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Vermelho

Para, Brazil

Main commodities: Ni Co
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The Vermelho lateritic nickel deposit is located in the Carajás region of Para State in northern Brazil, approximately 70 km south of the iron ore mines in Carajás and only 15 km west of the Sossego Copper Mine.

The ore deposit is associated with basic to ultrabasic intrusive bodies that form a 2 to 3 km wide, NE-SW trending belt over a strike length of around 50 km, extending from Serra do Rabo on the extreme east of the Serra dos Carajas to the Pium Complex in the SW.

These bodies mainly intrude the 2.8 Ga Xingu Complex gneisses and migmatites, as well as the less extensive east-west trending orthogranulites of the 3.0 Ga Pium Complex and the 2.75 Ga Plaque Suite of the Rio Maria granitoids.

All of these rocks are part of the southern portion of the Archaean Amazon craton. The Xingu Complex is interpreted to represent highly metamorphosed and reactivated rocks of the Rio Maria granite-greenstone terrane. Two main tectonic blocks are recognised. The 'southern block' is occupied by the Rio Maria terrane, composed of the Andorinhas Supergroup greenstones and the Rio Maria, Mogno and Parazonia granitoids which grade north into the undifferentiated Xingu Complex metamorphics. The WNW trending 'northern block' (or Itacaiunas Belt) is composed of the 2.75 Ga volcano-sedimentary rocks of the Itacaiunas Supergroup (of the Carajás Basin) and the overlying platformal sandstones and siltstones of the 2.0 to 1.9 Ga Rio Fresco Group, intruded by anorogenic granites. The Itacaiunas Supergroup overlies undifferentiated metamorphic rocks equated with the Xingu Complex. Successive Archaean to Paleoproterozoic basic magmatic events are represented in the region, including the Vermelho ultrabasic suite whic parallel a major NE-SW set of faults cutting the Xingu Complex.

The Vermelho ultrabasic suite is composed of a string of serpentinised dunites, bronzites, peridotites, pyroxenites, norites and gabbros, two of which, V1 and V2 that are composed of serpentinised dunite and peridotite underlie the Vermelho deposit. The local surrounding intruded lithologies comprise granite gneiss, quartz-diorite and amphibolites.

V1 and V2 are both of the order of 3 km in lenght and 1200 to 1500 m in width and elongated east-west within the NE-SW trending composite intrusive. Approximately 40% of the ultrabasic bodies have been serpentinised forming zones that are 450 to 500 m wide in the cores of each of V1 and V2.

The lateritic profile comprises, from the top:

i). Lateritic soil, which is a few cm thick, composed of clays and lateritic fragments, ferruginous pisolites, magnetite, weathered bedrock, etc.;
ii). Laterite, which is 0.3 to 0.5 m thick of clay and red-brown ferruginous material;
iii). Saprolite, which is around 2.5 m thick, composed of reddish brown to dark yellow clays retaining the texture of the original ultramafic protolith, divied into an upper half described as ferruginous saprolite and the lower or main saprolite;
iv). Saprolitised serpentinite, which is around 0.5 m thick an made up of partially saprolitised blocks of serpentinite separated by fracture controlled saprolitisation;
iv). Serpentinite, fresh bedrock from a depth of around 3.5 to 4 m. v). Silicate Zones, which cut the saprolite occurring as irregular veins exhibiting boxwork textures.

Two types of nickeliferous laterite are recognised,

i). Garnieritic or silicate ore with a high Ni content reaching around 2% Ni, with a low Fe but high MgO content. In 1988, half the delineated reserve was of this type, averaging 1.80% Ni, 20.51% MgO, 22.48% Fe2O3, 1.10 Fe:MgO ratio and 80 ppm Cu. This zone is found in the lower or main sparolite zone and the saprolitised serpentinite.
ii). Limonitic or oxidised ore which has a lower Ni content, around 1.1%, high Fe and low MgO content. This ore is found in the ferruginous saprolite. In 1988, the other half of the delineated reserve was of this type, averaging 1.21% Ni, 2.71% MgO, 48.93% Fe
2O3, 18.06 Fe:MgO ratio and 211 ppm Cu.

Reserves quoted in 1988 (Bernardelli and Alves) were: 43.97 Mt @ 1.50% Ni, 11.49% MgO, 35.88% Fe
2O3, 3.12 Fe:MgO ratio and 146 ppm Cu.

Proven + probable reserves quoted in 2007 (CVRD website) are: 290 Mt @ 0.8% Ni.

The scheduled annual production is estimated to be 47 000 t of contained metallic nickel and 28t0 t of metallic cobalt.

The most recent source geological information used to prepare this summary was dated: 2007.    
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.


  References & Additional Information

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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