Summary:
The Maracás Project is Vanadiferous Titano-Magnetite (VTM) deposit.
The NNE-striking, ~70° ESE-dipping Paleoproterozoic Rio Jacaré Intrusion occurs throughout the 40 km long Maracás Project exploration permits. Along the strike of the Rio Jacaré Intrusion within the property, several discrete deposits or areas containing vanadium-rich titanomagnetite bodies have been defined, namely the Gulçari A (Campbell) deposit, the Gulçari A North (GAN) deposit, Gulçari B deposit (currently part of GAN), the Sao Jose deposit (SJO), the Novo Amparo (NAO) deposit and the Novo Amparo North (NAN) deposit. Each of these deposits are located at various stratigraphic heights within the Rio Jacaré Intrusion, and thus occur within different cyclic units.
The Gulçari A deposit (also referred to Campbell Pit) is hosted in the lower parts of the Upper Zone of the Rio Jacaré Intrusion, between cyclic units C1 and C6, with magnetite mineralization hosted predominantly within the C3 unit. This C3 unit comprises medium to coarse-grained gabbro containing lenses of magnetitite, magnetite-pyroxenite and pyroxenite. These lenses are interpreted to pinch out along strike (i.e. in a N-S direction), and it is within this C3 unit that the largest concentrations of vanadium-rich magnetite known on the property are found (Brito, 1984). This magnetite deposit extends for approximately 350 m along strike, is up to 150 m wide and has been intersected in drilling to vertical depths of at least 300 m, and it likely extends below these depths. The deposit has been disrupted by northwest-southeast faulting.
The magnetite-pyroxenite body at the Campbell deposit was previously interpreted as a separate pipe-like intrusion cross-cutting the gabbro (Sá, 1992), but more recently has been understood as having formed within the feeder zone of the Rio Jacaré intrusion and representing one of the lower cyclic units (the C3 unit) of this intrusion.
Gulçari A Norte (GAN) Deposit
The GAN deposit is located immediately to the north of the Campbell deposit and is considered to be a northward continuation of the upper, more continuous cyclic zones of the Campbell deposit. The GAN deposit extends for approximately 1.2 km strike, with mineralization hosted within magnetite, magnetite gabbro and magnetite pyroxenite between the C4 and C9 cyclic units. Lithologies comprise medium to coarse grained magnetite gabbro with local layers of massive magnetitite and fine to medium grained gabbro with narrow interlayers of magnetite gabbro, pyroxenite, and anorthosite. The massive magnetitite is black with 60-70% magnetic oxides and traces of disseminated sulphide (pyrite and chalcopyrite) as well as small interlayers of magnetitepyroxenite and anorthosite. The C6 magnetitite is approximately 7.5 m in average thickness and extends for a known strike length of ~1 km. The C8 magnetitite extends for approximately 350 m along strike and has with a width of up to 25 m, averaging approximately 10 m. The C9 magnetite gabbro extends for a known strike of ~1.2 km and averages 30 m in thickness. The magmatic layering and mineralized zones have strike direction of 020° with a dip ranging from 60° - 65° to the southeast. In the southern part of the deposit the main ore body is cut by fault with a northwest/southeast strike direction. All layered magmatic rocks are cute by later pegmatite dykes with a range of orientations.
Novo Amparo Norte (NAN) Deposit
The NAN Deposit is the northernmost deposit identified to date within the project area and is considered to be the northern extension of the C4 to C7 cyclic units of the Upper Zone of the Rio Jacaré intrusion.
The deposit extends for approximately 2.5 km of strike length and has been drilled in detail over approximately 1.8 km of this strike. The geology of this deposit comprises fine to medium grained gabbro and magnetite gabbro, with layers of anorthosite, magnetite pyroxenite and magnetitite. All layers strike 020° and dip approximately 70-75° SE. Mineralization is hosted predominantly in a ~10-20 m thick magnetitite layer that grades upwards into magnetite gabbro. This layer is found within the C6 cyclic unit and is made up of >60% of magnetic oxides in addition to pyroxene, amphibole, garnet and disseminated sulphides (pyrite). Small interbedded layers of magnetite pyroxenite, magnetite gabbro and anorthosite are observed within this magnetitite. At the northern end of the deposit, the mineralized zone is interrupted by a northwest-southeast trending fault.
São José (SJO) Deposit
The SJO Deposit is situated in the upper zone of the Rio Jacare Intrusion and comprises two magnetitite units in the C6 and C8 cycles, as well as an additional mineralized magnetite gabbro within the C9 cycle. The mineralized zones and other unmineralized magmatic lithologies have a strike of 020° and dip at 65° to the southeast. The magnetitite units are fine to medium grained and massive, and the magnetite gabbro is coarse grained and foliated, with a mineral assemblage composed of plagioclase and amphibole, with garnet and magnetite. The C6 magnetitite unit is on average 8 m thick has been drill tested along approximately 400 m of strike. The C8 magnetite is narrower, approximately 3 m thick, and has been tested for approximately 250 m of strike. The C9 magnetite gabbro is approximately 20 m thick and has been tested over approximately 300 m of strike.
On the east side, this deposit is hosted by magnetite gabbro and is characterized by a coarse-grained, foliated mineral assemblage composed of plagioclase and amphibole, with garnet and magnetite. The west side the ore body is in contact with a fine grained gabbro strongly foliated with narrow bands of pyroxenite. The magnetitite is dark gray to black, fine to medium grained and massive.
Novo Amparo (NAO) Deposit
The NAO Deposit is located between the NAN and SJO deposits in the upper cyclic units of the Rio Jacare Intrusion. The exact stratigraphic position of the mineralization has not yet been determined, but based on airborne magnetic data, it appears likely to be within the C8 unit. The mineralization occurs in a magnetitite to magnetite gabbro that extends for >300 m along a north-northeast/south-southwest strike, with a dip of 70° SE and widths ranging from 11 m to 21 m.
The magnetitite mineralization contains over 60% titanomagnetite, is dark gray to black and has a massive structure, with a locally developed foliation observed in the gangue minerals, which consist of amphibole, biotite, chlorite and garnet. Commonly interlayered with the massive ore are minor, thinner layers of magnetite pyroxenite, magnetite gabbro and pyroxenite.
The magnetite gabbro occurs in the western part of the deposit and is characterized by fine- to coarse-grained mineral assemblage of plagioclase, amphibole, titanomagnetite, and disseminated sulphide (pyrite and chalcopyrite). The deposit is cut longitudinally by bodies of quartz-feldspar pegmatite that cross the mineralized zone. These pegmatites have a strike direction of approximately 030° and dip at 60 - 70° to the northwest.
Mineralization
Vanadium is hosted within titaniferous magnetite, which is the major oxide phase found within the deposit. Ilmenite forms a second oxide phase which is commonly present, and which hosts titanium mineralization. Magnetite occurs as primary magmatic crystal grains that may be partly to martitized. These occur as anhedral grains, with grain sizes of between 0.3 mm and 2.0 mm, that form a polygonal mosaic together with ilmenite, which generally occurs as discrete anhedral magmatic crystals but may also occurs as inclusions within in the titaniferous magnetite, commonly displaying exsolution textures.
In addition to primary magnetite, fine-grained magnetite also occurs locally as inclusions within silicate grains.
In addition to the vanadium and titanium, elevated platinum and palladium values have been found.