Study of the erosion rates in the upper Maracujá Basin (Quadrilátero Ferrífero/MG, Brazil) by the in situ produced cosmogenic ¹⁰Be method

Abstract

The present work quantifies the erosive processes in the two main substrates (schists-phyllites and granites-gneisses) of the upper Maracujá Basin in the Quadrilátero Ferrífero/MG, Brazil, a region of semi-humid tropical climate. Two measuring methods of concentration were used: (i) in situ produced 10 Be in quartz veins (surface erosion rates) and (ii) 10 Be in fluvial sediments (basin erosion rates). The results confirm that (i) erosion tends to be more aggressive close to the headwaters than in the lower parts of the basin and (ii) the region is now affected by dissection. ConclusionThis work shows that the 10 Be method can be a very useful tool for geomorphological study in inter-tropical and intracratonic areas. This method does not differentiate between the role of geochemical and mechanical erosion and that of total erosion. However, the method has further application as a means of obtaining the measurement of quaternary erosion rates in hydrographic basins.The results show that the differential erosion between schists-phyllites and granites-gneisses-migmatites is not evident in the studied area, as claimed in previous works. The higher quaternary erosion rate in the upper portion basin, as well as the slope dissection process, constitute the main controls for the relief evolution of the Maracujá Basin. Erosion rates in the upper Maracujá Basin 911

Long-term background denudation rates of southern and southeastern Brazilian watersheds estimated with cosmogenic 10Be

“…Similarly, we found a relationship between precipitation and erosion at the regional scale in slope basins (Salgado et al, 2006(Salgado et al, , 2007. …”

“…Studies not included in Portenga and Bierman (2011), with data from tropical areas (such 10! as Puerto Rico, Africa, and Australia), include several from Brazil (Salgado et al, 2006(Salgado et al, , 2007(Salgado et al, , 11! 2008Cherem et al, 2012;Lal et al, 2012;Barreto et al, 2013Barreto et al, , 2014Hinderer et al, 12! 2013, Rezende et al, 2013, Brocard et al, 2014aNichols et al, 2014).…”

“…DR1. Watersheds sampled for Salgado et al 2006Salgado et al , 2007Salgado et al , 2008Salgado et al and 2013 publications. Watersheds are shown imposed over a Digital Elevation Model (DEM) background.…”

Eventos Deposicionais Fluviais Quaternários e Dinâmica Recente do Vale do Rio Maracujá – Quadrilátero Ferrífero/MG

“…Entretanto, estudos mais recentes desmistificam a correlação dessas superfícies com as mesmas cotas encontradas neste domínio, já que o controle litoestrutural e a erosão diferencial estão fortemente presentes no modelado regional (Varajão, 1991;Valadão, 1998;Salgado, 2006 (Chin, 1999;Duckson & Duckson, 2001;Bridge, 2003) e do próprio Quadrilátero Ferrífero . Com o encouraçamento da calha, o fluxo encontra uma barreira aos processos de incisão vertical, concentrando sua energia na migração lateral e conseqüente remoção da fácies argilosa superior e, no caso do médio curso superior, na própria erosão das vertentes, levando a um alargamento do vale.…”

Estudo da evolução da paisagem do quadrilátero ferrífero (Minas Gerais, Brasil) por meio da mensuração das taxas de erosão (10be) e da pedogênese

“…Posteriormente, Salgado et al (2007Salgado et al ( , 2008 chegaram a conclusões semelhantes utilizando como ferramenta o núcleo cosmogênico 10 Be, isótopo radioativo com meia-vida de 1,5 Ma, para mensurar, a longo termo (1,5 Ma), taxas médias de erosão de superfícies e de bacias hidrográficas (Brown et al, 1995;Granger et al, 1996;Blanckenburg, 2005 (Almeida, 1977). O clima da região é tropical semiúmido, possuindo duas estações climáticas bem definidas: verão úmido e inverno seco.…”