Examinando por Autor "Toro, G."
Mostrando 1 - 5 de 5
Resultados por página
Opciones de ordenación
Ítem Fission-track datings and geomorphic evidences for long-term stability in the Central Cordillera highlands, Colombia(Gebruder Borntraeger Verlagsbuchhandlung, 2006-01-01) Toro, G.; Hermelin, M.; Schwabe, E.; Posada, B.O.; Silva, D.; Poupeau, G.; Toro, G.; Hermelin, M.; Schwabe, E.; Posada, B.O.; Silva, D.; Poupeau, G.; Universidad EAFIT. Departamento de Ciencias; Geología Ambiental y TectónicaAge of weathered andesitic volcanic ash layers, which cover most of the landscape in the Central Cordillera northern massif plateaus in Colombia, were determined through the use of fission track counting in volcanic zircon crystals. A stoneline, exposed in many outcrops, which corresponds to the lower limit of younger tephras, gave ages between 350 ka and 440 ka. Andosols lying above the stoneline could not be dated. Paleolake deposits in the study area and surroundings were dated at about 2 Ma; older ashes deposited on the Rio Negro erosion surface (SII) below the stoneline level gave ages between 3.4 and 5.4 Ma. The study area is located about 150 km from the volcanic center. The ash layers decrease in thickness only slightly with distance, as perceived from profiles sampled in flat areas. We conclude that the only noticeable erosional event in the region was the emplacement of the stone-line. This erosion event which was relatively short and mild in intensity, as part of the underlying soil derived from quartzdiorite was preserved. This soil formed above a saprolite with a thickness which may reach 150 m, a fact which supports the inference that the plateaus have been stable for millions of years, in contrast to the high erosion rates observed in the surrounding steep slopes and canyons. © 2006 Gebrüder Borntraeger.Ítem Geomorphological characteristics of the ruiz volcano and surroundings(Springer International Publishing, 2015-01-01) Hermelin, M.; Toro, G.; Mendez, R; Tavera, Miguel AngelLandforms related to the Ruiz Volcano, the northernmost active volcano in South America, are both of volcanic and glacial origins. A brief historical account includes several eruptions and culminates with the catastrophic one which occurred in November 13th, 1985. A description of the geological evolution of the area is complemented by an itinerary which will permit the observation of the more important landforms. © Springer International Publishing Switzerland 2016. All rights reserved.Ítem large magnitude late holocene seismic activity in the Pereira - Armenia region, Colombia(The Geological Society of America, 2011-01-01) Lalinde, Claudia Patricia; Toro, G.; Velásquez, A. A.; Audermad, Franck A.The Pereira-Armenia region, located west of the Colombian Central Cordillera, is crosscut by the Romeral fault system, which consists of an active north-south?trending, left-lateral, strike-slip fault system with a secondary thrust componentÍtem large magnitude late holocene seismic activity in the Pereira - Armenia region, Colombia(The Geological Society of America, 2011-01-01) Lalinde, Claudia Patricia; Toro, G.; Velásquez, A. A.; Audermad, Franck A.The Pereira-Armenia region, located west of the Colombian Central Cordillera, is crosscut by the Romeral fault system, which consists of an active north-south?trending, left-lateral, strike-slip fault system with a secondary thrust componentÍtem The guamuéz (La Cocha) lake(Springer International Publishing, 2015-01-01) Duque-Trujillo J.F.; Hermelin, M.; Toro, G.