FEDERAL UNIVERSITY OF RIO DE JANEIRO SOCIETY OF ECONOMIC GEOLOGISTS STUDENT CHAPTER. Cu-Au and Pb-Zn Deposits at South Brazil

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1 FEDERAL UNIVERSITY OF RIO DE JANEIRO SOCIETY OF ECONOMIC GEOLOGISTS STUDENT CHAPTER Cu-Au and Pb-Zn Deposits at South Brazil Rio de Janeiro, November 14 th, 2015

2 ACKNOWLEDGEMENTS The Society of Economic Geologists (SEG) Student Chapter from the Department of Geosciences, Federal University of Rio de Janeiro (UFRJ) wants to thank Votorantim Metais Inc. and Mudador Calcário Inc. for their hospitality during mine and field visits. Students are grateful to industry sponsors of the UFRJ SEG Student Chapter, especially to those industry members attending the field trip. Thanks to Dsc. José Carlos S. Seoane (Academic Sponsor) and Dsc. Atlas V. Correa Neto professors at the Federal University of Rio de Janeiro for all the patience, shared knowledge and unconditional support during the trip. Finally, we want to thank the Society of Economic Geologists and Federal University of Rio de Janeiro for their investment and support. For us, as a Student Chapter, it is essential to keep the cooperation between industry and academy, improving the progress of knowledge about economic geology.

3 TABLE OF CONTENTS 1. Introduction Field trip participants Trip intinerary Day by day trip intinerary Trip sumaries October 19 th October 20 th October 21 st October 22 nd October 23 rd References.. 22

4 1. Introduction The SEG Student Chapter of Federal University of Rio de Janeiro organized a field trip to the Cu-Au and Pb-Zn deposits at Rio Grande do Sul State (RS), South Brazil to visit and understand some of its actual and former mineral deposits in the context of regional geology and tectonic settings. The area was chosen by the following reasons: I. Deposits are classic type Red Beds and epigenetic hydrothermal (mostly epithermal) of easy didactics, which would be easier for the students to understand during visits. II. Our university field trips are rarely located in this part of the country. This tour would provide the first contact to the geology of southern Brazil to most students. III. Professors who helped us develop the field trip are knowledgeable about the geology of southern Brazil, and have contact with professionals responsible for projects in the chosen visit sites. We believe that participating in this kind of activity helps to gather information about mineral deposits in order to apply it in the research and metal resources exploration. In fact, studying field characteristics of ore deposits is essential to understand their forming processes and strengthen future economic geologists skills.

5 2. Field trip participants Participants attending the field trip were geology professors and geology undergraduate and post-graduate students from Federal University of Rio de Janeiro and are listed in Table 1 below. Dsc. José Carlos Sícoli Seoane Economic Geology / Remote Sensoring Professor Academic Advisor SEG Fellow Dsc. Atlas Vasconcelos Corrêa Neto Economic Geology Professor SEG associated SEG Member Filipe Menezes Rocha Post-graduate student Executive Committee (President) SEG Member Maurício Bulhões Simon Post-graduate student Executive Committee (Treasurer) SEG Member André Pereira Assis Undergraduate student Executive Committee (Secretary) SEG Member Gustavo Luiz Campos Pires Post-graduate student Chapter Member SEG Member Beatriz Gomes Caetano Undergraduate student Chapter Member Not associated Fellippe Roberto Alves Bione de Araújo Undergraduate student Chapter Member Not associated Lorrana Roriz Faria Undergraduate student Chapter Member Not associated Macarena Roca Benedek Undergraduate student Chapter Member Not associated Table 1. List of field trip participants.

6 Nearby Minas do Camaquã village, RS Explanation nearby Minas do Camaquã Village, RS Municipal Park of Pedra do Segredo, Caçapava do Sul, RS

7 Caçapava do Sul, RS Uruguai mine, Minas do Camaquã, RS Municipal Park of Pedra do Segredo, Caçapava do Sul, RS

8 3. Trip intinerary The UFRJ SEG Student Chapter organized a 9-day field trip to Rio Grande do Sul State (RS), south Brazil, to visit and examine Cu-Au-Mo/Pb-Zn porphyry, skarn and epithermal ore deposits hosted by the Camaquã Basin rocks. The mining projects, mineral deposits or occurrences and regional geology outcrops are located near the cities of Caçapava do Sul, Lavras do Sul and Minas do Camaquã (Fig. 1). Figure 1. Google satellite image showing the location of Lavras do Sul, Caçapava and Minas do Camaquã cities. Google Earth Image Quickbird, 2015.

9 3.1 Day by day trip itinerary DATE ACTIVITIES OVERNIGHT October 17 Saturday Logistics trip by 930 kilometers (Rio de Janeiro, RJ Joinville, SC) Joinville, SC October 18 Sunday Logistics trip by 930 kilometers (Joinville, SC Lavras do Sul, RS) Lavras do Sul, RS October 19 Monday 9:00 AM: Review of the regional geology in the hotel lobby; 13:00 PM: Field, Topic discussion: hydrothermal and epithermal deposits. Lavras do Sul, RS October 20 Tuesday 8:00 AM: Field, Topic discussion: volcanic and metavolcanics units; end of orogenics pulses: Jaguari granite. Lavras do Sul, RS 13:00 PM: Visit the marble Mine Votorantim Inc. Field by Lavras-Bagé road: pertitics textures and stockworks. October 21 Wednesday 6:00 AM: Visit to Camaquã Mines (trip for 85 km) Caçapava do Sul, RS October 22 Thursday 8:00 AM: Visit to Mudador Limestone 13:00 PM: Camaquã Mines Caçapava do Sul, RS October 23 Friday 8:00 AM: Field, Topic Discussion: volcanic rocks, sedimentary, metavolcanic and metasedimentary. Visiti to natural heritage (geoconservation), Pedra do Segredo. Caçapava do Sul, RS October 24 Saturday Logistics trip by 990 kilometers (Caçapava do Sul, RJ Curitiba, PR) Curitiba, PR October 25 Sunday Logistics trip by 840 kilometers (Curitiba, PR Rio de Janeiro) Rio de Janeiro, RJ Table 2. Field trip schedule.

10 4. Trip summaries 4.1. October 19 th Regional Geology Overview The study area lies within the context of the Camaquã Basin, which is located at the southernmost portion of Brazil, at the Sul-Rio-Grandense Shield (Fig. 2). Figure 2. Sul-Rio-Grandense Shield simplified geological map, showing main orogenic belts, intrusive bodies and basins. Modified from Paim, et. al., The Sul-Rio-Grandense Shield corresponds to an exposed part of the Mantiqueira Orogenic System at Rio Grande do Sul. The Mantiqueira Orogenic System is a 3000 km long and 600 to 200 km wide belt, that extends from South Bahia State (Brazil) to Uruguay. It was essentially formed during Neoproterozoic to Ordovician Brasiliano orogenic cycle that also affected Archean and Paleoproterozoic units (Hasui, et. al., 2012). The origin of the Camaquã Basin remains not well explained but some hypothesis have been proposed:

11 (a) Genesis related to collisional tectonics of the Brasiliano cycle with subsequent flexural subsidence (Issler, 1985; Gresse et al., 1996); (b) Formation by the end of the Brasiliano cycle during trascurrent regional faults reactivation, generating a strike-slip type basin (Almeida et al., 1976; Machado and Fragoso-César, 1987; Brito Neves and Cordani, 1991); (c) Composite model, in which the basin was generated by initial collisional tectonics followed by an extensional deformation phase (Chemale Jr., 1993; Paim et al., 1999). Camaquã s Mineral Deposits are associated to red-bed-type conglomerates and sandstones of Vargas member of the Arroio dos Nobres formation, Bom Jardim group. They were deposited over a coastal aluvial fan system at the end of the Dom Feliciano collisional orogenesis ( Ma), in a molasse basin, limited by NE faults. Rhyolitic, dacitic and andesitic volcanism of the Hilário member also occurs at the base of the formation. The Camaquã mining district comprehends three mineralization types 1) Vein-like mineralizations, discovered in 1865 and intensely explored until 1996 in the Camaquã Mines, named São Luiz (underground mine) and Uruguai (underground and open pit), having produced about 398 Mt of Cu@1.06%, Au@0.2 g/t e Ag@8 g/t (Teixeira e Gonzalez, 1988; Remus et al., 1999). Veins eventually coalesce into stockwork oriented by NW faulting and surrounded by hydrothermal alteration halos of chloritization, sericitization and silicification (Remus et al., 1999; Ronchi et al., 2000; Bettencourt, 1972). Identified paragenesis include pyrite-chalcopyrytequartz and bornite-calcocite-hematite-barite-calcite disseminated in sandstones and conglomerates of Vargas member. Cu mineralization at Camaquã mines (São Luiz and Uruguai), occurs as pyrite-bornite-chalcopyryte (Veigel, 1989; Veigel and Dardenne, 1990); Pb-Zn mineralization with subordinated Cu occurs in the Santa Maria deposit, with a galena-sphalerite-chalcopyrite paragenesis (Veigel, 1989; Veigel and Dardena, 1990), with about 33.4 Mt of ore reserves, Pb@1.44%, Zn@1.06% and Ag@12 15 g/t (Badi and Gonzalez, 1998);

12 2) Secondary mineralizations corresponding to the oxide and cementation phases with the following associations: hematite-bornitecalcocite-covellite in the Camaquã mines and hematite-bornite-calcocitestephanite at the Santa Maria deposit (Veigel, 1989; Veigel e Dardena, 1990). The origin of the Cu-Au and Pb-Zn-(Cu)-Ag mineralizations in Camaquã are subject of much speculation. Three hypothesis are more accredited: (a) Late-diagenetic to epigenetic hydrothermal origin, with conate fluids warmed by volcanism and channelled into the NW faults (Veigel, 1989; Veigel e Dardena, 1990); (b) Epigenetic hydrothermal mineralization, with no specification of fluid sources (Ronchi et al., 2000); (c) Epithermal mineralization associated to the Lavras or Caçapava granitic intrusions (Bettencourt, 1976; Remus et al., 1999). Hydrothermal and epithermal deposits Mineral assemblages formed during hydrothermal alteration reflect the geochemical composition of ore-forming fluids. Gold is mainly transported in solution as Au/Cl and Au/S complexes. The change of physicochemical conditions such as temperature, pressure, oxygen fugacity, and sulfur fugacity are effective mechanisms for gold precipitation. Hydrothermal fluids forming epithermal gold deposits are Au-saturated in most cases. Where they are associated to Au-under saturated fluids they are called Carlin-type gold deposits (Zhu, et al., 2011). In the field, chalcedony veins were observed crosscutting an ultramafic rock with variable main crenulation cleavage direction (Fig. 3). Stockwork-like veins are commonly found in the visited outcrops.

13 Figure 3. Chalcedony stockwork-like veins cutting na altered dunite. In the area, those chalcedony veins result from calcite and barite dissolution by a more acidic (silicic) fluid, which substitutes them to chalcedony. That substitution can be identified in the field by the occurrence of bladed texture. The rock also shows vug-like texture where material was dissolved. In Tunas-Caneleiras site (Fig. 4) there is a large NW-SE silica cap vein system showing those textures. Figure 4. Quartz-chalcedony silica cap at Tunas-Caneleiras site.

14 Another visited outcrop was a fossiliferous fine and very fine sandstone, with subordinate medium to coarse sandstone and pelite (Fig. 5) from Maricá Group, São Rafael formation, that belongs to the base of the Camaquã Basin. Outcrop near the Taquarembó lineament (NE-SW). S0: 031 /33 Figure 5. Maricá Group, São Rafael formation sandstone. S0: 031 / October 20 th Jaguari Granite The Jaguari Granite is an A-type, sub-alkaline, coarse and reddish syenogranite (Fig. 6) with minimum Pb-Pb crystallization age of 544 ± 23 Ma (Gastal and Nardi, 1992). The reddish aspect indicates dissemination of hydrothermal hematite. Brittle deformation can be observed within this anorogenic granite (Fig. 7).

15 Figure 6. Jaguari Granite Figure 7. Jaguari Granite brittle deformation fracture plains (219 /87 ).

16 Visit to the Votorantim Inc. marble mine In this site, we observed a metavolcanic unit comprising ultramafic green schists hosting impure dark carbonate marble (Fig. 8). Epidote and garnet minerals can be observed with some frequency. Part of the ultramafic rocks are serpentinites. Main structures (figure 9): 153 /18 (lineation); 082 /64 (fractures); 326 /32 (main oblique movement shear zone plane). Figure 8. Votorantim Inc. marble mine. Figure 9. Oblique shear zone plane at Votorantim Inc. marble mine.

17 Field by Lavras-Bagé road: perthitic textures and stockworks The Lavras Granite ( Ma) is a pluton that is post-collisional to the Dom Feliciano Orogeny ( Ma; Silva et al., 2005) and occurs associated to the Hilario formation volcanic sequence, both carrying Au-Cu (Pb-Ag) epithermal mineralization (Gastal et al., 2015). These granites are biotite rich with minor amphibole and commonly shows perthitic texture and chalcedony stockwork-like veins with druze, cockade and comb textures (figure 10). Figure 10. Brecciated Lavras Granite with chalcedony stockworks cutting at Dourada Prospect. 4.3 October 21 st Visit to Camaquã Mines and Santa Maria deposit Located in the district of Caçapava do Sul, State of Rio Grande do Sul, the Camaquã Mines (Fig. 11, 12 and 13) have gone through several stages of

18 research, since the discovery of the first copper mineralization indications, interspersed with periods of complete or partial stoppage of mining activities. The mine is located in the central part of an intracratonic grid of NE-SW direction, limited by major faults of regional expression. Associated with these major faults occur minor ones with N50-70W attitude in which it s accommodated the main mineralization. In the area occur majorly clastic sedimentary rocks (sandstones and conglomerates) of Precambrian age (over 700 million years). The Camaquã mines are divided into two main sectors: Uruguai (open pit and underground mines) and São Luiz (underground) and by other five minor sectors named Intermediate Zone, Potreiros, Oscarino, Feliciano and Cerro das Tunas (Bettencourt, 1976). As already explained, Uruguai and São Luiz mines are Cu-Au rich, while Santa Maria deposit is Zn-Pb rich. Figure 11. Camaquã open pit mine.

19 Figure 12. Camaquã open pit and underground mines and facilities.

20 Figure 13. Stratified conglomerates at Minas do Camaquã October 22 nd Mudador limestone mine The Mudador mine is located at Caieiras region, about 7 km away from Caçapava do Sul. This mining exploits the Mudador limestone for concrete, soil correctors, animal rations and ornamental marble where geotechnical conditions are favorable. The limestone is black to grey, extremely fractured and intruded by calcite veins of lighter color, being locally brecciated (Fig. 14). These calcitic to dolomitic marbles and limestones belongs to the Passo Feio Metamorphic Complex, which is composed by a series of Paleoproterozoic rocks (Neis et al., 2012), which were intruded by the Caçapava do Sul Granitic Complex (550 Ma; Sartori and Kawashita, 1985; Leite et al., 1995). As those metasedimentary, carbonate rich rocks were intruded by the Caçapava do Sul granite, there might be skarn mineralization associated. At the mine outcrops, different barite veins generations were observed associated either to fractures and faults or to original bedding at some parts.

21 Figure 14. Mudador Mine dark limestones October 23 rd Pedra do Segredo park The Pedra do Segredo park (Fig. 15) is a geosite located near Caçapava do Sul, RS, where the younger portion of Santa Bárbara formation outcrops. The formation is an Early Paleozoic alluvial fan deposits mostly composed by polimitic conglomerates deposited near the basin margins (Borba and Mizusaki, 2003). At the visited site, there are caves where carbonate dissolution structures were observed (Fig. 16).

22 Figure 15. Pedra do Segredo park conglomerate. Figure 16. Carbonatic dissolution structures at Pedra do Segredo cave.

23 REFERENCES Almeida, F. F. M., Hasui, Y., Britto Neves, B. B., The upper Precambrian of South America. Bol. Inst. Geoc. Universidade de São Paulo. 7, Badi, W. S. R., and Gonzalez, A. P Jazida de metais básicos de Santa Maria, Caçapava do Sul, Rio Grande do Sul. In: Principais depósitos Minerais do Brasil, vol. 3- Metais Básicos não- ferrosos. DNPN, p Bettencourt, J.S., A Mina de cobre de Camaquã, Rio Grande do Sul. Tese de Doutorado. São Paulo. 175 pp. Universidade de São Paulo. Bettencourt, J. S Mineralogie, inclusions fluides et isotopes stables d oxygéne et soufre de la mine de cuivre de Camaquã - RS (un étude preliminaire) Borba, A.W. and Mizusaki, A.M.P Santa Bárbara Formation (Caçapava do Sul, Southern Brazil): depositional sequences and evolution of an Early Paleozoic post-col- 292 Borba et al. lisional basin. Journal of South American Earth Sciences, 16: Brito Neves, B. B. and Coedani, U. G Tectonic evolution of South America during the Late Proterozóic. Precambrian Research, 53: Chemale Jr., F Bacias Molássicas Brasilianas. Acta Geológica Leopoldensia, 37: Gastal, M. C., Ferreira, F. J. F., Cunha, J.U. Da, Esmeris, C., Koester, E., Raposo, M.I.B, Rossetti, M. M. M Alojamento do granito Lavras e a mineralização aurífera durante evolução de centro vulcano-plutônico póscolisional, oeste do Escudo Sul-riograndense: Dados geofísicos e estruturais. Brazilian Journal of Geology, v. 45, p Gastal, M. C. P. and Nardi, L. V. S Petrogênese e evolução do Granito Jaguari: um típico representante metaluminoso da Suíte Intrusiva Alcalina Saibro, RS. Geochimica Brasiliensis, 1 (2): Gresse, P. G., Chemale JR. F., Silva, L. C.; Walraven, F., and Hartmann, L. A Late to post orogenic basins of the Pan Africa Brasiliano collision orogen in Southern Africa and Southern Brazil. Basin research. Hasui Y., Carneiro C.D.R., Almeida F.F.M.de, Bartorelli A. eds Geologia do Brasil. São Paulo: Ed. Beca. 900p. Issler, R. S Bacia periférica Camaquã-Itajaí: Elemento tectônico desenvolvido pela tectônica de placas. In: SIMPO. SUL-BRASILEIRO DE GEOLOGIA, 2 Atas. Florianópolis. SBG. p

24 Leite, J.A.D., McNaughton, N.J., Hartmann, L.A., Chemale Jr., F. and Remus, M.V.D SHRIMP U/Pb zircon dating applied to the determination of tectonic events: the example of the Caçapava do Sul Batholith, Pedreira Inducal, Caçapava do Sul, Brazil. In: SIMPÓSIO NACIONAL DE ESTUDOS TECTÔNICOS, 5, Anais, Gramado, RS, pp Machado, R. and Fragoso-Cesar, A. R. S Deformações brasilianas do cinturão Dom Feliciano no Uruguai. IN:Simpósio Sul-Brasileiro De Geologia, 3. Atas, V.2: Neis, L., Mizusaki, A.M.P., Koester, E. and Borba, A.W Geoquímica dos metacarbonatos do Escudo Sul-rio-grandense nas regiões de Caçapava do Sul e Arroio Grande, RS. In: CONGRESSO BRASILEIRO DE GEOLOGIA, 46, Santos, Anais, Santos, S Paim, P.S.G., Chemale Jr., F. and Lopes, R.C A Bacia do Camaquã. In: Holz, M. and De Ros, L.F. (ed.) Geologia do Rio Grande do Sul. Porto Alegre. p Remus, M. D. V.; Hartmann, L. A; McNaughhton, M. J.; Fletcher, I. R. (1999) Shrimp U-Pb zircon ages of volcanism from the São Gabriel Block, southern Brazil. In: Simpósio sobre vulcanismo e ambientes associados, 1. Boletim de Resumos, p. 83 Ronchi, L.H.; Lindenmayer, Z.G.; Bastos Neto, A. and Murta, C.R O stockwork e a zona do minério sulfetado no arenito inferior da Mina Uruguai, RS. In: Ronchi, L.H. and Lobato, A.O.C. (Coords), Minas do Camaquã, um estudo multidisciplinar. São Leopoldo. p Sartori, P.L.P. and Kawashita, K Petrologia e geocronologia do Batólito Granítico de Caçapava do Sul, RS. In: SIMPÓSIO SUL-BRASILEIRO DE GEOLOGIA, 2, Anais, pp Teixeira, G. and Gonzáles, A. P Minas do Camaquã, município de Caçapava do Sul, RS. In: Schobbenhaus and Coelho (ed.). Principais depósitos minerais do Brasil.DNPM,v.III. p Veigel, R Evolução Diagenética e Mineralização Cu-Pb-Zn dos Red- Beds do Distrito de Camaquã - RS. Brasília. 185 p. Dissertação de Mestrado. Universidade de Brasília Veigel, R. and Dardena, M. A Paragênese e sucessão mineral nas diferentes etapas da evolução da mineralização Cu-Pb-Zn do Distrito de Camaquã, RS. Rev. Bras. Geoc. 20(1-4):55-67.