SEG – Student Chapter - Universidad Nacional de Colombia

Medellín Campus (Facultad de Minas)

FIELD TRIP TO THE WORLD CLASS DEPOSITS OF NORTHERN OF CHILE

(25 January – 10 February of 2014) - Report

Group photo of the field trip participants at the Escondida Mine. Back row (left to right): Sebastián Builes,

Santiago Gil, Albert Monterroza, Jhon Sepúlveda, Jorge Julián Restrepo, Esteban Moná, and two students

practitioners who accompanied us. Next down row (left to right): Carolina Amaya, Norbey Arcila, Paola Hoyos,

Oswaldo Ordónez. Next down row (left to right): David Muñoz, Paula Pacheco, Sabina Vahos, Sara Marín,

Leidy Gaviria. Who hold the banner – Front row (left to right): Sebastián Barbosa and Adriana Blanco.

Appreciating the sponsorship of the field trip

Itinerary

Day Activities Overnight

25 Jan (Sat) Travel from Medellín to Antofagasta (Chile) with stop in Lima (Perú)

26 Jan (Sun) Travel from Antofagasta to Calama Calama

27 Jan (Mon) Visit to the Chuquicamata mine (Porphyry-Cu deposit) - Codelco Norte,

Laguna Cejar (Salar de Atacama) and Valle de La Luna (Moon Valley) Calama

28 Jan (Tue) Visit to the El Tesoro mine (Exotic-Cu and porphyry-Cu deposits) and

Esperanza mine (Porphyry-Cu deposit) - Antofagasta Minerals Antofagasta

29 Jan

(Wed) Visit to the Escondida mine (Porphyry-Cu deposit) - BHP Billiton Antofagasta

30 Jan (Thu) Visit to the Candelaria mine (IOCG deposit) - Freeport-McMoran Copper and

Gold

Tierra Amarilla

(near to Copiapó)

31 Jan (Fri) Visit to the Museo Minero de Tierra Amarilla (mining museum), San José

mine (famous for the 33 miners) and Orbicular Granite (Natural Santuary)

Tierra Amarilla

(near to Copiapó)

1 Feb (Sat) Travel from Tierra Amarilla to La Serena La Serena

2 Feb (Sun) Geological transect along the Elqui River Valley La Serena

3 Feb (Mon) Visit to the El Indio - Tambo (High sulfidation gold deposits - mine closure) -

Barrick Gold La Serena

4 Feb (Tue)

Visit to the Mina Escuela El Brillador (Cu-deposit - school mine) - La Serena

University, and the 26 de Agosto mine (Cu-deposit) - Compañía Minera San

Gerónimo

La Serena

5 Feb (Wed) Visit to Carmen de Andacollo mine (Porphyry-Cu deposit) -Teck La Serena

6 Feb (Thu) Travel from La Serena to Valparaíso Valparaíso

7 Feb (Fri) Travel from Valparaíso to Santiago Santiago

8 Feb (Sat) Enjoy time in the capital city Santiago

9 Feb (Sun) Enjoy time in the capital city Santiago

10 Feb

(Mon) Return trip to Medellín

Map of field trip

Coordinates table of visited places

Place visited Latitude Longitude

Chuquicamata mine 22°21'35.89"S 68°55'58.82"W

Valle de La Luna (Moon Valley) 22°55'17.39"S 68°17'11.50"W

Laguna Cejar (Salar de Atacama) 23°30'49.08"S 68°15'3.10"W

El Tesoro mine 23°25'42"S 69°30'50"W

Esperanza mine 23°32'28"S 69°32'42"W

Escondida mine 24°17'05"S 69°05'03"W

Candelaria mine 27°30'44.34"S 70°17'27.84"W

Museo Minero de Tierra Amarilla 27°29'49.53"S 70°15'43.54"W

San José mine 27°09'27.04"S 70°29'52.37"W

Natural Sanctuary Orbicular Granite 26°58'19.91"S 70°47'43.44"W

El Indio-Tambo mine closure 29°44'52.32"S 69°58'15.14"W

Mina Escuela El Brillador (school mine) 29°48'45.90"S 71°11'32.31"W

Carmen de Andacollo mine 30°15'30"S 71°05'32"W

Field trip Participants

Name Type Company e-mail

Carolina Amaya López Undergrade Student U. Nacional de Colombia caro.geologia@gmail.com

Norbey Arcila Quintero Undergrade Student U. Nacional de Colombia narcilaq@unal.edu.co

Juan Sebastián Barbosa Mejía Undergrade Student -

Secretary

U. Nacional de Colombia jsbarbosam@gmail.com

Adriana Marcela Blanco Palacio Undergrade Student -

Vicepresident

U. Nacional de Colombia amblancop@unal.edu.co

Juan Sebastián Builes Carvajal Undergrade Student -

President

U. Nacional de Colombia jsbuilesc@gmail.com

Leidy Gaviria Montes Undergrade Student U. Nacional de Colombia legaviriamo@unal.edu.co

Santiago Gil Cardona Undergrade Student U. Nacional de Colombia sgilc@unal.edu.co

Paola Andrea Hoyos Giraldo Undergrade Student -

Treasurer

U. Nacional de Colombia pahoyosg@unal.edu.co

Sara Paulina Marín López Undergrade Student U. Nacional de Colombia spmarinl@unal.edu.co

Juan Esteban Moná Graciano Undergrade Student U. Nacional de Colombia juanes0020@gmail.com

David Muñoz Román Undergrade Student U. Nacional de Colombia damunozro@unal.edu.co

Paula Andrea Pachecho Sintura Undergrade Student U. Nacional de Colombia paulaandrea2307@gmail.com

Jhon Alexis Sepúlveda Higuita Undergrade Student U. Nacional de Colombia jasepulvedah@unal.edu.co

Laura Sabina Vahos Agudelo Undergrade Student U. Nacional de Colombia sabinavahos@gmail.com

Oswaldo Ordóñez Carmona Geology Teacher -

Academic Fellow

U. Nacional de Colombia oswaldo.geologo@gmail.com

Jorge Julián Restrepo Álvarez Geology Teacher U. Nacional de Colombia jjrestrepoa@fastmail.fm

Albert Eduardo Monterroza Ríos Industry manager Gran Colombia Gold aemonter@gmail.com

1. INTRODUCCIÓN

At the beginning of 2014, it was conducted the “GEOLOGICAL-MINER FIELD TRIP TO

THE WORLD CLASS DEPOSITS OF NORTHERN OF CHILE” of SEG – Student Chapter

of Universidad Nacional de Colombia – Sede Medellín (Facultad de Minas) (which is

composed by undergrade students of Geological Engineering) (medellin.seg@gmail.com),

that took place in the largest world mines of Cu-Mo and Au in the northern of Chile, touring

an area of approximately 2000 km in north-south direction.

The field trip started from the named II Region of Antofagasta, more specifically from the

city of Calama, where we visited the world class Cu deposit of Chuquicamata, and places

of geological interest like the Valle de la Luna (also known as Moon Valley) and Laguna

Cejar (Salar de Atacama). Continuing the trip to the south visiting the El Tesoro and

Esperanza mines, the porphyry Cu-Mo operated by Minera Escondida, the IOCG of

Minera Candelaria, the Museo Minero of Tierra Amarilla, San José mine where 33 miners

were trapped in 2010, Natural Sanctuary Orbicular Granite, besides we realize a

geological transect from La Serena to Pisco-Elqui municipality along the Elqui River Valley,

and visited the mine closure of the El Indio epithermal deposit, El Brillador school mine of

the La Serena University, and Carmen de Andacollo porphyry-Cu mine, among others,

and finally we were enjoyning the beautiful city of Santiago.

These deposits are part of the named seven metallogenic belts, which include porphyry

Cu-Mo, IOCG, high sulfidation, exotic-Cu, and other deposits types referenced by authors

of great international stature as Maksaev, Sillitoe, Perelló, and others, and evidencing the

great metallogenic potential of this western region of South America.

2. REGIONAL GEOLOGY

The geodynamic processes in northern of Chile and their lithological signatures are

preserved since the lower Paleozoic, upper Paleozoic and Jurassic times, until the present

day. In the lower and upper Paleozoic, the sedimentary basins were formed in continental

platforms environments, which were affected directly by syn-depositional metamorphism

(due to the separation and collision of Gondwana with the supercontinent Laurentia and

Báltica), which gives rise to the rocks that constitute the basement of northern Chile and

basically comprises schists of low to medium grade. Precambrian rocks have not been

report in the northern of Chile (Bahlburg, 1997). For the end of Permian age, the

Panthalassa Ocean was an active subduction margin, forming volcano-sedimentary and

plutonic rocks, until the end of the Paleozoic, where the proto-Andean orogeny began.

There is a sedimentary, volcanic and plutonic record of subduction of the Pacific plate

beneath the South American plate from Jurassic time until now (Coira, 1982). Thus, in

northern of Chile, there are igneous plutonic and volcanic rocks, the latter, interbedded

with sedimentary rocks of transitional and continental environments. Plutons of

granodioritic composition of Jurassic age are found in the Coastal Cordillera, being older

the eastern ones than the western ones; this phenomenon is because of the tectonic

erosion in the trench. The volcano-sedimentary sequences are composed of different

kinds of pyroclastic fragments and sandy and coarser sediments. In the Cenozoic, is

where the mainly intrusive bodies are mineralized which correspond to porfidic rocks of

Paleogene and Neogene ages (Damm, 1981). These plutons intruded sedimentary rocks

which where mineralized by fluids by ending stages of the magmatism. Eolic, alluvial and

transgressive marine sediments, represents Quaternary units that are mainly the cover of

Cenozoic rocks.

3. ESTRUCTURAL GEOLOGY

In the northern Chile (between 21° and 27° S), where was developed the magmatic arc of

Paleogene, are located two of the mayor fault systems of the country. The structural

pattern is determined by a series of blocks spaced apart by a fault system with orientation

NNE that constitutes the fault systems of Domeyko and to the west along to the Coastal

Cordillera, the fault system of Atacama (scielo.org.ar; 2014).

The Domeyko fault systems have orientation NNE and a long history of transcurrent

movements, both sinistral and dextral (scielo.org.ar; 2014). The Cu-Mo porphyry deposits

located on the western side of these fault systems are the representation of zone of

weakness cortical that was an important role during the later stages of the Andean

evolution.

The Atacama fault systems are the most important structures of the southern Andes

(Artenorte.cl; 2014).Its activity began during the Mesozoic with sinistral displacement

movements. Its topographical expression in the Coastal Mountains was reactivated during

the Cenozoic.

Fig 1: Schematic structural map of northern of Chile showing the location of the Atacama fault and Domeyko

fault and porphyry deposits associated with the latter (scielo.org.ar; 2014).

4. METALLOGENIC BELTS IN CHILE

There are recognized seven metallogenic belts of porphyry of Cu - Mo and Epithermal Au

deposits, their ages range from the Carboniferous to Pliocene, will be described below

(Maksaev, V. 2001; Camus, F. 2003; Sillitoe, R. Perelló, J. 2005):

A belt of upper Carboniferous to Triassic is extent for 1500 km along the Domeyko

Cordillera where eleven porphyry systems have been identified, which have suffered

erosion and are not economically exploitable showing a weak secondary enrichment; the

belt of Jurassic occur in the westernmost zone of the Coastal Cordillera. The most

important correspond to districts of Cu-stratabound deposits hosted in Jurassic volcanic

rocks of northern of Chile. There are also copper vein systems hosted by upper Jurassic

plutons; the belt of lower Cretaceous is located in the eastern flank of the Coastal

Cordillera, the bodies associated to the mineralization are porphyries of tonalitic and

dacitic compositions, there are also Cu-stratabound, Fe-deposits (magnetite-apatite) and

the IOCG deposits are related to Atacama fault system; the belt of upper Cretaceous is

located between Copiapó and Rancagua, and include mesothermal Au-Ag veins, base

metal deposits and epithermal deposits; the belt of Paleocene – lower Eocene in

comparison with the belt of cretaceous this show most amount of Cu, Mo and Au. The

larger volume of copper are located in the north end and in the youngest deposits (52 Ma),

between the 24-26° S the porphyry systems lose their continuity and are replaced by HS

or LS deposits; the belt of upper Eocene – lower Oligocene extents for more than 1400

km along the Domeyko fault zone of transpressive behavior. This belt contains the major

amounts of copper of the world. The last event (34-31 ma) is the major Cu mineralization;

in the belt of Neogene the volcanic activity occurred in 4 stages: the first of 26-22 Ma has

associated the epithermal systems; the second between 20-17 Ma is characterized by low

volcanic activity, follow by a third period between 16-11 Ma of intense volcanism

associated with epithermal systems, and finally the fourth stage between 11-5 Ma is

associated with Cu-Mo porphyry deposits.

Fig 2: Metallogenic belts of Chile (Modified from Sillitoe and Perelló, 2005).

5. GEOLOGICAL-MINERS SITES VISITED

5.1 Chuquicamata mine – Codelco Norte – Porphyry Cu-Mo – January 27th

Is the largest open pit copper mine of the world, and is located in the II Region of

Antofagasta (lat. 22°21'35.89"S, long. 68°55'58.82"W) at 16 km from the city of Calama on

the Domeyko Cordillera. It is part of the mining complex associated with Chuquicamata

Division along with Mina Sur and it is currently led by the state-owned Codelco. Their

name comes from indigenous communities “Chuquis” who lived in the area and obtained

native copper. The open pit measures are 5 km large, 3 km width and 1 km deep forming

an ellipse.

Chuquicamata is part copper porphyry deposits of the Eocene - Oligocene (40-32 Ma) belt

and his mineralization is subvertical slightly tilted to the west and is composed by Cu, Mo,

and Ag with minor amounts of Au. The deposit is located within the Domeyko fault system

and is represented by the Oeste fault, which divides to the east the ore body and to the

west the barren rock. There are early alterations located in the periphery of the deposit,

chloritic, bottom potassium and intense potassium, the latter is the most pervasive and is

the mineralization with major content of copper and molybdenum, expressed in

chalcopyrite and bornite, it also have quartz and molybdenum veins. The late alterations

are located to the west of the deposit, obey to the action of the Oeste fault and consist of

pervasive sericitic-quartz and intense potassium relict. In the late hydrothermal part,

supergen basins are generated with greater concentrations. The mine had oxides, but

these have been already exploited, currently only processed in Mina Sur, and they have

resources for a year, it should be noted that the oxides of Mina Sur are exotic generated

by gravitational fluid migration.

The mine produces approximately 800.000 ton/day of mineral and 850 tonnes Cu/day,

generally extracting sulfides of copper and molybdenum with grades of 1.4 and 0.1%

respectively. Currently the resources in the district are about 17.287 billion of tonnes. The

fine copper of Chuquicamata is with 99, 9% of purity, and they produced a copper cathode

of 165 kg that is obtained using electrochemical processes, the cathode has a retail value

of approximately USD $1100. Throughout the process the mine spends about 2000 liters

per second of water that comes from underground mountain water. This water recycle

occurs in the thickeners, and get to use a drop 9 times before it evaporates. Having more

thickeners increases the efficiency of the mine, compared to other mines in Chile, despite

being an older mine. Regarding energy, annually they used 3 GW, which is almost 20% of

spend in Chile for a year. For this supply of energy, they used coal, thermoelectric energy

(primarily) and oil.

The method of exploitation is changing from open pit to Block Caving (underground),

because currently the mine is producing 400,000 tonnes of waste rock, and since it

increases the cost and distance that must be reached to find mineralization, it generates

higher costs. The beginning of underground exploitation will be in 2018 has a lifespan

approximately until 2060.

Fig 3: A) Intense potassic alteration; B) Molybdenite veinlet; C) Exploitation advance; D) Copper cathode.

Fig 4: A) Group photo at lookout of the Chuquicamata Mine; B) Open pit; C) Beneficiation plant.

5.2 Valle de La Luna (Moon Valley) – January 27th

The Moon Valley is located in the II Region of Antofagasta (lat. 22°55'17.39"S, long.

68°17'11.50"W) at 13 km from San Pedro de Atacama inside of the Salt Cordillera and in

the edge of Salar de Atacama.

About the geology of the zone, there are Paleozoic sedimentary marine rocks; that during

the Cretaceous began to raise in the seabed, leaving the basin between the Andes

Cordillera and Domeyko Cordillera, a huge lake with saline water that slowly evaporated,

then the fluvial and eolian erosion modified the landscape. The Sal Cordillera, which is the

most remarkable of Moon Valley scenic features, is a relief generated by successive

folding the salt flat background. It consists of sedimentary rocks with salt and gypsum

outcrops; in the saline efflorescence minerals are gypsum, anhydrite, halite and other

sulfates, borates and carbonates (Monumentos. cl, 2014).

Fig 5: A); B) Different views of the Moon Valley.

5.3 Laguna Cejar (Salar de Atacama) – January 27th

It is located within the Salar de Atacama in the II Region of Antofagasta (lat.

23°30'49.08"S, long. 68°15'3.10"W) between the Andes Cordillera to the east and the

Domeyko Cordillera to the west at 17 km from San Pedro de Atacama.

The deposition of evaporites in the basin of the Salar de Atacama has lasted at least since

the Oligocene. The stratigraphically lower levels, which constitute the Salt Cordillera, have

been folded and exposed from the middle Miocene tectonic block that controls the entire

structure of the Salar de Atacama. There are two large units in the Salar de Atacama: the

core and the marginal zone. The core consists of 90% of porous halite impregnated with

rich interstitial brine in Li, K, Mg and B; around the core, the marginal zone consists of fine

salt saline sediments, rich in sulfates. The authors state that the high salt load of the feed

water is not from residual brines, because there are also other sources such as the

alteration of volcanic rocks minerals, oxidation of sulfur and sulfide of other mineralized

bodies. This suggests that most of the Li, K, Mg and S components have a common origin.

Since Li and B are almost always associated with volcanism, it can be inferred for all these

components primarily a volcanic origin, either by hydrothermal fluids or alteration of

volcanic rocks, as it has been described in northern of Chile (Hugo Alonso, 1996).

Fig 6: A) Anhydrite crystals; B) Side view of Laguna Cejar; C) Group photo.

5.4 El Tesoro Mine – Antofagasta Minerals – Exotics-Cu and Porphyry Cu –

January 28th

The deposit is located in the II Region of Antofagasta (lat 23°25'42" S, long 69°30'50" W)

at 200 km northeast of Antofagasta. Currently the mine has three open pits, Tesoro

Central, Tesoro Noreste and Mirador and it is dedicated to a mining exploitation and

production of copper cathodes.

The mine is located on the porphyry copper belt of the Eocene - Oligocene (42-31 Ma),

which represents the largest known concentrations of copper in the world. The geology is

characterized by the presence of stratified sedimentary rocks that have been intruded by

porphyritic rocks. The Mirador pit is a Cu-porphyry deposit and the others pits are

associated with exotic mineralization that consists in atacamite, chrysocolla, copper wad

and copper pitch in sub-horizontally gravel layers. Its origin is due to the Cu-rich solutions

that migrate through paleochannel from one type porphyry copper deposit exposed on the

surface and is spatially associated with the Domeyko fault system.

The mine has a capacity of processing of 9 Mt of ore/year and 75 thousand tons of

cathodes/year. The actual resources are 220 Mt of Cu (Camus, 2003).

Fig 7: A) Group photo at lookout of the Tesoro Central pit; B) Group photo with a dump truck of 300 ton; C)

Tesoro Central open pit.

5.5 Esperanza Mine – Antofagasta Minerals – Porphyry Cu – January 28th

Esperanza mine is located in the II Region of Antofagasta (lat. 23°32'28"S, long.

69°32'42"W) at 167 km northeast of Antofagasta, and 100 km southwest of Calama, in the

eastern part of the Municipality of Sierra Gorda.

The porphyry body is located in the metallogenic belt of Eocene to Oligocene associated

with the Domeyko fault system, this intruding Jurassic andesites and Cretaceous marine

sediments, the intrusive mineralized body is elongated in the N30E direction; structurally

the deposit has two main structures, the Túnel fault and Esperanza fault, the latter is the

west limit of mineralization. The alterations presents are propylitic and potassium, as

predominantly, the mineralization is pyrite, chalcopyrite, some oxides of Cu, and bornite.

The mine belongs to Antogafasta Minerals by 70% and 30% at Marubeni Corporation, this

site extracts Cu-Au and the operation began in 2008 and has reserves of 583 Mt grading

0.55% Cu, 1.22 g/t Au, and produce 314,000 tonnes/year, 190,000 tonnes fine-Cu/year,

and 15,000 Oz Au/year. The operation is done in open pit and the material is transported

to the plant by means of a conveyor belt of 4 km to the stock pile, there to the sack

grinders and the grinder balls, then is taken to float, finely continuous to the thickeners and

the pasta obtained is carried by pipeline 145 km to the port of Minera Esperanza. This is

the first large scale mine that implemented from the beginning of its operations sea water

100% of the process, pick up at the Michilla port and transporting it by 141km to the mine,

although it is an expensive technology is an innovative method contributing to the

environment and ore beneficiation process.

Fig 8: A) Esperanza Open pit; B) Stock pile; C) Potassic alteration; D) Veinlets in Esperanza porphyry.

5.6 Escondida Mine – BHP Billiton – Porphyry Cu-Mo – January 29th

The Minera Escondida deposit is a Cu-Mo porphyry located in the Domeyko Cordillera in II

Region of Antogafasta (lat. 24°17'05" S, long. 69°05'03" W) about 140 km SE of the city of

Antofagasta, in a vast arid plain between 3000-3200 m above sea level. The Escondida

mine has approximately 4500 m large, 2500 m width and 750 m of deep. This mining

operation grouped two mines: Escondida and Escondida Norte.

The systems are associated with bimodal volcanism between late Eocene to early

Oligocene that gives rise to porphyritic intrusive complex. The Cu-mineralization is marked

by the presence of bornite and chalcopyrite. The structures are represented by a series of

NS faults associated with Domeyko fault zone (Camus, 2003). The alterations consist in

the development of one late magmatic potassium phase (associated with propilitic,

silicification and potassic alterations, with magnetite, chalcopyrite and bornite) which

bounds the margins to a more pervasive propylitic of great extent (includes chlorite-sericite

and quartz-sericite alteration with chalcopyrite, pyrite and molybdenite) and advanced

argillic alteration (represented by the acid-sulfate alteration, with quartz, pyrophyllite and

alunite as mineral association). Some exploration projects like Pampa Escondida,

Escondida Este and Chimborazo have been developed in the last year with excellent

results and maybe in a future one of this will be extracted.

This mining operation is run by BHP Billiton, which owns 57.5% of the company, and has

been developing since 1991. As regards the commodities operated by that company, it

can be mentioned that the copper extracted by the company is equivalent to 6% of world

copper production and 20% of Chilean production, highlighting that exploited 1.4 million

tons of material per day of which 400,000 are copper minerals. Annually, the production is

850,000 tons of refined copper in concentrate and 180,000 ounces of Au approximately. In

addition the company realizes a leaching extraction and electrowinning that allows you to

produce 140,000 tonnes of copper cathodes/year (Camus, 2003).

Fig 9: A) Escondida Porphyry; B) Molybdenite veinlet; C) Atacamite in supergene enrichment zone; D)

Alteration models (extract from presentations); E) Enrichment zones (extract from presentations).

Fig 10: A) Blasting at the Escondida open pit; B) Group photo at lookout in the pit.

5.7 Candelaria Mine – Freeport-McMoran Copper and Gold - IOCG – January 30th

The mine is located in the III Region of Atacama near the town of Tierra Amarilla at 22 km

from Copiapó (lat 27°30'44.34"S, long 70°17'27.84"W), currently exploited Cu and Au by

open pit and also with underground method.

In terms of geology, there are two domains, one sedimentary eastward and another

intrusive to the west. Candelaria is located at the base of the sedimentary domain, which

the andesitic volcanic rocks are folded and affected by structures. Westward intrusive

bodies (diorites and granodiorites of 119 Ma belonging to Copiapó batholith) provided the

mineralizing fluids through the reservoir structures. In terms of structural geology, the area

is dominated by north-south structures, associated with the Atacama fault system. The site

of Candelaria is located east of the fault zone. Candelaria is an IOCG deposit with the

mineralization age is estimated between 110 and 115 Ma by various methods and is

related to late fluids nearby intrusive bodies. Mineralization consists of magnetite,

chalcopyrite and pyrite, at the top of the deposit is presented pyrrhotite instead of pyrite.

The gold is contained in the inner structure of chalcopyrite and pyrite lesser extent, the ore

minerals occur in veinlets, breccia fillings and dissemination in intensely altered volcanic

rocks of the unit Punta Del Cobre Fm. The volcanic rocks of Candelaria mineralization

were affected by an early potassic alteration, a superimposed sodium-calcium alteration

later stage. A retrograde phase characterized by amphibolite, chlorite, epidote, sericite and

minor clinozoicite affected the whole and finally came up with the late introduction of K-

feldspar (post-mineralization) (Maksaev, V). Portions of Copiapó Batholith to the west are

marginally affected by intense sodium-calcium alteration possibly related to mineral

formation (Marschik & Fontboté, 2001).

The mine has a production of 200,000 tons/day, which corresponds to 70,000 ton ore Cu,

inferred resources of 121 Mt to 0.570% Cu, indicated resources 110 Mt at 0.594% Cu and

measured resources of 563 Mt to 0.679% Cu, reserves are 350 Mt of ore. The company is

controlled by U.S. Company Freeport-McMoran Copper & Gold and the finished product is

a concentrate of copper.

Fig 11: A) Mirmequític texture in potassic alteration and Cpy-Mgn veinlet of an IOCG; B) Specular hematite; C)

Breccia with chalcopyrite veinlets of Punta Del Cobre Fm. D) Garnet in hosted rock.

Fig 12: A) Open pit of Candelaria mine; B) Group photo at lookout in the pit.

5.8 Museo Minero de Tierra Amarilla (Mining museum) – January 31th

The Tierra Amarilla Mining Museum is located at km 17 km from Copiapó (lat.

27°29'49.53"S, long. 70°15'43.54"W), and was opened on 18 August 2011 in order to

gather and known parts and testimonials that illustrate representative aspects of life of

Atacama Region, providing visitors knowledge about the history of the region from its

mining vocation. The permanent exhibition shows minerals mined in national sites and

foreigners, fossils, historical objects, and models of each stage of the mining operations;

as well as the rescue of their historical heritage values, in order to contribute in a manner

relevant to knowledge and consolidation of regional identity. This place has large spaces

for recreation than and scientists seeking to find a face more social and academic of the

geology and mining (El Museo Minero de Tierra Amarilla; Page web Museo Minero de

Tierra Amarilla, 2014). On this visit we were accompanied by Mr. Alejandro Aracena who

is co-founder of the museum and who represents the mining culture in the Atacama

Region.

Fig 13: A) Atacamite; B) Group photo with Mr. Alejandro Aracena (we can see behind an orbicular granite); C)

Iron meteorite exhibited at the museum; D) Orbicule with magnetic core. E) Dendritic habit of pyrolusite F)

Group photo at the entrance of the Mining museum of Tierra Amarilla G) Calcantite.

5.9 San José Cu mine – January 31th

The San Jose mine was a mining operation located in the Copiapó Province in the III

Region of Atacama (lat. 27°09'27.04"S, long. 70°29'52.37"W) at 29 km northwest of the

Copiapó city and 33 km east of Caldera city. Its exploitation began around the mid

nineteenth century; in 1840 to August 5 of 2010 (date of the incident that left 33 miners

trapped). Although initially their production was silver, at the date of its closure on average

1,200 tons of copper per year were extracted. The mine is known for the incident that

happened on August 5 of 2010, where a collapse of 700,000 tons of material in the 300

level of the mine was produced at 5 km from the mine entrance, leaving 33 miners trapped

for 70 days. Until the "San Lorenzo” rescue operation on October 13 could reach the level

where they were trapped and finally free them.

Nowadays at the mine site, there is a memorial of the events that took place in the mine

from the moment of the collapse until the rescue of the 33 miners. In the museum you can

learn about the San Lorenzo operation, see parts of the elements that were used in the

work of search and rescue of the miners. The museum San Jose mine since then has

become a place open for interested, tourists and curious of what happened there (Díaz, F,

2013; InfoBae América, 2010 and La Torre de Babel, 2010).

Fig 14: A) SEG student group at the San José Mine; B) 33 flags belonging to the country of the miners that

were trapped inside the mine for 70 days (32 from Chile and 1 from Bolivia); C) Group photo with the flags

behind; D) “We are well in the shelter, the 33”, first sign of live received from miners; E) Tour guide explaining

the situation experienced by the 33 miners.

5.10 Natural Sanctuary Orbicular Granite – January 31th

This place is located in the III Region of Atacama (lat. 26°58'19.91"S, long 70°47'43.44"W)

belonging to the Commune Caldera. It is easily accessible and is situated 11 km north of

Caldera, near Rodillo beach. This outcrop is one of the few of this type of rock found in

Chile; it was discovered in 1961 by the Chilean geologist F. Ortiz. Given its unique

character, this site was declared “Nature Sanctuary” in 1981 and is protected by

conservation laws that apply to this type of monument (Sociedad Geológica de Chile,

2013).

The body, of Jurassic age, is dyke-like with an exposed surface area of approximately 375

m2, 15 m thick, 25 m long and is enclosed in tonalitic batholith. Both hosted rock and

orbicular body are cut by diabasic dykes. The surface ratio of matrix/orbicules is 35/65;

orbicules are mainly ellipsoidal with an average axis of 7 cm and are composed of a

quartz-diorite core and a single dark shell with a predominantly radial texture composed of

equal amounts of plagioclase and amphibole accompanied by lesser amounts of

clinopyroxene, biotite and magnetite. Non-orbicular inclusions in the orbicular body are

scare (Aguirre, Hervé, and Del Campo, 1976).

The petrogenesis of the orbicular body is explained based on two assumptions: a) Non-

orbicular inclusions in the orbicular body and the core of orbicules correspond to hosted

rock xenoliths and, b) The shell of the orbicules and the matrix were generated form a

same magma during differentiation.

Fig 15: A) Contact between the tonalitic batholith and orbicular body; B); D) Orbicules; C) Triangular Orbicule;

E) Granite Orbicular outcrop.

5.11 Geological transect along the Elqui River Valley – February 2th

The Elqui River Valley occupies the northern sector of the IV Region of Coquimbo,

extending from 29°40'S to 32°10'S. Climatically located at the boundary between the

desert climate of northern Chile and central semi-arid climate of Chile ((Cabezas, Cepeda,

and Bodini, 2007) in Sanchéz and Morales, 1993).

The geology of the area is represented by pre-Tertiary intrusive rocks and Tertiary -

Quaternary sediments (gravel and sand), which are located in the flat areas. The large

existing terraces in the lower section of the valley favor agriculture and human settlement.

In this zone highlights the major crops of grapes to produce vine and pisco (VisitChile.com,

2012)

Fig 16: A) Volcanosedimentary sequence at the Elqui River Valley; B) Puclaro dam; D); E) Vineyard in the

semiarid climate; F) Grapes from a Fundo Los Nichos vineyard.

5.12 El Indio–Tambo – Barrick Gold – High sulfidation – February 3th

The El Indio – Tambo is located in the IV Region of Coquimbo in the Andes Cordillera (lat.

29°44'52.32"S, long. 69°58'15.14"W) at 160 km from the La Serena city at heights

between 4000 and 4500 m above sea level. Actually is property of Barrick Gold and is the

first voluntary mine closure in South America and it was exploited for 23 years (1979 –

2002) through open pits and tunnels with a production of 10 M oz Au at 10 g/t Au average

grade, 100 M oz Ag and 1 Mt Cu, and has been considered the classic high sulfidation Au-

Ag-Cu vein deposit.

The world class deposit is located whitin the denominated Indio-Pascua epithermal belt

which is a metallogenic belt which contains large high sulfidation deposits like Pascua-

Lama, Veladero, Indio, Tambo, etc, that are associated with a calc-alkaline volcanism

occurred between Miocene-Pliocene (12 – 7 Ma). The evolution of the epithermal system

is characterized by two main stages: alteration and mineralization. The hypogene vetiform

mineralization is hosted in acid volcanic rocks (Vacas Heladas Fm – Dacitic ignimbrites of

12 Ma) and grouped in two mineralizations stages: Cu and Au. The cupriferous stage is

reduced and is composed by enargite and chalcopyrite, and the auriferous stage is

oxidized and consists in veins filled by quartz, pyrite, and native gold. These

mineralizations stages is associated with alterations (pervasives in some cases) quartz-

sericite and advanced argilic characterized by alunite, barite, limolite, jarosite, etc. The

mineralization is structurally controlled by two mayors reverse-rigth lateral faults oriented

NNE with a dip 60° to NW (Bissig, 2001).

For the mining factor, Barrick Gold encouraged a pioneer initiative in the Chilean mining to

make the decision to close the mine according to high environmental and social standards,

implementing a program to give sustainability in agricultural regions (grape crops) and in

nearby cities (La Serena and Coquimbo), investing about USD 80 million. The Closure

Plan include two phases, the first include the demolition, rehabilitation, surface water

management (construction of canal of 5 km for the Malo River), and the second consist in

the physical and chemical monitoring of instalations, water sources, etc (Galleguillos, 2007

and http://barricksudamerica.com/cierre-el-indio/).

Fig 17: A) Enargite – Cpy vein; B) Alunite vein and tectonic breccia; C) Baritine; D) Alunite; E) Vuggy silica; F)

Native sulfur from steam heated zone.

Fig 18: A) El Indio closure mine; B) Artificial canal for the Malo River; C) Group photo with the Tambo mine

behind.

5.13 El Brillador School Mine – La Serena University – February 4th

The school mine El Brillador is located in the IV Region of Coquimbo (lat. 29°48'45.90"S,

long. 71°11'32.31"W) at 23 km from La Serena city. It belongs to La Serena University and

is sed for academic purposes where students will make their practices in underground

mining operation with emphasis ventilation, fortification, drilling and rock fragmentation,

metallurgy, basic mining and rock mechanics, as well as training services in risk

prevention activities in plant and mine.

It is represented by deposits of Cu (chalcopyrite, bornite, chalcocite, covellite, malachite,

atacamite, chrysocolla) that are hosted in a volcanosedimentary sequence, intrusive rocks

and hornfels. In the Brillador district, bodies of hydrothermal alteration are developed in

NW faults, besides in stratabound deposits and veins.

The mine was initially operated by Indians and later managed and operated by French

businessman Charles Lambert, in the nineteenth century. Today, the 26 de Agosto mine is

operated by the San Geronimo Mining Company, through lease from the 620 m to the

surface, which together with other mines processed 25,000 tonnes of copper oxides per

month and produces about 9,000 tonnes per year of copper sulfate.

Fig 19: A) Group photo in the El Brillador entrance; B) Fortification with rockbolts; C) Capacitation area with

wood doors fortification; D) Mineralized breccia; E) Calcantite mineralization.

Fig 20: A) Atacamite vein; B) 26 de Agosto open pit.

5.14 Carmen de Andacollo – Minera Teck – Porphyry Cu – February 5th

The mining company Carmen de Andacollo is located in the IV Region of Coquimbo (lat.

30°15'30" S, long. 71°5'32" W) about 55 km south east of La Serena. The district lies

within the watershed of Andacollo and is part of porphyry copper belt of Cretaceous age.

The geology of the area roughly consists of a lower volcanic unit, with mostly andesites

porphyritic, an upper volcanic unit which presents tuffs which due to its porosity allowed

the flow of mineralized solutions, a unit of intrusive rocks formed by dacite porphyry and

rhyolitic related to copper mineralization, a unit of breccia (Brecha Hermosa), and a unit of

undifferentiated rocks which we cannot tell what kind of rock it is due to the degree of

alteration present. In Carmen de Andacollo mine it is possible to observe all kind of

alterations like alteration chlorite-epidote, biotite alteration, albitic alteration, K-feldspar

alteration, quartz-sericite alteration, and kaolin-smectite-barite-siderite-montmorillonite

alterations.

The Carmen Andacollo deposit has a hybrid genesis influenced by a porphyry copper

deposit and linked by one stratabound. It is also affected by a fault system with NE

direction like as Andacollo fault and the Beautiful fault, among others. The generation of

the deposit was a result of a series of events, starting with the extensive structural

configuration, the intrusion of porphyritic dacite dikes with all alterations that besides

solutions mineralizing invasion generated through Hermosa and Andacollo faults, and it

presents an ascent of hydrothermal that strongly affects the Brecha Hermosa and

moderately toba. Later activation of structural systems is recorded, causing a strong

tectonism on the Brecha Hermosa. The late porphyry intrusion "El Culebrón" and andesitic

porphyry and finally a rise of late hydrothermal solution and the development of supergene

alteration.

The operation is an open pit mine and produces both porphyry copper cathodes (20.000

ton/year) and copper concentrate body of hypogene portion of the deposit (80.000

ton/year). The reserves of the supergene leacheable part of the deposit 7,247 Mt of 0.42 %

Cu, and the total mineral reserves of Carmen de Andacollo is 476,610 Mt of 0.35 % Cu

0.12 g/t Au (TECK-Carmen de Andacollo, 2012).

Fig 21: A); B) Carmen de Andacollo pit; C); D) Dust control by water sprayers trucks.

Fig 22: A) Group photo with the open pit behind; B) Group photo with sedimentation pool behind; C)

Beneficiation plant.

6. ACKNOWLEDGEMENTS

The field trip was possible because the support of academic organizations as the Society

of Economic Geologist SEG (http://www.segweb.org/) through the Funding Program, Data

Metallogenica DM (http://www.dmgeode.com/) through AMIRA P1040 project,

Corpogemmas (Corporación para el avance de la geología, geotécnia y minería en

armonía con el medio ambiente y la sociedad; Corporation for the advances of geology,

geotechnics and mining in armony with environmental and society -

http://www.corpogemmas.com/), Sociedad Colombiana de Geología SCG

(http://www.sociedadcolombianadegeologia.org/) and some national mining industries of

medium scale.

‘The information contained in the report is for information purposes only. The information

contained within the report may be changed or updated from time to time without notice.

The authors of this report have taken all reasonable care in producing and publishing

information contained in this report. Material in this report may contain technical or other

inaccuracies, omissions, or typographical errors, for which the Society of Economic

Geology assumes no responsibility. In consideration for using this material, the reader

agrees to hold the Society and its affiliates harmless against any claims for damages or

costs or any loss of any kind arising out of the access to or use of this report or any

information contained in or obtained through this report. Technical information contained in

this report is for personal use only. Any reliance on the information contained in these

reports by any third party shall be entirely at their own risk.’

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