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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

mailto:[email protected]

mailto:[email protected]

Introduction

Geotectonic Setting of Rio Grande do Sul Shield

Mineral Deposits of the Rio Grande do Sul Shield

New Perspectives

2/21

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)

4/21

Orogenetic Cycles in the Southern Mantiqueira

Province

Hartmann et al., 2000)

Ch

em

ale

et

al., 2012


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.

5/21


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)

6/21


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


Rio de la Plata Craton/ Luis Alves Block (SC)

30o

RS

SC

7/21


SIMPLIFIED GEOLOGIC MAP OF URUGUAYAN – SUL-RIO-GRANDENSE

AND SANTA CATARINA SHIELD

Phanerozoic cover

Retro-arc basins

Pelotas Batholith


Tijucas Terrane



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)

8/21


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


Tijucas Terrane



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

10/21

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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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

12/21


Camaquã Basin

Camaquã Mines Pb-Zn and Cu deposits

13/21


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

14/21

Laux et al., 2005


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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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)


Santa Maria deposit section (Samuel Lago, 2013)

17/21

disseminate

disseminate


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

18/21

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


19/21

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).

20/21

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.).

21/21

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