Ore Petrography and Metal Zonation of the World-Class Cerro Lindo Volcanic-Hosted Massive Sulfide Deposit, Perú
2019 (engelsk)Independent thesis Advanced level (degree of Master (Two Years)), 80 poäng / 120 hp
Oppgave
Abstract [en]
The Cerro Lindo volcanic-hosted massive sulfide deposit is located in Chavin district of Chincha Province in southwestern Peru, circa 240 km south of Lima. With past production of 39.9 MT, and current resource estimate of 87.4 Mt, the deposit totals 127.3 Mt ore, grading 2.6% Zn, 0.30% Pb, 0.79% Cu, and 25.5g/t Ag. The Cerro Lindo deposit thus represents one of the largest deposits of its kind. However, few comprehensive studies to constrain the deposit characteristics have been conducted so far. This contribution focuses on the ore bodies and includes 3D modeling of metal distribution, petrographic analysis on ore samples, and laser ablation-inductively coupled plasma-mass spectrometry on sphalerite, the main ore mineral. The massive sulfide lenses of the Cerro Lindo deposit are hosted by the Albian-Cenomanian Huaranguillo Formation of the Casma Group, which forms a belt of submarine volcanic rocks extending for over 1,600 km along the coast of Peru from Piura in the north to Ica in the south. The deposit consists of eight NW-SE trending ore lenses formed within a felsic volcanic succession dominated by coherent rhyolite and associated breccias. The deposit and its host rocks form a roof pendant within the younger Coastal Batholith and have experienced contact metamorphism. Optical microscopy and automated mineralogy imaging conducted on a scanning electron microscope demonstrate that much of the ore has been recrystallized. Static recrystallization textures are characteristic for minerals such as barite and pyrite, with contacts between grains forming triple junctions that have interfacial angles of ~120°. The study of the ore at Cerro Lindo provides a unique opportunity to constrain the effects of metamorphism on massive sulfide ores, which likely resulted in an increase in the economic value of the deposit due to coarsening of the grains reducing milling costs
sted, utgiver, år, opplag, sider
2019.
HSV kategori
Identifikatorer
URN: urn:nbn:se:ltu:diva-73895OAI: oai:DiVA.org:ltu-73895DiVA, id: diva2:1314770
Eksternt samarbeid
Colorado School of Mines; Companera Minera Milpo (Votorantim)
Fag / kurs
Student thesis, at least 30 credits
Utdanningsprogram
Geosciences, master's level (120 credits)
Veileder
Examiner
2019-09-102019-05-092019-09-10bibliografisk kontrollert