Maden Yatakları Skarnlaşma Nasıl Olur - İngilizce içerik - 1 60 T ürkiye Jeoloji Kurultayi Exploration for Skarn Deposits Larry Meinert Department of Geology Smith College Northampton, MA 01063 USA Email: Lmeinert@smith.eduSkarns 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 JayaDepth of Formation - W Skarns • Tonnage and grade 63 Mt of 0.95 WO3 • Igneous Composition calc-alkaline granodiorite to granite • Igneous geometry c.g. batholith with pegmatite, megacrysts • Igneous alteration Fresh, minor myrmekite, Ca endoskarn • Metamorphism Extensive metamorphic aureole (km) with high T mineral assemblages and reaction skarns (bimetasomatism)Pine Creek, CA W skarn Granodiorite Skarn MarbleSub-calcic garnet Calcic garnet & pyroxeneScheelite Sub-calcic garnet veinsDepth of Formation - Cu Skarns • Tonnage and grade 500 Mt of 0.8% Cu • Igneous Composition calc-alkaline diorite to quartz monzonite • Igneous geometry m.g. to porphyritic stocks and dikes • Igneous alteration K-silicate, sericitic, epidote endoskarn • Metamorphism Variable metamorphic aureole (cm to km) lacks high T mineral assemblagesDistal Features - Zn Skarns • Tonnage and grade 50 Mt of 10% Zn, 5% Pb, 150 g/t Ag • Igneous Composition granodiorite to granite to unknown • Igneous geometry batholith to stocks to dikes to unknown • Igneous alteration Extensive epidote±garnet endoskarn • Metamorphism Bleaching and recrystallization, no high T metamorphic aureoleSkarns 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 JayaSkarns 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 JayaSkarn deposits of PeruAntamina Cu-Zn skarn, Peru 1) > 1 billion tons of Cu-Zn resource 2) ~ Barren porphyry intrusive center 3) Abundant endoskarn 4) Classic skarn zonationQuartz monzonite porphyryEndoskarn PorphyryGreen garnet skarnGarnet PyroxeneGarnet WollastoniteMarble Garnet skarnCalcite ± wollastonite veining Gray marbleFluid escape structures MarbleWhat if Turkey had as many ore deposits as Peru?Turkey ore deposit density by analogy with PeruErtsberg 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