Geologic and geochronologic constraints on the metallogenic evolution of the Andes of southeastern Peru

• DOI: 10.2113/gsecongeo.85.7.1520
• Publication Date: 2009-04-03T17:35:40Z
• Authors: Alan H. Clark; Edward Farrar; Daniel J. Kontak; Robert J. Langridge; Mario J. Arenas F.; Lynne J. France; Sandra L. McBride; Priscilla L. Woodman; Hardolph A. Waste...; Hamish A. Sandeman; Douglas A. Archibald
• Keywords: Batholith; Geochronology; Metallogeny; Peralkaline rock; Continental arc; Red beds; Back-arc basin

The post-Paleozoic metallogenic evolution of southeastern Peru is clarified on the basis stratigraphic and lithologic settings majority known metallic ore deposits a regional program K-Ar 40 Ar- 39 Ar geochronology. This central Andean transect displays range mineralization types unparalleled in other regions country. Contrasting magmatic, tectonic, relationships are shown by calc-alkaline--shoshonitic Upper Triassic--Holocene Main Arc magmatic domain, underlying present Cordillera Occidental Altiplano, more restricted Triassic--Pliocene Inner domain Oriental, which incorporates great variety igneous suites exhibits correspondingly diverse metallogeny. Major economic occurred simultaneously two domains only during late Oligocene to early Miocene interval.The earliest significant W, Cu, Mo, Sn, Au hosted largely weakly peraluminous granites Triassic Lower Jurassic (190-225 Ma) Carabaya batholith Arc; magma genesis resulted from sediment anatexis along margin Permian ensialic Mitu rift. Renewed rifting Middle (ca. 170-180 this area was associated with emplacement volcano-plutonic Allinccapac Peralkaline Complex, syenitic plutons host minor Ag, Zr(-REE) vein systems. Mesozoic Arc, weak comparison that transects, comprises (145-165 Cu-Au veins (e.g., Rosa Maria), mid-Cretaceous 95-110 Cu (Santiago, Valparaiso) Fe (Morritos, Cerro Pelado) Ilo-Ite district. Restricted Cretaceous 80 Cu-Pb-Zn-Ag Crucero district interpreted as recording brief episode arc broadening or bifurcation.Large-scale porphyry Cu(-Mo, Ag) centers were emplaced interval 52.15 (Cuajone) 57.1 Ma (Toquepala) terminal stage subaerial volcanic succession Cretaceous-Paleogene Toquepala Group, had previously experienced Cu(-Pb-Ag-Au) at ca. (Challatita) 62 (Lluta district). Eocene event represents culmination Peruvian Coastal its extension northern Chile. In contrast, extremity upper Eocene-lower Chile occurs study area, Ataspaca Cu-Mo-Pb-Zn-Ag stockwork skarn (39-45 pale reflection coeval array giant copper farther south. Much south-eastern lacked magmatism immediately before after 40-Ma Incaic orogeny hence hiatus. resuscitated Santa Lucia 31 32 Ma; 28.5 + - 1 it abruptly broadened width 235 km. However, hydrothermal activity remained both scale distribution. moderate-sized Berenguela 27 Barbara (23.5 epithermal Ag calc-alkaline subvolcanic centers, latter case initial stages cordilleran uplift. Post-Oligocene also apparently sparse broadly contemporary Ag-Au-base metal south-central Peru, but Au-rich Manazo camp (19 Cacachara (6.5-7 Compuerta camps (7 Ma).The revived 28 29 Ma, broadening. Anatexis resulting shoshonitic basalt injection generated strongly monzogranite stocks spatially major, high-grade, lithophile base lode systems, including San Rafael (23-24 Palca 11 (24-25 Ma), now most productive hard-rock Sn W Western Hemisphere. widespread middle region failed produce polymetallic developed Bolivia time; small Jesica system (17.4 has been confirmed contain Sb Collpa: 12.3 size. uranium stockworks (6.8-8.0 rare element-enriched, rhyolitic Macusani Volcanics large high grade.Although sharing several features contiguous differs markedly areas country nature age mineralization. Thus, does not persist northwest, radical commonly abrupt changes we define distribution magmatism, mineralization, Tertiary unrepresented Peru. individual ascribed inferred occurrence marked deflection western boundary South American plate throughout orogeny.