Páginas 191-195.

La región de Puno cubre partes del Altiplano peruano y de la Cordillera Occidental, y presenta una estratigrafía original, así como una distribución de unidades estrechamente controlada por la estructura tectónica regional.

Integration of the zircon U-Pb ages available on the Toquepala Group, La Caldera batholith (s.l.), and porphyry Cu systems, in combination with geochemical data, unravels the evolution of the magmatic arc of southernmost Peru during the Late Cretaceous and Early Paleogene. Arc magmatic production increased starting ~90 Ma, and culminated between ~74 and ~62 Ma through a flare-up characterized by large plutonic and volcanic (especially ignimbritic) volumes. This long process resulted in the thickening of the arc crust, to a state of overthickening that triggered its extensional collapse, starting diachronously 61–59 Ma, during which giant porphyry Cu systems were emplaced between ~60 and ~53 Ma. Our empirical reconstruction of this protracted evolution provides simple guides for exploration of giant porphyry Cu deposits in southern Peru, as well as a magmatotectonic theoretical framewor...

Although Andean southern Peru forms the northwestern termination of the Bolivian Orocline, knowledge of its geology has little progressed in the last 20 years, partly due to the civil war that spread in the region during the 1980s and early 1990s. As a consequence, outdated information and concepts are generally still used in current assessments and syntheses, and updated data are needed. This short descriptive contribution presents the principal tectonic elements we currently recognize in southern Peru, and their relationships with syntectonic sedimentary basins. We observe that the most prominent deformational systems in this part of the Bolivian Orocline are dominantly transcurrent, and that many magmatic manifestations are associated with them.

Damos a conocer edades inéditas obtenidas por los métodos 40Ar-39Ar y K-Ar sobre rocas volcánicas y plutónicas del sur del Perú, y las comentamos brevemente.

[ENG] Three large transcurrent systems, with related magmatism, are identified in southern Peru. A ∼40-80km-wide, N150-trending, dextral corridor (CECLLA =Cusco-Lagunillas-Laraqueri-Abaroa structural corridor) is characterized by thick Oligocene basic lavas and numerous intrusions. The other two systems are oriented ∼N125-130 and sinistral, and cartographically related to the CECLLA. Miocene to Quaternary basic magmas are associated to the northeastern system (SFUACC = Urcos-Ayaviri-Copacabana-Coniri fault system). In the southwestern region, the abundant Late Cretaceous-Paleocene arc magmatism seems related to the Incapuquio-El Castillo fault system (SFIEC).

4 páginas

[EN] Improving the chances of success of mineral exploration requires to interconnect metallogenetic analyses with the geological evolution of western Peru that can be reconstructed from current knowledge and ongoing investigations. This communication presents a preliminary stage in this research.

Los afloramientos del Jurásico- Cretácico inferior en el borde oriental de la cuenca de Arequipa conforman 4 sectores, que se agrupan en las áreas de Mañazo-Lagunillas y de Río Blanco-Loripongo-Yunga. En ambas zonas no aflora el contacto inferior con otras unidades más antiguas.

La Formación Ayabacas (~Turoniano) es una unidad resedimentada que se observa sobre un área superior a 50000 km2 en el Altiplano y la Cordillera Oriental del sur del Perú (Sempere et al., 2000). Su génesis fue explicada de maneras muy diferentes: fallamiento de bloques y erosión intensa (Heim, 1947), tectónica con pliegues y cabalgamientos (Newell, 1949; Chanove et al., 1969), deformación disarmónica y/o polifásica, fracturación causada por karstificación y/o diapirismo de yesos, intrusiones hipovolcánicas (Audebaud, 1971), caos producido por deslizamientos subaéreos (De Jong, 1974) o submarinos (Audebaud, 1967; Sempere et al., 2000). El estudio en curso soporta esta última interpretación, describiendo la Fm Ayabacas como una megabrecha (u olistostromo), es decir el resultado de deslizamientos submarinos de gran amplitud (Spence and Tucker, 1997). Aunque las interpretacion...

The Chocolate Formation is exposed in southern Peru between the cities of Nazca and Tacna, mostly in the Pacifie slopes of the Cordillera Occidental and along the coast. This lithostratigraphic unit was initially described near Arequipa by Jenk s (1948; "Volcànicos Chocolate"), who assigned a Jurassic age to it. It consists of a succession of volcanic rock s, sandstones, and con glomerates. Near the top of the unit, a Sinemurian ammonite was found in a fossiliferous limestone intercalation. In Tacna a similar unit was mapped as "Junera ta Formation" by Wilson & Gard a (1962) and later equated with the Chocolate Formation (Monge & Cerv antes, 2000). Recent studies have suggested that the base of this unit might be as old as Late Carboniferous (Pino et a l., 2004; Sempere et al., 2004). Because the Chocolate volcanism is likely to have been active in the middle Permian, it partly represen...

4 páginas

Fault systems observed in the southernmost Peruvian forearc (Tacna area) provide information on the structure of the inner Bolivian Orocline (Arica elbow). Here we present the characteristics of the main fault systems observed in the Tacna area, as well as evidences of structural control on the deposition of Upper Cenozoic units and regional geoforms. We propose a synthetic chronology of deformation.

The Bolivian tin belt is a metallogenic province in the Eastern Cordillera of the Andes known for its Sn, W, Ag, and base metal deposits. Cassiterite, which is a major constituent in many magmatic-hydrothermal ore deposits from the Bolivian tin belt, can incorporate dozens of elements within its crystal lattice, making it a useful geological tracer mineral and also a potential host of critical elements. New U-Pb dating of cassiterite yields Late Triassic (Kellhuani deposit) and Late Oligocene to earliest Miocene (Viloco, Huanuni, and Llallagua deposits) ages. These ages confirm that Sn mineralization in the Bolivian tin belt occurred at least in two separate events during two major magmatic episodes apparently triggered by mantle upwelling, decompression melting, and basalt production promoting high heat flow into the overlying crust. The composition of studied hydrothermal cassiterite y...

21 p.

Páginas 817-820.

El Instituto Geológico Minero y Metalúrgico (Ingemmet), ente rector de la geología en el Perú encargado de realizar y fomentar la investigación de los recursos minerales a través de la Dirección de Recursos Minerales y Energéticos, ha elaborado el Compendio minería y yacimientos minerales del Perú. Este trabajo surge de la necesidad de promover la historia minera en el Perú, difundir los principales yacimientos mineros en el siglo XXI y resaltar la importancia de la minería en la evolución y desarrollo de nuestra sociedad. Brinda información de los yacimientos minerales del Perú con información y descripción de sus principales rasgos geológicos, metalogenéticos, controles estructurales, las principales guías de mineralización e información histórica minera de los yacimientos peruanos y su incidencia en el desarrollo económico nacional. El Compendio minería y yaci...