Publications des scientifiques de l'IRD

Garcia M., Riquelme R., Farias M., Hérail Gérard, Charrier R. (2011). Late Miocene-Holocene canyon incision in the western Altiplano, northern Chile : tectonic or climatic forcing ?. Journal of the Geological Society, 168 (4), p. 1047-1060. ISSN 0016-7649.

Titre du document
Late Miocene-Holocene canyon incision in the western Altiplano, northern Chile : tectonic or climatic forcing ?
Année de publication
2011
Type de document
Article référencé dans le Web of Science WOS:000291636300019
Auteurs
Garcia M., Riquelme R., Farias M., Hérail Gérard, Charrier R.
Source
Journal of the Geological Society, 2011, 168 (4), p. 1047-1060 ISSN 0016-7649
Major fluvial incision (600-1000 m) affecting the Coastal Cordillera and Central Depression of northern Chile is analysed to evaluate supposed coeval uplift of the Altiplano and/or climatic changes in the Atacama Desert. The timing of the beginning of incision is constrained by the age of deposition of the Central Depression top. In the north (18-19 degrees S), this top corresponds to fluvial gravels accumulated between 11.9 +/- 0.6 Ma and 8.3 +/- 0.5 Ma, which are genetically related to semiarid climate and to an eastward poorly dissected parallel drainage network that developed between 15.0 +/- 0.6 and 11.2 +/- 0.6 Ma; thus, gravel deposition ended at 11.9-11.2 Ma. To the south (19-208S), the Central Depression top corresponds to c. 6 Ma alluvial deposits. Stratigraphically determined canyon ages and knickzone locations indicate that southward dissection began later and/or developed under a regime of lower erosion capacity owing to drier climate. Vertical incision rate evolution is compatible with eastward knickzone migration. Dissection required a considerable altitude difference between ancient and present-day river base levels, which was achieved predominantly by basin infill on an already partially elevated bedrock. Therefore subsequent incision would have been triggered by local semiarid climatic periods rather than by contemporaneous surface uplift. Exoreic canyons occur when climatic conditions in the catchments are arid-semiarid whereas endoreism is developed when these conditions in catchments are hyperarid.
Plan de classement
Géologie et formations superficielles [064]
Localisation
Fonds IRD [F B010053631]
Identifiant IRD
fdi:010053631
Contact
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