3. Geology of Ore Deposit

7/24/2019 3. Geology of Ore Deposit

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Metallogenic ProvincesMetallogenic Provinces

Geology of Ore Deposits:Geology of Ore Deposits:An OverviewAn Overview

ByBy

DR. ARIFUDIN IDRUSDR. ARIFUDIN IDRUS

Laboratory of Mineral ResourcesLaboratory of Mineral ResourcesDepartment of Geological EngineeringDepartment of Geological Engineering

Gadjah Mada UniversityGadjah Mada University

Jl. Grafika No. 2Jl. Grafika No. 2 BulaksumurBulaksumurYogyakarta 55281 IndonesiYogyakarta 55281 Indonesiaa


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Major tectonic plates

Lempeng Pasifik

Lempeng AfrikaLempeng Hindia-Australia

Lempeng Antartik

Lempeng Eurasia

Lempeng Amerika Utara

LempengAmerika Selatan

Lempeng Nazca


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Tectonic setting vs Ore depositsTectonic setting vs Ore deposits


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SSouthwest Pacific Rimouthwest Pacific Rim


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Tertiary island arcs in IndonesiaTertiary island arcs in Indonesia


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CommodityCommodity--type classification of ore deposittype classification of ore deposit(Evans, 1993):(Evans, 1993):

Precious metals (logam mulia)Precious metals (logam mulia): emas (Au), perak (Ag), platina (Pt): emas (Au), perak (Ag), platina (Pt)

NonNon--ferrous metals (logam nonferrous metals (logam non--ferrous)ferrous): tembaga (Cu), timbal: tembaga (Cu), timbal(Pb/lead), seng (Zn/zinc), timah (Sn/tin), dan aluminium (Al). E(Pb/lead), seng (Zn/zinc), timah (Sn/tin), dan aluminium (Al). Empatmpatpertama dikenal sebagai logam dasar (base metals).pertama dikenal sebagai logam dasar (base metals).

Iron and ferroalloy metals (logam ferroalloy dan besi)Iron and ferroalloy metals (logam ferroalloy dan besi): besi (Fe),: besi (Fe),Mangan (Mn), nikel (Ni), krom (Cr), molibdenum (Mo), wolframMangan (Mn), nikel (Ni), krom (Cr), molibdenum (Mo), wolfram

(W/tungsten), vanadium (V), kobal (Co).(W/tungsten), vanadium (V), kobal (Co). Minor metals and related nonMinor metals and related non--metalsmetals : antimon (Sb/antimony),: antimon (Sb/antimony),

arsen (As), berilium (Be/beryllium), bismut (Bi), kadmium (Cd),arsen (As), berilium (Be/beryllium), bismut (Bi), kadmium (Cd),magnesium (Mg), air raksa (Hg/mercury), REE, selenium (Se),magnesium (Mg), air raksa (Hg/mercury), REE, selenium (Se),

tantalium (Ta), telurium (Te), titanium (Ti), Zirkonium (Zr), dstantalium (Ta), telurium (Te), titanium (Ti), Zirkonium (Zr), dsb.b.

Fissionable metalsFissionable metals : uranium (U), torium (Th), radium (Ra).: uranium (U), torium (Th), radium (Ra).


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Genetic classification of Ore depositsGenetic classification of Ore deposits

MMagmatiagmaticc--hhydrothermalydrothermal--related depositsrelated deposits Magmatic lMagmatic l iquidiquid deposits: Cr, Ni, PGMdeposits: Cr, Ni, PGM

PegmatitPegmatitee (Sn, Nb/Ta, Li, Be, etc).(Sn, Nb/Ta, Li, Be, etc).

HyHydrotdrothhermal:ermal: CyprusCyprus--typetype (VMS); skarn (W, Sn, Cu, etc), por(VMS); skarn (W, Sn, Cu, etc), porphyryphyry (Cu,(Cu,Mo, Sn, etc);Mo, Sn, etc); Vein/lodeVein/lode (Sn, W, U);(Sn, W, U); EEpitpithhermalermal ((AuAu--AgAg))..

HyHydrotdrothhermalermal--diagenetidiagenetic related depositsc related deposits KupferschieferKupferschieferttypesypes (Cu, Pb, Zn)(Cu, Pb, Zn) SEDEXSEDEX

MississippiMississippi--Valley TypeValley Type (MVT): Pb(MVT): Pb--ZnZn--BaBa--FF in marine carbonatesin marine carbonates

HyHydrotdrothhermalermal--metamormetamorphic related depositsphic related deposits QuartzQuartz--lode gold (orogenic gold deposits)lode gold (orogenic gold deposits)

Chemical weathering related depositsChemical weathering related deposits Bauxite,Bauxite, FeFe--lateritlaterite,e, NiNickel andckel andAu lateritAu lateriteses

Mechanical weathering related depositsMechanical weathering related deposits Placer deposits (alluvial, marine): Au, Sn, Fe/Ti, REE)Placer deposits (alluvial, marine): Au, Sn, Fe/Ti, REE)


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Geology of Bushveld complex, RSAGeology of Bushveld complex, RSA


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Chromite layers of Bushveld complexChromite layers of Bushveld complex


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Model ofModel of AuAu--AgAg low sulphidationlow sulphidation epitermalepitermal depositdeposit

Epithermal refers to mineral deposits that form in association with hot waters.

The deposits form within 1 km of the surface and water temperatures are about

50-200 degrees C.


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CLASSIC MODEL OF PORPHYRY DEPOSITSCLASSIC MODEL OF PORPHYRY DEPOSITS

PERIPHERAL

Ccp-Gn-Sp-Au-Ag PERIPHERAL

Ccp-Gn-Sp-Au-Ag

LOW PYRITE

SHELL

Py ~2%

Mag>Py

PYRITESHELLPy~10%Ccp0.1-3%Morare

Mag>Py& Ccp

ORE SHELLPy 1%Ccp 1-3%Mo 0.03%

LOW GRADE

CORE

low totalCcp-Py-Mo

?

?

SAN MANUEL FAULT

KALAMAZOOSEGMENT

SAN MANUELSEGMENT

Propylitic(Chl-Ep-Carb)

Adul-Ab

Argi ll icQtz-Kln-Chl

PhyllicQtz-Ser-Py

PotassicQtz-Kfs-Bt-+Ser+Anh

Qtz-Ser-Chl-Kfs

Chl-Ser-Ep-Mag

?

?

?

??

A


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Three major models:

1. Quartz-monzonite

2. Diorite

3. Breccia

QuartzQuartz--MonzoniteMonzonite

modelmodel


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Quartz lode goldQuartz lode gold


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Schematic illustrations showing the principal features of Archean erogenic gold deposits -

many of which also apply to Proterozoic and Phanerozoic examples. The main features at amegascale are that the deposits are associated with a convergent plate margin where

metamorphism results in the production of fluids that are focused along major structural

discontinuities. At a mesoscale major shear zones within or along the margins of greenstone

belts represent district-scale hosts to mineralization that are accompanied by broad zones of

intense alteration. Individual deposits occur along second- and third-order structures. Oredeposition is a function of fluid rock reaction and/or H2O-CO2 phase separation (after

Hagemann and Cassidy, 2000).


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Quartz lode goldQuartz lode gold


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Volcanogenic Massive SulphideVolcanogenic Massive Sulphide

VMS d i d l (K k )VMS d i d l (K k )


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VMS deposit model (Kuroko type)VMS deposit model (Kuroko type)

Maj or sour ce of BMaj or sour ce of Base met al s, e.g. Cu, Zn dan Pbase met al s, e.g. Cu, Zn dan Pb


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Diagram illustrating the setting for the formation of SEDEX-type Pb-Zn ores and a scenario

which incorporates both exhalative and replacement concepts for the formation of theseores (after compilations by Goodfellow et al., 1993; Misra, 2000).


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SEDEX (e.g. Sullivan, Canada)


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SEDEX Deposits

Sulphide mineral layers are enclosed by and parallel to thesedimentary strata.


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Placer DepositsPlacer Deposits

Placer deposit : formed by the mechanical concentrationPlacer deposit : formed by the mechanical concentrationof resistant mineralsof resistant minerals, which, which are released by weatheringare released by weathering

from source rocksfrom source rocks

Main Commodities:Main Commodities:Tin, Gold, Platinum, Niobium, Tantalum, Titanium, Zircon,Tin, Gold, Platinum, Niobium, Tantalum, Titanium, Zircon,

DiamondDiamond

PaleoPaleo--placers:placers:The lithified equivalents of placer depositThe lithified equivalents of placer deposit

Economic deposits are limited geographical distributionEconomic deposits are limited geographical distribution

(Archean(ArcheanProterozoic)Proterozoic) Uranium, CanadaUranium, Canada

Gold & Uranium, South AfricaGold & Uranium, South Africa

TinTinbearing paleobearing paleo--placer: Nigeria, Brazil, Malaysiaplacer: Nigeria, Brazil, Malaysia

Gold placer depositGold placer deposit


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Gold placer depositGold placer deposit

Ni k l l t it d it: P f i l


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Nickel laterite deposit: Prof i le

Nickel laterite deposit: Soroako


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Nickel laterite deposit: Soroako

Nickel laterite deposit: Hand Auger drilling


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Nickel laterite deposit: Hand Auger drilling

Nickel laterite deposit: Cor e loggi ng


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Nickel laterite deposit: Cor e loggi ng

Nickel laterite deposit: Deposi t model l i ng


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Nickel laterite deposit: Deposi t model l i ng

Nickel laterite deposit: Min ing /exp lo i ta t ion


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3. Geology of Ore Deposit