Tasas de denudacion de largo tiempo en los Andes Centrales, Chile, estimadas a partir de un modelo digital de elevacion usando la funcion 'Top Hat' por cierre y la interpolacion ponderada por el inverso de la distancia: implicancias del clima Neogeno del Desierto de Atacama.Long-term denudation rates from the Central Andes (Chile) estimated from a Digital Elevation Model using the Black Top Hat function and Inverse Distance Weighting: implications for the Neogene climate of the Atacama Desert.
Long-term denudation rates from the Central Andes (Chile) estimated from a Digital Elevation Model using the Black Top Hat function and Inverse Distance Weighting: implications for the Neogene climate of the Atacama Desert
| dc.contributor | en-US | |
| dc.contributor | es-ES | |
| dc.creator | Riquelme, Rodrigo | |
| dc.creator | Darrozes, Jose | |
| dc.creator | Maire, Eric | |
| dc.creator | Herail, Gerard | |
| dc.creator | Soula, Jean Claude | |
| dc.date | 2010-06-21 | |
| dc.identifier | http://www.andeangeology.cl/index.php/revista1/article/view/V35n1-a05 | |
| dc.identifier | 10.5027/andgeoV35n1-a05 | |
| dc.description | Una metodologia para determinar tasas de denudacion de largo tiempo a partir de marcadores geomorfologicos obtenidos desde un Modelo Digital de Elevacion (MDE), ha sido comprobada considerando un estudio comparativo de dos cuencas vertientes de la precordillera de los Andes Centrales. Para ambas cuencas, la configuracion inicial de una superficie de pedimentacion afectada por incision, ha sido reconstruida usando dos metodos diferentes: la funcion 'Top Hat' por Cierre (THC) y la Interpolacion Ponderada por el Inverso de la Distancia (IPID). Cuando se observa tanto incision vertical como erosion de laderas, la IPID es mas apropiada para reconstruir las superficies de pedimentacion. Por el contrario, donde solo se observa incision vertical, la THC describe con mayor precision las superficies de pedimentacion, y es de mas facil implementation. En este trabajo, se calculo un volumen erosionado por medio de la sustraccion del MDE del marcador geomorfologico reconstruido, y se estimo su incertitud al considerar un Error Cuadratico Medio y un MDE representando una grilla de errores. Para los ultimos 10 Myr se obtuvo tasas de denudacion de largo tiempo de 7,33±1,6 m/Myr en la cuenca vertiente de San Andres y de 13,59±1,9 m/Myr en la cuenca vertiente de El Salado. Estas estimaciones son similares a otras estimaciones de tasas de denudacion de largo tiempo publicadas para el Desierto de Atacama. La comparacion con valores de tasas de denudacion de largo tiempo reportadas para un amplio rango de regimenes climaticos sugiere que estas estimaciones no pueden ser explicadas por las actuales tasas de precipitacion de la Precordillera. Sin embargo, podrian ser explicadas por tasas de precipitacion similares a aquellas actualmente imperantes 40 km al este, en la Puna. Esto sugiere que durante el lapso de tiempo concerniente a la evolucion geomorfologica del area de estudio, esta evolucion es dominada por el control orografico de las precipitaciones. La preservacion de superficies de pedimentacion y los bajos valores de las tasas de denudacion de largo tiempo determinadas en este estudio indican, por otra parte, que la Precordillera no fue afectada por precipitaciones y masas de aire humedas tropicales como las que actualmente se observan en el Altiplano durante los meses de verano.ABSTRACT:A methodology for determining long-term denudation rates from morphologic markers in a Digital Elevation Model (DEM) is checked by a comparative study of two drainage basins in the PrecordiUera of the Central Andes. In both cases the initial configuration of an incised pediment surface has been restored by using two different methods: the Black Top Hat (BTH) function and the Inverse Distance Weighting (IDW) interpolation. Where vertical incision and hillslope erosion are recorded, the IDW appears to be the most adequate to reconstitute the pediment surfaces. Conversely, where only vertical incision is observed, the BTH describes more precisely the former pediment surfaces and it is easier to solve. By subtracting the DEM from the reconstructed marker we calculated an eroded volume, and estimated its uncertainty by considering Root Mean Square Error (RMSE) and DEM grid error. For the last ~10 Myr we obtained long-term denudation rates of 7.33±1.6 m/Myr in the San Andres drainage basin and 13.59±1.9 m/Myr in the El Salado drainage basin. These estimations are largely in agreement with other reported estimates of long-term denudation rates in the Atacama Desert. Comparison with long-term denudation rates reported in a wide range of climatic regimes suggests that our estimates cannot be explained by the current rainfall in the PrecordiUera. However they could be explained by a rainfall similar to that reported 40 km to the east in the Puna. This suggests that during the time span concerned the geomorphologic evolution of the study area, this evolution is dominated by an orographically controlled rainfall pattern. The preserved pediment surface and the small long term denudation rates determined in this study also indicate that the PrecordiUera was never reached by humid tropical air masses and precipitation as currently observed in the Altiplano during the summer months. | es-ES |
| dc.description | A methodology for determining long-term denudation rates from morphologic markers in a Digital Elevation Model (DEM) is checked by a comparative study of two drainage basins in the PrecordiUera of the Central Andes. In both cases the initial configuration of an incised pediment surface has been restored by using two different methods: the Black Top Hat (BTH) function and the Inverse Distance Weighting (IDW) interpolation. Where vertical incision and hillslope erosion are recorded, the IDW appears to be the most adequate to reconstitute the pediment surfaces. Conversely, where only vertical incision is observed, the BTH describes more precisely the former pediment surfaces and it is easier to solve. By subtracting the DEM from the reconstructed marker we calculated an eroded volume, and estimated its uncertainty by considering Root Mean Square Error (RMSE) and DEM grid error. For the last ~10 Myr we obtained long-term denudation rates of 7.33±1.6 m/Myr in the San Andrés drainage basin and 13.59±1.9 m/Myr in the El Salado drainage basin. These estimations are largely in agreement with other reported estimates of long-term denudation rates in the Atacama Desert. Comparison with long-term denudation rates reported in a wide range of climatic regimes suggests that our estimates cannot be explained by the current rainfall in the PrecordiUera. However they could be explained by a rainfall similar to that reported 40 km to the east in the Puna. This suggests that during the time span concerned the geomorphologic evolution of the study area, this evolution is dominated by an orographically controlled rainfall pattern. The preserved pediment surface and the small long term denudation rates determined in this study also indicate that the PrecordiUera was never reached by humid tropical air masses and precipitation as currently observed in the Altiplano during the summer months. | en-US |
| dc.format | application/pdf | |
| dc.format | text/html | |
| dc.language | eng | |
| dc.publisher | Servicio Nacional de Geología y Minería | en-US |
| dc.relation | http://www.andeangeology.cl/index.php/revista1/article/view/V35n1-a05/407 | |
| dc.relation | http://www.andeangeology.cl/index.php/revista1/article/view/V35n1-a05/html | |
| dc.source | Andean Geology; Vol 35, No 1 (2008) | es-ES |
| dc.source | Andean Geology; Vol 35, No 1 (2008) | en-US |
| dc.source | 0718-7106 | |
| dc.source | 0718-7092 | |
| dc.title | Tasas de denudacion de largo tiempo en los Andes Centrales, Chile, estimadas a partir de un modelo digital de elevacion usando la funcion 'Top Hat' por cierre y la interpolacion ponderada por el inverso de la distancia: implicancias del clima Neogeno del Desierto de Atacama.Long-term denudation rates from the Central Andes (Chile) estimated from a Digital Elevation Model using the Black Top Hat function and Inverse Distance Weighting: implications for the Neogene climate of the Atacama Desert. | es-ES |
| dc.title | Long-term denudation rates from the Central Andes (Chile) estimated from a Digital Elevation Model using the Black Top Hat function and Inverse Distance Weighting: implications for the Neogene climate of the Atacama Desert | en-US |
| dc.type | info:eu-repo/semantics/article | |
| dc.type | info:eu-repo/semantics/publishedVersion | |
| dc.type | es-ES | |
| dc.type | en-US |
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Andean Geology
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