Abstract

FLOREZ-MOLINA, María Teresa; PARRA-SANCHEZ, Luis Norberto; JARAMILLO-JARAMILLO, Daniel Francisco  and  JARAMILLO-MEJIA, José María. Macromorphological and micromorphological evidence of the paleosols of La Tatacoa desert and its synchronic variation. Rev. acad. colomb. cienc. exact. fis. nat. [online]. 2018, vol.42, n.165, pp.422-438. ISSN 0370-3908.  https://doi.org/10.18257/raccefyn.702.

We studied the red layer assemblages of La Tatacoa desert in Huila, Colombia, in order to verify the presence of paleosols and to establish their properties and spatial variability, as well as the environmental conditions under which they were formed. We found alkaline paleosols in the lower red layers and in the ferruginous ones that had the following characteristics: illuvial horizons Bt of red color, with a structure in angular blocks, low content of organic matter, cutans and slickensides that showed translocation of iron and manganese oxides and calcium carbonates. In addition, there was a strong spatial variability in the thickness and the position of the paleosols with respect to the lithic beds. The pedogenetic processes responsible for the evolution of the paleosols were clay illuviation and lessivage, mineralization of organic matter, solodization, flushing, fersialitization, carbonation, aeration, and water erosion. These processes indicate that the pedogenesis occurred in a seasonal climate contrasted in humidity with a very dry season followed by another very rainy one. The presence of paleosols interspersed with lithic layers of variable granulometry without pedogenesis imply that there was significant instability in the climatic and geomorphological conditions in the region during the time when the sets of red layers in the desert were formed. We concluded that the release of iron from the primary minerals and their diffusion within the matrix of the geological material and its subsequent oxidation was the mechanism responsible for the dominant color of both the red layers and the paleosols of La Tatacoa desert.

Keywords : Paleosols; Synchronous variation; Pedogenesis; Macro and micromorphology; Lower red bed; Ferruginous bed; La Tatacoa desert, Huila, Colombia.

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