Sociedade & Natureza
On-line version ISSN 1982-4513
REZENDE, Éric Andrade et al. Lithological influence on rates of geochemical denudation in the middle Espinhaço Meridional - MG. Soc. nat. (Online) [online]. 2010, vol.22, n.3, pp. 503-514. ISSN 1982-4513. http://dx.doi.org/10.1590/S1982-45132010000300007.
This paper investigates the relationship between lithology and geochemical denudation rates in the middle Serra do Espinhaço Meridional. Denudation rates represent the volume of material from the alteration of rocks taken from a specified area at a known time period (Souch, 2004). These rates are strongly controlled by geological substrate, especially in less extensive watersheds. The method adopted is based on sampling of surface waters of sixteen sub-basins - that have low human interference and drain predominantly quartzite - and measuring the sampled channels flow. Chemical analysis of surface water collected in the humid and dry periods of the year were used to calculate geochemical denudation, which generally showed low in spite of the predominant rock resistance to weathering and denudational processes. The results showed that despite the relatively homogeneous lithology, the area does not hide the finding of a differential geochemical denudation, where: (i) basins that drain carbonate rocks have higher denudation rates, confirming the high solubility of this material, (ii) basins draining quartzite units show low denudation rates, especially the ones over the formations of Galho do Miguel and Sopa-Brumadinho.
Keywords : Chemical denudation; Serra do Espinhaço Meridional; Lithology.