In the western Cordillera highlands of Southern Peru argentiferous mineralization occurrences have been known since the Spanish conquest time; several mines are still at work in the area: San Juan de Lucanas, Arcata, Orcopampa Cailloma. Argentiferous mineralization mostly related to veins hosted by mainly andesitic rocks that we correlate with the Tacaza volcanic group of lower middle Miocene age (20·14 m. y.). Geochimical datas of Tacaza rocks compared with the ones of other main volcanio units from the same area Sencca and Huaylillas acid volcanics and Barroso andesitic volcanics) show that: -There is no difference between the three volcanic groups respect to the mejor-elements chemistry. All of them are characteristic of calcoalcalio series with high potassium contents. Minor elements average contents for each volcanic group are similar to those published for rocks from similar geote...

Páginas 83-86.

Investigaciones científicas por oro en la vertiente altiplánica de la Cordillera Sur- oriental (área de Ananea-Ancocala) y en el piedmont amazónico (área de Quincemii-Mazuko) ponen en evidencia el papel primordial de la evolución geomorfológica en la génesis de los placeres auríferos tanto en. ambiente glacial como en condiciones fluvio-torrenciales. En el área de Ananea-Ancocala el oro detrítico se encuentra concentrado en los depósitos glaciales y fluvioglaciales cuaternarios derivados de los esquistos epimetamórficos de la Formación Ananea (Siluro-Devónico). En la vertiente amazónica, el oro detrítico empezó a concentrarse a partir del Mioceno en depósitos fluviotorrenciales del piedemonte. La génesis de los placeres ha sido aquí estrechamente controlada por la evolución del material detrítico durante su transporte de la Cordillera hacia el piedemonte. Las conce...

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.

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.

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 As a consequence, outdated information and concepts are generally still used in current assessments and syntheses, and updated data are needed.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.

[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).