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Paragominas

Para, Brazil

Main commodities: Al
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The Paragominas bauxite deposit is located 50 km SW of the town of the same name in Para State, Brazil, approximately 200 km south east of Belem (#Location: 3° 15' 51"S, 47° 43' 38"W).

It lies within the eastern Amazon region and the Maranhão Basin where it appears to have been developed in late Tertiary and early Quaternary sediments. The bauxitic zone extends over at least 1000 sq. km with an average thickness 2.2 ±1 m and estimated resources of more than 1 Gt of bauxite. Reserves in 2004 were estimated at 878 Mt (USGS).

The Palaeozoic tectonic regime in the continental interior of Brazil produced a series of large sedimentary basins, such as the Maranhão Basin. Reactivation in the Mesozoic and Cenozoic caused further uplift, resulting in substantial erosion of the Brazilian platform. The concomitant buildup of sediments in the low-lying area was extensive and continued into Quaternary time.

The Paragominas bauxite lies at the margin within the Maranhão Basin where Precambrian basement rocks are exposed. Outcropping sequences exposed outward from the centre of the basin are of Quaternary, Tertiary and Cretaceous age, although very little outcrop of fresh rock occurs in the vicinity of Paragominas. The oldest weathered bedrock in the vicinity of the deposit comprises Cretaceous sedimentary rocks of the Itapercuru Formation - arenaceous sediments cemented by kaolinised material. These are overlain by the Tertiary Barreiras Group - friable arenites, overlain by claystones and capped by mottled clay, weathered remnants of which appear at the base of the plateau scarps. These are in turn overlain by laterites of Quaternary age - containing the bauxitic deposits which are overlain by the Belterra Clay unit. Although these laterites are largely considered as being of Plio-Pleistocene age, they are in fact still undergoing formation and are still exposed to the leaching processes which have been operating for millions of years.

The lateritic profile containing the bauxite deposits comprises:

Belterra clay, 12-17 m thick - Quite porous, fine sand and clay with no obvious macro- or microsedimentary structures,
Pisolites, 1.5 m thick - Composed of pisolites which are <2 cm in diameter, containing hydrated oxides of Fe and AI,
Laterite/blocky bauxite, 0.7 m thick - Ferruginous lateritic and bauxitic blocks which are10 to 40 cm across,
Massive bauxite 1.0 m thick - Hydrated alurninum oxide (gibbsite) forming massive beds,
Blocky bauxite 1.2 m thick - Bauxite forms discrete blocks, showing evidence of development along root ways (small roots are found even in the deepest sections)
Mottled clay

The most recent source geological information used to prepare this summary was dated: 1979.    
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd.   Unauthorised copying, reproduction, storage or dissemination prohibited.


Paragominas

  References & Additional Information
   Selected References:
Kronberg B I, Couston J F, Stilianidi Filho B, Fyfe W S, Nash R A and Sugden D,  1979 - Minor element geochemistry of the Paragominas bauxite, Brazil.: in    Econ. Geol.   v74 pp 1869-1875


Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge.   It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published.   While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo takes no responsibility what-so-ever for inaccurate or out of date data, information or interpretations.

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