehydrated hematite form preferentially under warm climate and
goethite hydrated mineral are related to cooler and humid climatic
conditions (Tardy et al., 1991).
The strict differences in terms of iron oxide mineralogy, age
distribution difference and the U-Th concentrations strongly
suggest different processes in forming the duricrusts as
topographic and lithologic which are still under investigation.
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Acknowledgments Thanks to everyone who helped to this work ;
Thierry Allard, Benoit Baptiste, Claire Boukhari, Ludovic Delbes,
Alexis Derycke, Karina Marques, Maximilien Mathian, Bruno
Tourlière and Philippe Sarda
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