60 T ü rkiye Jeoloji Kurultayi Exploration for Skarn Deposits Larry Meinert Department of Geology Smith College Northampton, MA USA

Skarns and Skarn Deposits 1)General processes of skarn formation 2)Mineralogy, petrology, & tectonic setting 3) Examples of major skarn deposits: Antamina - Peru Ertsberg District - Irian Jaya

Depth of Formation - W Skarns Tonnage and grade63 Mt of 0.95 WO3 Igneous Compositioncalc-alkaline granodiorite to granite Igneous geometryc.g. batholith with pegmatite, megacrysts Igneous alterationFresh, minor myrmekite, Ca endoskarn MetamorphismExtensive metamorphic aureole (km) with high T mineral assemblages and reaction skarns (bimetasomatism)

Pine Creek, CA W skarn Granodiorite Skarn Marble

Sub-calcic garnet Calcic garnet & pyroxene

Scheelite Sub-calcic garnet veins

Depth of Formation - Cu Skarns Tonnage and grade500 Mt of 0.8% Cu Igneous Compositioncalc-alkaline diorite to quartz monzonite Igneous geometrym.g. to porphyritic stocks and dikes Igneous alterationK-silicate, sericitic, epidote endoskarn MetamorphismVariable metamorphic aureole (cm to km) lacks high T mineral assemblages

Distal Features - Zn Skarns Tonnage and grade50 Mt of 10% Zn, 5% Pb, 150 g/t Ag Igneous Compositiongranodiorite to granite to unknown Igneous geometrybatholith to stocks to dikes to unknown Igneous alterationExtensive epidote±garnet endoskarn MetamorphismBleaching and recrystallization, no high T metamorphic aureole

Skarns and Skarn Deposits 1)General processes of skarn formation 2)Mineralogy, petrology, & tectonic setting 3) Examples of major skarn deposits: Antamina - Peru Ertsberg District - Irian Jaya

Skarns and Skarn Deposits 1)General processes of skarn formation 2)Mineralogy, petrology, & tectonic setting 3) Examples of major skarn deposits: Antamina - Peru Ertsberg District - Irian Jaya

Skarn deposits of Peru

Antamina Cu-Zn skarn, Peru 1)> 1 billion tons of Cu-Zn resource 2)~ Barren porphyry intrusive center 3) Abundant endoskarn 4) Classic skarn zonation

Quartz monzonite porphyry

Endoskarn Porphyry

Green garnet skarn

Garnet Pyroxene

Garnet Wollastonite

Marble Garnet skarn

Calcite ± wollastonite veining Gray marble

Fluid escape structures Marble

What if Turkey had as many ore deposits as Peru?

Turkey ore deposit density by analogy with Peru

Ertsberg Cu-Au district, Irian Jaya 1)> 2 billion tons of Cu-Au reserves, largest Cu-Au resource on Earth 2)~ Mineralized porphyry intrusive centers 3) No endoskarn 4) Classic skarn zonation

Tembagapura mine camp housing for ~ 7,000 workers

Tram car carries workers at a time up to mine site

Mine site at 4,000 m Usually is in clouds

Tram station at mine site, looking down to mill site in valley

Tram station Original Ertsberg ore body

Tram station

Tram station

Yellow Valley syncline Puncak Jaya 5000 m

Grasberg pit

Marble Diorite Endoskarn

Mt-cp-bn

Mg skarn with olivine, monticellite, vesuvianite

Mg skarn with retrograde serpentine veins

Biotite hornfels Garnet veinPyroxene envelope/vein

Red-brown garnetAnhydrite Cp

Red-brown garnetPyroxene

Pyroxene-chalcopyrite skarn

Distal diopsidic pyroxeneAnhydriteLate Fe-rich pyroxene

Fluid escape structures in marble

GarP>GPyxMarble Fluid escape structures