hermosilla & otros rev 1

7/28/2019 Hermosilla & Otros Rev 1

1/22

Relevant tools for

generating geologic

models at Division Andina

Juan Hermosilla B.

Patricio Cuadra C.

Gonzalo Rojas S.

Cutting relationships between

porphyry and tourmaline breccias,

Ro Blanco area

CODELCOA N D I N A


2/22

Introduction

The Ro Blanco-Los Bronces

copper-molybdenum district is

emplaced in the upper Miocene to

Pliocene porphyry copper belt ofCentral Andes


3/22

Geological Background

Edad Rgimen

Tectnico

Unidades Estratificadas Unidades Intrusivas plutnicas Prfidos y

brechas

Plioceno-Cuaternario

(4-0 Ma)

Relajacin post-

compresin

Morrenas, coluvios y aluvios

no consolidados

Mioceno Superior-

Plioceno Inferior (6-4

Ma)

Compresin Niveles piroclstcos

subareos de la Chimenea

Rioltica

Prfidos dacticos y

andesticos,

brechas de

turmalina y de polvo

de roca, Chimenea

Rioltica

Mioceno Medio a

Superior (14-8 Ma)

Compresin Fm. Farellones, miembro

piroclstico superior

Monzonita, cuarzo-monzonita,

Granodiorita Ro Blanco, tonalita,

diorita, Granodiorita Cascada

Prfidos

andesticos

Mioceno Inferior Alto-

Mioceno Medio

Compresin Fm. Farellones, miembro

lvico intermedio

Sienogranito de Biotita

Mioceno Infer ior Compresin Fm. Farel lones, miembro

piroclstico inferior (fuera del

rea de trabajo)

Granodioritas, dioritas

Eoceno Superior-

Mioceno Inferior

Extensin Fm. Abanico


4/22

The district, is the worlds largest copper

concentration, exceeding 29.000 Mt (at 0.2% cut-off)

Cooke et. al. 2005. Camus, 2002.Eoceno-Oligoceno Belt Mioceno-Plioceno Belt

110 MT Cu

4Mt Mo


5/22

Why Geological Model is important ?

To understand thedistribution of metal content

Provides knowledge about

geological controls to guidethe resources estimation

Development of conceptual

models for the exploration ofnew resources in the district

DDH-4237

DDH-949

DDH-942-A

Modelo Litologa 2006 Modelo Litologa 2008

DDH-4237

DDH-949

DDH-942-A


SondajeDDH4237200m. 2.0%CuT

SondajeDDH949170m. 2.15%CuTy 0.011%Mo

DDH-4237

DDH-949

DDH-942-A


SondajeDDH4237200m. 2.0%CuT

SondajeDDH949170m. 2.15%CuTy 0.011%Mo

DDH-4237

DDH-949

DDH-942-A


-

-

- -

-

-

- -

ae 3. . T

a e 9 9

. . T .

-

-

- -

ae 3. . T

a e 9 9

. . T .

-

-

- -

Modelo Litologa 2006

DDH-841


DDH-845

DDH-877

DDH-894

DDH-919

DDH-884

DDH-913

DDH-889

DDH-841


DDH-841


DDH-845

DDH-877

DDH-894

DDH-919

DDH-884

DDH-913

DDH-889

DDH-841

DDH-845

DDH-877

DDH-894

DDH-919

DDH-884

DDH-913

DDH-889

DDH-841


DDH-845

DDH-877

DDH-894

DDH-919

DDH-884

DDH-913

DDH-889

DDH-841


EMSA, 2010


6/22

2004: A major methodological change

in Andina Divisin

Sampling support changed from 10 m to 2 m

Continuous improvement in geological core logging

methodology

different events of intrusion/breccia andalteration/mineralisation of the deposit

Application ofQA/QC procedures throughout the

entire process

Systematic application ofpetrographical studies and

strategically oriented geocronological analysis.


7/22

Why Change the Geological core logging

methodology >>> KNOWLEDGE

State of Art logging methodologies

Geological processes understanding

Porphyry copper geological knowledge

Repeatability and auditability of data

Diverse experience of geologists

Lack of alteration and mineralization concepts

Team turnover

Strengths

Weakn

esses


8/22

Team turnover


9/22

Changes in Geological core logging methodology

PRE 2004 2004

1:500 SCALE1:100 SCALE

INTENSITIES (1-5)

Lithological logging, > 60

rock codes.

Simplification of rock codes

table (27). Detailed breccia and

porphyry recognition.

Generic logging of

alteration and ore

minerals, for each 10 m

intervals.

Oriented to a detailed

understanding of primary

alteration and/or mineralisationcontrols. Single minerals

logging.

Only sulphides relative

ratios.

Total volume, relative ratios

and occurrence of sulphides.

Veinlets not logged.Veinlet logging (El Salvador

scheme.

Total Sericite loggingIdentification of gray-green

sericite (SGV).


10/22

Changes in Geological core logging methodology

2006 CURRENT

1:100 SCALE

VOLUMETRIC (%)

1:200 SCALE

VOLUMETRIC (%)

Emphasis on the detailed

logging oflithological contacts,

breccias and porphyries units.

Oriented to changes in

parameters that control the

alteration and/or mineralisation.

Simplified logging of

porphyries..

Oriented to log the main

alteration/mineralisation events,

through mineral associations.

Logging of Alteration Zones

Alteration associations include

all forms of occurrence of

alteration minerals (selective,

penetrative, patches,

brecciation, halos, etc.).

Differentiates the occurrence

forms according to its impact on

sulphide distribution. Selective

are logged separately of

penetrative texture-destructive

minerals.

Sulphides occurrence logging by

type of ore.


11/22

Innovation in Methodology

>>> Standardization, control and care of geological

information


12/22

Innovative introduction to the

Core Logging System

Considers a period of training in geological core logging,

whose aim is to provide standardization of knowledge and

practices of geological mapping

Guided presentations on:

Regional and District Geology of the deposit

Geological model relevant reports

Methodologies of data Capture and Analysis

Mine Geology Relevant Background

Relevant Background on Geometallurgy

Relevant Background on Resources Estimation


13/22

Geological Core Logging:

Internal working procedures and digital systems

logging

Geological logging procedure of Diamond Drill cores

and Cutting samples

QA/QC applied to Core Logging

Petrocalcographic studies procedures

Representative Lithological Samples

Training on Digital Mapping System

Innovative introduction to the

Core Logging System


14/22

Innovation in Induction to the Core logging

Assignment and Objectives

Designed to establish a direct link between the geologists

dedicated to geological interpretation and data

acquisition team, establishing requirements for each of

the drill holes, according to the objectives of geological

modelling .

Activities :

Review section and plan interpretation

Determine experience and capacities of the geologist

Online check for information of interpreted sections

Comparing information between different geologists of the team


15/22

Innovation in Standardisation of Mapping

Intensive reviews of geologists in training ,according to

the experience degree, with the objective to strengthen

the methodology into the team. Eventually, the

replacement of the log which does not achieve the

required quality must be done.

Activities :

Online review at least during the first three months of work by a

mapping quality team Check of consistency of information

Duplicate mappings


16/22

Innovation in Control Section

Information from detailed core logging must be regularly

transferred to draft sections and/or plans to control the

consistency and reproducibility of the data between nearby

drilling holes.

Activities :

At least, rock types, alteration and ore mineral associations must be considered.


17/22

Nube DispersinLeyes CuTAnalticas/ Estimada

r2 = 0.6532; r= 0.8082,p = 00.0000; y = 0.1486+ 0.7527*x

0 .0 0 .5 1 .0 1 .5 2 .0 2 .5 3 .0 3 .5 4 .0 4 .5 5 .0 5 .5 6 .0

CuTEstimada(%)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

CuT

Analtica(%)

DiferenciaLeyesCuT Analtica/ Estimada

0 .0 0 .5 1 .0 1 .5 2 .0 2 .5 3 .0 3 .5 4 .0 4 .5 5 .0 5 .5 6 .0

CuT Analtica(%)

-1.00

-0.75

-0.50

-0.25

0.00

0.25

0.50

0.75

1.00

Dif.CuT(%)

Innovation in Statistical Analysis

Statistical analysis of data must be done systematically

allowing categorize the quality of the information

obtained to take prompt actions appropriate techniques

to ensure the success of the process of geological data

capture

Activities :

Comparison between grade visual estimation v/s chemical results in cases

of logs done without chemical analysis

Chequeo Litologa (Quick Log v/s 1:200 logged)


18/22

Special Studies

To support mineralogical concepts and identification

special studies must be done

Activities :

Microscopic detailed studies with emphasis on characterization of

alteration mineral associations, assemblages of sulphide, a detaileddescription of filling and haloes veinlets

XRD in clay minerals

Infrared Spectroscopy (PIMA) in hand samples

XRF,ICP-MS, lithogeochemical analysis

QemScan in sulphide and alteration mineral associations

Microprobe in sericite phyllosilicates

Fluid Inclusin in veins

Geochronological Anaysis


19/22

>>> Standardization, Control and Care of

geological information


20/22

>>> GEOLOGICAL MODELLING


21/22

GEOLOGICAL MODELLING / GENETIC KNOWLEDGEParagenesis Lithologic, Veins and Mineralization Events


22/22

>>> GEOLOGICAL MODELLING CPY-(BO-SSCU); TS>1.0%

DISTRIBUCION DE SULFUROS

PY>>CPY; TS>2.0%

PY>>CPY; TS>1.0%

PY>>CPY; TSCPY; TS>2.0%

CPY>PY; TSPY; TS>2.0%

CPY>>PY; TS>2.0%

CPY>BO; TS>1.5%

CPY>PY; TSBO; TS

hermosilla & otros rev 1

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