Novas Perspectivas de Depósitos Minerais no Escudo do Rio Grande do Sul
New Perspectives for Mineral Deposits at the Rio Grande do Sul Shield
Ouro Preto, 14/05/2014
Novas Perspectivas de Depósitos Minerais no Escudo do Rio Grande do Sul
New Perspectives for Mineral Deposits at the Rio Grande do Sul Shield
Farid Chemale Junior – UnB ([email protected])
Eduardo Camozzato – CPRM/PA ([email protected])
Ouro Preto, 14/05/2014
IG-UnB
Introduction
Geotectonic Setting of Rio Grande do Sul Shield
Mineral Deposits of the Rio Grande do Sul Shield
New Perspectives
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3/21 Chemale Jr et al. (2012)
Geotectonic Setting of Rio Grande Sul Shield
São Gabriel Terrane
Tijucas Terrane
Pelotas Batholith
Granulitc complex
Rio de la Plata
Craton
Undifferentiated
cover and granites
D
F
B
Chemale Jr et al. (2002)
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Orogenetic Cycles in the Southern Mantiqueira
Province
Hartmann et al., 2000)
Ch
em
ale
et
al., 2012
Geotectonic Setting of Rio Grande Sul Shield
Phanerozoic Evolution
After completion of the Brasiliano Orogeny (Neoproterozoic-Eopaleozoic) occurred two main tectonic events, as follow: 1. Lithosphere deformation caused by the orogenic events at margin of the Gondwana (so-called Gondwanides) during the Permo-Carboniferorous. 2. Extensional processes due to rifting/drifting of South America and Africa, during Mesocenozoic.
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Geotectonic Setting of Rio Grande Sul Shield
Mineral deposits in the Rio de la Plata Craton (Paleoproterozoic)
1. Piedra Alta Terrane Au in GB and granitoids Ni and PGE in mafic rocks and metavolcanic rocks 2. Isla Rivera Sulfides and Au associated with granitoids and shear zones 3. Nico Perez Pb, Zn, and Cu mineralization (local quartz/Au Veining) in metavolcano-sedimentary rocks. 4. Taquerembó Block Au, Mo associated with granitoids Phosphate associated with metacarbonatite Au in metavolcanics (Batovi)
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Geotectonic Setting of Rio Grande Sul Shield
Mineral deposits in the Dom Feliciano Belt
1.0-0.69 Ga Juvenile rocks
0.8-0.7 Ga and 0.65-0.54 Ga reworked rocks
SIMPLIFIED GEOLOGIC MAP OF URUGUAYAN – SUL-RIOGRANDENSE
AND SANTA CATARINA SHIELDS
Chemale Jr., 2000
SÃO GABRIEL TERRANE
T I J U C A S
T E R R A N E
Phanerozoic cover
Retro-arc basins
Pelotas Batholith
Encruzilhada do Sul Wedge
Tijucas Terrane
São Gabriel Terrane
Rio de la Plata Craton/ Luis Alves Block (SC)
30o
RS
SC
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Geotectonic Setting of Rio Grande Sul Shield
SIMPLIFIED GEOLOGIC MAP OF URUGUAYAN – SUL-RIO-GRANDENSE
AND SANTA CATARINA SHIELD
Phanerozoic cover
Retro-arc basins
Pelotas Batholith
Encruzilhada do Sul Wedge
Tijucas Terrane
São Gabriel Terrane
Rio de la Plata Craton/ Luis Alves Block (SC)
NEOPROTEROZOIC CONTINENTAL
MAGMATIC ARC WITH STONG CRUSTAL
COMPONENT (0.65-0.54 GA)
30o
RS
SC
GEOLOGIC MAP OF THE PELOTAS BATHOLITH (Phillip et al., 2000)
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Geotectonic Setting of Rio Grande Sul Shield
Mineral deposits in the Dom Feliciano Belt SIMPLIFIED GEOLOGIC MAP OF
URUGUAYAN – SUL-RIO-GRANDENSE AND SANTA CATARINA SHIELD
Phanerozoic cover
Retro-arc basins
Pelotas Batholith
Encruzilhada do Sul Wedge
Tijucas Terrane
São Gabriel Terrane
Rio de la Plata Craton/ Luis Alves Block (SC)
30o
RS
SC
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1. São Gabriel Terrane Orogenic Au. Sulfides in metavolcanossedimentary rocks. Phosphate associated with (meta)carbonatite (?) (e.g.: Tres Estradas). 2. Tijucas Terrane Cr in ultramafic rocks. Skarn deposits. Basic metals/Au associated with graphite schists. 3. Pelotas Batholith Pb, Zn, and Cu (±Au) associated with granitoids and brittle-ductile faulted zones. Speciallized granites (Sn, W, REE). 4. Camaquã Basin and associated Granitoids Sedimentary-hosted Cu, Pb, Zn (Ag, Au). Intrusion-related deposits (Au, Cu, Mo). HS and LS deposits in volcanic rocks.
Mineral Deposits of Rio Grande Sul Shield
Two geological windows in the
Uruguayan – Sul-Rio-Grandesense Shield
1. Isla de Rivera
2. Bom Jardim Window
Main mineral deposits
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Malmann et al., 2007 Quadros et al., 2002
Epigenetic mesozonal model with restrict occurrence of small deposits
Epigenetic epizonal shallow crustal levels with Au (Cu) mineralization
WESTERN EASTERN
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Main mineral deposits
Minas de Corrales
(Uruguay)
Western Sector (Minas de Corrales, San Gregório, etc.) Au Epigenetic epizonal mineralization associated with shearing processes in Brasiliano granitoids and hypabissal acid to intermediate volcanic rocks (Monteiro et al., 1991, Quadros et al., 2002). Strike-slip tectonics with channelized fluids along the ductile-brittle structures with strong hidrotermal process and Au sulfide- mineralization
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Main mineral deposits
Camaquã Basin
Camaquã Mines Pb-Zn and Cu deposits
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Main mineral deposits
Chemale et al., 2000
Almeidaet al., 2012
Chlorite-rich zone (left, East) Oxidized hematite rich zone (right, West)
Open pit of Uruguay Mine - Copper (Au) deposit
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Laux et al., 2005
Main mineral deposits
Nível 180, Mina Uruguai
subterrânea (Minas do
Camaquã, RS).
Brecha cimentada por
calcocita, em zona de falha.
Level 180, Uruguay Mine (Minas do
Camaquã, RS).
Breccia with calcocite as cement, in fault
zone (Laux ,1995)
Nível 220, Uruguay Mine (Minas do
Camaquã, RS).
Breccia witn cpy as cement, in fault
zone (Laux, 1995)
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Main mineral deposits
6.5
74
.00
0
6.5
76
.00
0
6
.57
8.0
00
6
.58
0.0
00
262.000 264.000 266.000
Pb-Zn Santa Maria Deposit , RS
Mineralization with stron structural
control (ductile-britle), associated
with transtesional zones of 2ª order.
Hidrothermal alteration contrl the
distribution of metals
Hidrothermal alteration zoning : (1)
illite Pb-Zn (2) chlorite Cu (Au).
16/21 (Samuel Lago, 2013)
Main mineral deposits
Santa Maria deposit section (Samuel Lago, 2013)
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disseminate
disseminate
Main mineral deposits
208Pb/206Pb x 207Pb/206Pb diagram for the main units of the Sul-Rio Grandense Shield and
sulphide mineralization ( ) (Takehara et al., 2010)
Pb isotope sources of the Cu and Pb-Zn sulphides are very distinct, where the Cu mineralization came from the juvenile source rocks formed during the Neoproterozoic and the Pb-Zn from crustal rocks formed in the Paleoproterozoic.
Cu mineralization
Pb-Zn mineralization
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1. Cr in ultramafic rocks
2. Skarn deposits
3. Basic metals associated with
graphite schists
•Tonalitic gneisses, amphibolites, mylonitic
granites and pegmatites formed during the
Paleoproterozoic but strongly affected by the
Neoproterozoic tectonics
•Volcano-sedimentary association with calc-
alkaline affinity formed about 0.8 to 0.7 Ga
•Volcano-sedimentary sequence formed at 600 Ma
(with ophiolite slices)
• Retro-arc volcano-sedimentary association and
granites (0.61 to 0.54 Ga)
Mineralization occurrences
Lithological Association
Tijucas Terrane
Chemale et al. (2011)
28 km
Main mineral deposits
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Sul-Rio-Grandense Shield Map with
the domic structures
Strike-slip related
Metamorphic Complex
similar to the Extensional
Core Metamorphic
Complexes (USA, QF)
Caçapava Santana
1. Strike-slip tectonics gave rise
uplift of hot crust (either Paleoproterozoic
or Brasiliano) as NE-trending elongated
dome structures.
2. Sin-tectonic sedimentation (Guaritas
Group units) and sin-tectonic fluid percolation
with mineralization of Cu, Pb and Zn (Au,Ag).
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New perspectives
1. Understand and test the work hypothesis on extensional
tectonics associated with dome structures (many deposits
are genetically related to this tectonism).
2. Detail the N-S, NNE-SSW, N60o-70oW-S60o-70oE, and E-
W trending structures because many deposits are controlled
by these structures (eg. Isla de Riveras, Camaquã Mines,
Andrade occurrence, Tres Estradas, etc).
3. Detailed studies after Cr, Ni, and PGE in mafic-ultramafic
bodies (as ophiolites of São Gabriel and Tijucas Terranes).
4. Exploration activities on the Tijucas Terranes after the
sulphide-rich graphite schists.
5. Looking after VMS and SEDEX mineralization in the São
Gabriel Terrane.
6. Exploration studies in the more differentiated granites of
the Dom Feliciano Event (650-540 Ma) after W, Sn, and
REE.
7. Looking after the Mesozoic Alkaline (or Phanerozoic)
deposits (Nb, Phosphate, REE) in the Rio Grandense Shield.
8. Additional exploration studies for the coastal sediments
(heavy minerals = Ti, REE, etc.).
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