Kaw mountain P

The Roura-Fourgassié-Kaw mountain ridge (“Kaw mountain”) is a ca. 40 km long ridge with elevation up to 200-320 m in northeastern French Guiana. It stretches SE-NW in a convex shape parallel to the coast around 20 km away from the latter. The top of the ridge is covered by a thick lateritic-bauxitic profile which formed on top of schists of the Paleoproterozoic Paramaca formation.
The discovery of the site goes back to 1847, but most knowledge of the ore deposit results from an extensive exploration campaign in the 1950s for which ca. 55 000 samples were analyzed (Choubert, 1956). The bauxite reserve was estimated to 42Mt with a mean composition of 42% Al2O3 but commercial exploitation never took place.
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Nowadays part of the ridge is a natural reserve for the Cock-of-the-rock (Rupicola Rupicola), an endemic bird which nests in rocky areas, at Kaw often in and around the caves associated to the lateritic duricrust. Thick iron and aluminum duricrust cover the crest the Kaw mountains, which is cover by a thin soil.
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For the RECA project, in collaboration with the S2S project (BRGM and Total energies), two sampling campaigns were organized to Kaw mountain. In a first field trip in 2017, several samples of the Fe-Al duricrust were taken. In 2018, the sampling included a 75m drill core that crosses the upper part weathering profile (note that at 75m depth the unweathered rock was not yet reached!).

The samples from Kaw mountain are currently being analyzed using a number of methods and the samples from the Fe-Al duricrust are being dated by (U-Th)/He geochronology and analyzed by mineralogical methods. For selected samples, Fe isotopes were measured. The samples from the drill core were studied by classical mineralogical and geochemical methods. For selected samples clay minerals were separated and dating of the kaolinites by electron paramagnetic resonance spectroscopy (EPR) is currently being done. For the same samples Si isotopes were measured (IPG, Paris).
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Choubert B. (1956) Les Gisements de bauxite de la Guyane Française., ORSTOM Report, Congres de Mexico