Geological and Mining Potential of Ecuador

Geological and Mining

Potential of Ecuador by:

John E. Bolaños (P.Eng. Geologist, M.Sc., M.C.S.M., Q.P. Geo)

March 2010

Gold Nugget of 300 g , from Rio Blanco, Azuay,

Photo: RA Jemielita, 1992 Phreatic volcanic explosion, Pichincha volcano, 1999, Photo: Public Domain

Coarse placer gold, Napo River, 1999.

Photo: J. Bolaños

Ecuador

Location Map

Ecuador comprises

650 Km of the N

portion of the

Andes

It is located to the N

of the

Huancabamba

oroclinal deflection

It is part of the

Circum-Pacific Fire

Belt

GEOLOGICAL AND MINING POTENTIAL OF ECUADOR

• The geological literature of Ecuador starts in 1892 when Teodoro

Wolf published the study “Geography and Geology of Ecuador”.

• After Wolf, several authors published various geological papers

describing geological and mineralogical targets in Ecuador (i.e.

Holloway, 1932 among others).

• Later, during the 60´s to the 90´s, Ecuador signed international

agreements for technical cooperation with several countries such as

U.K., Japan, Belgium, Germany, etc.

• One of the most productive programs carried out in Ecuador was the

“Environmental Control and Mining Development Project”

(PRODEMINCA) carried out during 1997 and 1999 with the

participation and financing of the World Bank and the Governments

of U.K., Sweden and Ecuador.

BRIEF HISTORY OF THE GEOLOGY

Geological Map of the Republic of Ecuador, Scale: 1:1.000.000

British Geological Survey and CODIGEM , 1993

Tectono -Metallogenic Map of the Republic of Ecuador, Scale: 1:1.000.000

British Geological Survey and CODIGEM , 1993

Primary Auriferous Potential Map of Ecuador (Fungeomine – Capemine 2008)

Simplified geological map of the Andes of

Ecuador, focusing on Tertiary arc

magmatic units.

One main conclussions is: “The spatial-

time distribution of the Cu porphyries and

related epithermal mineralizations of the

Peru metallogenic belts are very similar to

those ones in Ecuador.

Inset adapted from Meschede & Barck-

Hausen (2001); main map adapted from

Litherland et.al. (1994), Steinmann (1977),

Dunkley & Gaybor (1977), Mc Court et al.

(1977), Pratt et al. (1997), Hughes et al.

(1988), and Palacios et al. (2008).

(Ph.D. Thesis Geochronology,

Gechemistry, and Isotopic Composition of

Tertiary Porphyry Systems in Ecuador.

Philip Shütte, 2010, University of Geneve)



From West to East Ecuador

counts with 6 geo-structural

domains:

1. The Fore Arc Basin of the

Coast

2. Western Cordillera

3. Interandean Graven

4. Real or Central Cordillera

5. Eastern Subandean Zone

6. Back Arc Basin of Iquitos

(Figure after Litherland and Zamora 1991)

GEO-STRUCTURAL DOMAINS (Terranes)


• Is the lower and flat zone to the W.

• Cretaceous to Cenozoic basin

underlain by aloctonous basaltic

ocean crust (Ocean Piñon

Terrane).

• Geo-mining potential:

Fe+Ti+PGMs sedimentary

(Esmeraldas and Manabi)

Au+Fe+Cu placer deposits related to

rivers on the W of the Western

Cordillera.

Au+Sb+Hg+Ba Epi-Mesothermal

deposits to the S of the Coast (El oro).


1. The Fore Arc Basin of the Coast


2. Western Cordillera

• Mountain chain parallel to the Andean

bearing.

• Located between the fore-arc of the Coast and

the graven or interandean central valley.

• Formed by an accretionary prism mainly of

ocean crust composition, continental crust and

accreted Late Mesozoic to Cenozoic ocean

terrains (Piñon, Pallatanga, Macuchi).

• It is overlain by calc-alkaline Post-Eocene

continental margin volcanic sequences.

• Geo-Mining Potential:

Au+Pt placer deposits (i.e. rivers in Toisan

Cordillera).

Au+Ag+Cu+Fe VHMS as those in the Macuchi

Unit.

Cu+/-Au+/-Mo porphyry deposits (Imbabura,

Bolivar and Azuay).

Au+ Cu High Sulphidation Epithermal Deposits

(Macuchi Unit). (Figure after Litherland and Zamora 1991)


3. Inter-Andean Graven

• It is a graven valley bounded by

regional faults with Andean bearing.

• Formed by thick and large Oligocene

to Miocene volcano-sedimentary

sequences that cover the Chaucha,

Amotape and Guamote terrains with

great mining potential.

• Au+Ag+/-Cu+As+Sb+Hg Epithermal

deposits (Azuay and Loja).

• Cu+Mo+/-Au+/-Zn+/-Bi Porphyry

deposits to the S of Ecuador

• Au+Ag+Cu+Zn+Pb Epi-Mesothermal

deposits to the S of Ecuador.

• Sn+W associated to S type

Granitoids in the Amotape terrain.

• Cu+Ni+Co+/-Cr+PGM´s deposits

associated to ultramafic rocks and

ophiolite complexes mainly in the

Amotape terrain.

• Fe+Cu+Zn+/-Pb+Au VHMS related to

the Amotape terrain.

• Cu+-Zn+Pb+Ba desposits related to

granitoids on the Guamote division.


• Formed by several litho-tectonic divisions of

Andean bearing and separated by regional

faults.

The Guamote division of flysch sediments,

bounded eastwards by the ophiolitic Peltetec

fault.

The Alao division, a mid-Jurassic oceanic

island arc terrane bounded eastwards by the

Baños fault.

The Loja division, a Triassic S-type biotite

granite batholith with flanking semi-pelitic

lithologies.

The Salado division of plutonic and island

arc lithologies.

The Zamora division of continental plutonic

and volcanic rocks.

In general it comprises Pre-Cretaceous

metamorphic rocks intruded by S and I type

intrusions.

This rocks are covered by Cenozoic volcanic.

(Figure Litherland et. al. 1994)

4. Real Cordillera

• Assosiated to the Alao Division are:

Ag+Au+Sb+Pb+Zn Epithermal deposits.

Fe+Cu+Pb+Zn+Ag+Au VHMS

Cu+Au+/-Mo Porphyry deposits

PGMs+Au deposits associated to mafic and

ultramafic intrusions.

• Associated to the Loja Division (a Triassic S

type intrusive) are:

Sn+W in S type granitoids.

Cu+Ag+Pb+Zn+Sn+/-W breccias bodies.

Au+Ag+Cu+As+Zn+Pb+Sb epithermal

deposits.

• Associated to the Salado Division (plutonic

and island arc lithologies) are:

Au+Cu+Mo+Pb+Zn skarn klippes.

Cu+Au epi-mesothermal deposits related to

porphyries.

(Figure Litherland et. al. 1994)

4. Real Cordillera


• Summary of the Pre-Cretaceous geology of the Cordillera Real and sub-Andean zone (Jemielita and Bolaños, 1993)

DIVISION

(west to east)

GUAMOTE

P E

L

T

E

T

E

C

F

A U

L

T

ALAO

B A

Ñ

O

S

F

A U

L

T

LOJA

L L

A N

G A

N A

T E

S F

A U

L T

SALADO

C O

S A

N G

A –

M E

N D

E Z

F

A U

L T

ZAMORA

SUBDIVISIONS /

LITHOLOGIES

Dark and pale

orthoquartzites

with slate/shale

bands

Peltetec:

dismembered

Ophiolite

Maguazo:

Turbidites.

Alao-Paute:

Andesitic

green-stones,

tuffs and

sediments.

Tres Lagunas:

biotite (garnet)

granite and

orthogneiss

Sabanilla:

Ortho-and

paragneiss,

associated with

semipelitic

phyllites, schists

and paragneisses.

Azafran: calc-

alkaline batholith

chain

(diorite/granodiorite

)

Upano: andesitic

greenstones, tuffs

black phyllites,

graywackes and

minor marbles.

Abitagua: calc-alkaline

batholith chain.

Misahualli: andesites,

dacites, basalts, and

agglomerates.

Isimanchi: marbles and

volcano-sedimentary

rocks.

TECTONO

METAMORPHIC

STATE

Very low grade

rocks overthrust

W

Low grade

rocks, steep

fabrics,

upright folds

Low to medium

grade rocks thrust

E with

imbrications.

Low grade rocks

thrust E with

imbrications. High

level skarnfield and

serpentinite klippes

Essentially undeformed

and unmetamorphosed

AGE

Upper Jurasic ? Upper Jurasic

(Callovian-

Oxfordian)

? Triassic plutons

in

?Palaeozoic

sediments

Jurassic, with

possible pre-Jurassic

elements

Isimanchi: Triassic

Igneous rocks: Jurassic

INTERPRETA-

TION

Continetal

sediments /

Clastic wedge

Ocean Floor,

forearc and

volcanic arc or

marginal basin

S-type granites in

continentally –

derived

sediments

I-type plutons in

volcano-

sedimentary

sequence

Continental I-type

plutonic-volcanic arc


Possible collision model to account for the disposition of the individual lithotectonic divisions

(Aspden and Litherland, 1991)


5. Eastern Subandean Zone

• It comprises the Eastern slopes

of the Andes Cordillera.

• It is formed by forearc belt of

the basement covered by

volcano-sedimentary

sequences.

• It is intruded by large “I” type

batholiths.

• To the N of this zone there is

the Cordillera del Cutucu, an

uplifted zone that host

important prospects of

Au+Cu+other.

• To the S there is the El Condor

Cordillera which counts with

tremendous mineral

discoveries of

Au+Cu+U+others.


6. Back Arc Basin of Iquitos

• It comprises the Oriente or Amazonian

basin mainly form by sedimentary and

volcano-sedimentary sequences.

• It hosts the most important oil field of

Ecuador.

• Associated to it there are important

Au+Fe placer deposits.

• Si deposits are associated to some

sedimentary formations.

Summary of

the Mining

Potential

related to the

geo-structural

domains

(BGS 1994 and

Prodeminca 2000).

ORE DISTRICTS

IN ECUADOR

• With PRODEMINCA

(2000) five ore districts

were described:

1. Azuay Distric (Cordillera

Occidental and Cordillera

Real),

2. La Plata District (Cordillera

Occidental),

3. Imbaoeste (Cordillera

Occidental),

4. Alao Paute District

(Cordillera Real).

5. Zamora District (Cordillera

del Condor).

(Figure Fungeomine, 2008)

3

5

4

1

2

Porphyry copper sub-belts of the

northern Andes (Modified from Sillitoe, Prodeminca, 2000)

Porphyry Cu+Mo+/-Au deposits are occurring

within the Azuay District (i.e. Chaucha,

Gaby&Papa Grande, Fierro Urcu, others),

Imbaoeste District (i.e. Junin) and Zamora

Districts (i.e. San Carlos, Cumay, Tumi, El

Hito&Santa Barbara, Mirador).

Porphyry type mineralization and intrusion

related epi-mesothermal mineralization are

known to occur within the litotectonic terranes

of the Andean Cordillera of Ecuador.

Each district has been subdivided into

mineralized belts and orefields. For example:

The Azuay District (Collay Shincata Belt,

Molleturo ore field and Ponce Enriquez

Orefield), the Zamora District (Nambija Belt,

San Juan Bosco orefield and Pachicutza

orefield).

High sulphidation epithermal

deposits (alunite-Kaolinite) have been

encountered in the Azuay District

(Gañarin Belt, i.e. Quimsacocha; and

Collay-Shincata Belt, i.e. El Mozo ,

Asaray, Cerro Colorado and Loma

Quipal projects). Some other

occurrences of this type of

mineralization have been described to

the south in the Loja Province (i.e. La

Encrucijada and Quinapalma projects)

suggesting the extension of the Collay-

Shingata belt to the south.

Low sulphidation epithermal

deposits/systems (adularia-sericite)

have been described also in the Azuay

District (Molleturo orefield i.e. Beroen

project; Gañarin Belt i.e. Gañarin

project; and Collay-Shicata Belt i.e. La

Encrucijada project).

(Figure Prodeminca 2000).

EPITHERMAL DEPOSITS

Volcanic hosted massive

sulphides have been related to

the La Plata District (i.e La

Plata and Macuchi projects)

located on the western slopes

of the Cordillera Occidental.

Another important district for

VHMS deposits is the Alao-

Paute District located In the

Cordillera Real (i.e. Pilas,

Cruzacta and Guarumales

projects). This VHMS deposits

are Sierran-Kuroko types.

Macuchi is an exception

because its characteristics of

not being strataform. (Figure Prodeminca 2000).

VHMS DEPOSITS

MINING COMPANIES IN ECUADOR

COMPANIES OF THE CONMIN

Bananas: 24,000 tpa:

30% of world’s market Source: UNCTAD

Oil: 538,000 bpd

State oil company

Petroecuador

produces 170,000 bpd Source CIA

Gold: 91,000 oz in

2000 reported from

artisinal miners,

mainly Nambija Source USGS

Corriente’s Mirador

430mt @ 0.6% Cu 0.2g/t Au

International Mineral’s Gaby

6.3m oz @ 0.63 g/t Au

Dynasty’s Zaruma

1.1 moz @14g/t Au

Iamgold’s Quimsacocha

3.3m oz @ 3.2 g/t Au

Undeveloped Properties

Aurelian’s FDN

13m oz Au @ 7.23 g/t Au

DEPOSIT TYPE MINERALIZATION RESOURCES Au Ag

JUNIN Cu-Mo-Ag qtz-py-cpy-bn-moly veins in potassic&transition 982 Mt @0.9%Cu, N/A 60 Structurally controlled emplacement of quartz

porphyry to phyllic alteration 0.04 % Mo, 1.9 g/t Ag granodioritic and dioritic porphyries

TELIMBELA Cu-Mo cpy- py, moly associated with mt in qz not available N/A N/A qtz-dioritic porphyry&dykes

porphyry stockworks and breccias

CHAUCHA Cu-Mo cpy-py bn &late cpy-moly in qtz stockworks & >120 Mt @0.5% Cu, N/A N/A tonalitic batholith, qtz porphyries

porphyry disseminations in potassic - phyllic zones 0.03 % Mo

QUINSACOCHA epith. High-sulf. py-en related to advanced argillic altyeration zone 3.3 M Oz @3.2 g/t Au, 3.3 N/A andesite flows + intra caldera dacitic domes

Au-Cu-Ag (adakitic); typical high-sulf. Alteration zoning

GABY-PAPA Au-Cu porphyry associated with breccias (py, mt matrix) in potassic 6.3 M Oz @0.63 g/t Au 6.3 N/A hbl/plag. Porphiries+tonalite intrusion

GRANDE or Na-Ca alteration zones & 0.12 % Cu

CAÑICAPA epith. High sulf. sulfides oxidized; Au anomalies not understood not available N/A N/A pre-mineralization dacites and post-min. Andesites

Au typical high sulf.-type alteration zoning

CANGREJOS Au-Cu porphyry Au associated with disseminated cpy (moly) not available N/A N/A qtz-dioritic to granodioritic intrusions punctured by

andesites + breccias; roots of eroded statovolcano?

PORTOVELO porphyry & py-cpy-si-gn vein sets; disseimsted py-mt-cpy in 1.1 M. Oz @14 g/t Au 1.1 N/A fault-bounded vein set originating from dioritic to

ZARUMA epithermal Au potassic alteration zone of porphyry granodioritic porphyy intrusions

EL MOZO epith. High-sulf. vuggy silica + argillic advanced alteration >180,000 Au Oz. 0.180 N/A porphiritic andesite lava, vulcano clastic breccias,

Au tuffs, hydrotherm. Brecccias, dacitic dykes

LA PLATA volcanog. massive sericite+silic. Halo, diss. Py, chl + epidot+qz 0,913 Mt @8,01 g/t Au, 0.23 2.52 lavas and andesitic tuff

sulfide Au-Ag 88.29 g/t Ag, 5.01% Cu, 0.78%Pb carbonaceous and detritical sediments

Cu-Pb-Zn 6.71% Zn (Macuchi Unit)

CURIPLAYA Au-Cu porphyry Au-cpy-py-mt in qtz stockworks & disseminations not available N/A N/A qtz-dioritic to granodioritic intrusions punctured by

in potassic - phyllic zones andesites + breccias; structurally controlled

SAN high - grade sphal.-py-pyrrhot.-galena-Aspy-cpy-boulang. + >55,000 T@20 Oz/t Ag N/A 1.1 veins hosted in porphiritic andesitic lavas

BARTOLOME polymetallic vein qz-rhodochr.-dolomit. Carbonat. In veins 2.9%Zn, 1.15% ZPb +/- Au and volcanics of Saraguro Formation

system

MOLLETURO high - grade native silver, electrum, pyrite, sphalerite, galena 392 g/t Ag, 3.4 g/t Au, N/A N/A Younger granodiorite and quartz diorite intruding

polymetallic vein pyrrhotite, arsenopyrite, tetrahedrite, chalcocite 0,69%Cu, 2.3%Pb, 4.24% Zn the volcanic Macuchi Unit. Mineralization

system and covellite in E-W vein system

FRUTA DEL high grade chalcedonic to crystalline quartz, mangan.-carbonat. 58.9 [email protected] g/t Au, 11.8 g/t Ag 13.7 22.34 The gold-silver mineralization at FDN is associated

NORTE intermediate- calcite, adularia, barite, marcasite, total 13,689,500 Au Oz. with veins, stockworks and disseminations, mainly

sulphidation- gold pyrite as well as subordinate sphalerite, galena, in moderately to intensely silicified Misahuallí

epithermal deposit cpy with trace tetrah. and other silver sulphosalts Andesite. Silicification and gold-silver

mineralization are well developed at and below

the basal contact of the Suarez Formation

MIRADOR Cu-Au porphyry early Mo, early Cu+-Au and later copper gold stages 438 Mt @ 0.61 % Cu, 0.19 g Au/t 2.67 22.4 well defined alteration zonong, quartz-sericite

(Corriente Mo is associated with early qz veining, both copper- 1.59g/t Ag,total measured and overprintig K alt. Covering a large part of the wall

Resources Inc) gold events are sulphide dominated indicated resources categorization rock and qtz diorite porphyry.

RIO BLANCO low sulfidation quartz veins with calcedonic massive silica, banded 2.1 Mt @ 9.5 g Au/t, 69 g/t Ag 0.64 4.66 lavas and volcaniclastic rocks of predominant

epithermal veins and colloform textures with Au- electrum -py-Aspy- total measured and indicated andesitic composition (Saraguro Formation)

galena-pirargirite. resources

Total 28.120 113.02

ECUADOR MAIN DEPOSITS -Geological settings.

LITHOLOGY

IN SITU M Oz

3 FRUTA DEL NORTE DEPOSIT

October, 2009

FDN - Location and Concessions

Intermediate

sulphidation

epithermal

mineralisation:

quartz-carbonate-

sulphide

stockwork veining

& brecciation.

FDN

Deposit

Geology

Andesite

Conglomerate

Late Andesite

125m

350m

? 250 m @ 35.18 g/t Au

and 27.1 g/t Ag

MIRADOR PROJECT, LOCATION MAP

Concessions

4 copper deposits with a total of

25 billions of pounds (cut-off of

0.4% Cu)

Similar Geology, simple

mineralisation

South sector > Cu-Au, north zone

> Cu.

Mineralisation identified by soil /

sediments geochemichal survey.

OTHER MINERAL

OCCURRENCES

IN ECUADOR

PRODEMINCA, 2000

OTHER MINERAL

OCCURRENCES

IN ECUADOR

MINERAL DEPOSITS IN ECUADOR (NORTH ZONE)

MINERAL DEPOSITS IN ECUADOR (CENTRAL ZONE)

MINERAL DEPOSITS IN ECUADOR (SOUTH ZONE)

MAIN MINERAL DEPOSITS IN ECUADOR

THANKS !

[email protected]

mailto:[email protected]

Engineering

Geological and Mining Potential of Ecuador