Soil-Landform interplays from the Highlands of the Eastern Andes Cordillera to the lowlands of the Peruvian Amazon

Angelo Isminio Lama D.; Ernesto Gonçalves Reynaud Schaefer C.; Ferreira do Amaral E.; Lopes D.D.V.; Rocha Francelino M.; Osório Senra E. · Catena (2024) · DOI: 10.1016/j.catena.2024.108248

Resumen

The tropical mountain environments of the Eastern Peruvian Andes are home to rich biodiversity, pedodiversity, important Amazon water sources, unique landscapes and contrasting parent materials, landforms and climates. Despite all these varying features, knowledge about the tropical Andean region is still incipient, especially on the topographic and geological controls on the soil distribution. We investigated the main soils along a typical lithosequence, from the high slopes of the Eastern Cordillera (Cusco) to the lowlands of the Amazonian Peneplain (Madre de Dios), following a altitudinal range from 4725 down to 240 m.a.s.L. Morphological, physical, chemical and mineralogical analyses were performed on 11 soil profiles selected along the gradient, in three physiographic environments: The Eastern Oriental Cordillera, The Subandean Belt and The Amazon Peneplain. Altitude and lithology were key factors influencing soil attributes. Soils on the highest, pre-weathered alluvial terraces, of the Amazon Peneplain showed the greatest degree of pedogenetic development. With increasing altitude morphogenesis overcame pedogenesis at the Mountain slopes of the Subandean Belt, and on fluvio-glacial valleys of the Eastern Cordillera. At the highest part of the Andean Cordillera, most pedons have high accumulations of organic carbon under cold climates. The mineralogy of the clay fraction of all pedons was dominated by kaolinite, quartz and illite, with a higher degree of alteration in soils from the Amazon Peneplain, combined with the occurrence of crystalline Fe oxyhydroxides (goethite), in strong contrast with the Subandean Belt and Eastern Cordillera, where 2:1 minerals occur. Pyrophyllite and lepidocrocite were detected in pedons originated from metamorphic rocks, and chlorite in association with kaolinite in metasediments from the fluvio-glacial valleys of the Eastern Cordillera.

Instituciones: Universidad Nacional Toribio Rodríguez de Mendoza de Amazonas