Navegando por Autor "Michel, Roberto Ferreira Machado"

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Soil-chronosequence and quaternary landscape evolution at the marine terraces of Harmony Point, Nelson Island, Maritime Antarctica.
(2022) Rodrigues, William Fortes; Machado, Mariana de Resende; Oliveira, Fábio Soares de; Schaefer, Carlos Ernesto Gonçalves Reynaud; Leite, Mariangela Garcia Praça; Michel, Roberto Ferreira Machado; Araújo, Teodoro Gauzzi Rodrigues de
This study characterized the physical, chemical, macro- and micromorphological soil properties from three successive marine terrace levels from Harmony Point (Nelson Island, Maritime Antarctica) in order to understand the pedological signatures of Quaternary coastal landscape evolution of Maritime Antarctica. Soils were sampled on the Late Holocene beach (current beach) and Mid Holocene marine terraces higher up, at 3, 8, and 12 m a.s.l. At the lower levels, the predominant soils were Gelorthents, whereas Haplogelepts dominate the higher terraces. Soil properties are mostly influenced by parent material and faunal activity, in which cryoclastic (thermal weathering) and phosphatization are the main soil-forming processes. Soils from the upper levels are more developed, deeper with reddish colors, granular structures and incipient formation B horizon. These horizonation features highlight that soils vary according with age of glacier-isostatic terrace uplift, representing a Quaternary soil chronosequence. All marine terrace levels are Ornithogenic soils, at varying degrees. However, the presence of old bird nesting sites for long periods led to formation of phosphatic horizons, stable Fe-phosphate minerals and abundant vegetation in the highest terraces of this part of Maritime Antarctica.