Denudation rates of the Southern Espinhaço Range, Minas Gerais, Brazil, determined by in situ-produced cosmogenic beryllium-10

Abstract

To investigate denudation rates in the southern part of the Espinhaço Range (central-eastern Brazil) and to understand how this important resistant and residual relief has evolved in the past 1.38 My, cosmogenic 10 Be concentrations produced in situ were measured in alluvial sediments from the three main regional basins, whose substratum is composed primarily of quartzites. The long-term denudation rates (up to 1.38 My) estimated from these measurements were compared with those that affect the western (São Francisco River) and eastern (Doce and Jequitinhonha Rivers) basins, which face the West San Francisco craton and the Atlantic, respectively. Denudation rates were measured in 27 samples collected in catchments of different sizes (6-970 km 2) and were compared with geomorphic parameters. The mean denudation rates determined in the northern part are low and similar to those determined in the southern part, despite slightly different geomorphic parameter values (catchment relief and mean slope). For the southern catchments, the values are 4.91 ± 1.01 m My −1 and 3.65 ± 1.26 m My − 1 for the Doce and São Francisco River basins, respectively; for the northern catchments, they are 4.40 ± 1.06 m My − 1 and 3.96 ± 0.91 m My − 1 for the Jequitinhonha and São Francisco River basins, respectively. These low values of denudation rates suggest no direct correlation if plotted against geomorphic parameters such as the catchment area, maximum elevation, catchment relief, average relief and mean slope gradients. These values show that the regional landscape evolves slowly and is strongly controlled by resistant lithology, with similar erosional rates in the three studied basins.

Denudation and retreat of the Serra do Mar escarpment in southern Brazil derived from in situ‐produced 10Be concentration in river sediment

“…The high erosional resistance of quartzite was also verified for other quartzitic reliefs in South America (Salgado et al, 2008;Barreto et al, 2013) for the denudation rates obtained by 10 Be cosmogenic nuclide concentrations. So the difference in the denudation rate values from both passive-margin of the South Atlantic seems to be controlled by the combination of lithologic, tectonic and climatic factors.…”

“…Furthermore, quartzite corps out in part of continental side of the Namibia escarpment and low denudation rates were verified for this area (around 0.5 mm ka -1 ) in comparison with the rates obtained for quartzite, granite and gneiss in the oceanic side of this escarpment (rates ranging between 2.3 and 15.2 mm ka -1 ; Cockburn et al, 2000). The high erosional resistance of quartzite was also verified for other quartzitic reliefs in South America (Salgado et al, 2008;Barreto et al, 2013) for the denudation rates obtained by 10 Be cosmogenic nuclide concentrations. So the difference in the denudation rate values from both passive-margin of the South Atlantic seems to be controlled by the combination of lithologic, tectonic and climatic factors.…”

Long-term erosion rates of Panamanian drainage basins determined using in situ 10 Be

“…Bolivia (Wittmann et al, 2009;Insel et al, 2010) is eroding faster than all other tropical sites and has the widest range in data. Basins in our dataset are eroding faster than those previously published for Panama (Nichols et al, 2005), as well as tropical sites in Australia (Heimsath et al, 2009;Nichols et al, 2014), Brazil (Salgado et al, 2006(Salgado et al, , 2007(Salgado et al, , 2008Cherem et al, 2012;Barreto et al, 2013Barreto et al, , 2014Rezende et al, 2013), Madagascar (Cox et al, 2009), Puerto Rico (Brown et al 1995(Brown et al , 1998Riebe et al, 2003), and Sri Lanka (Hewawasam et al, 2003;von Blanckenburg et al, 2004). Fig.…”

“…Contemporary sediment yield and cosmogenically-derived erosion rates for three of the rivers we studied are similar, suggesting that human activities are not increasing sediment yield above long-term erosion rate averages in Panama. , 2006Cherem et al, 2012;Barreto et al, 2013Barreto et al, , 2014; Rezende et al, …”

Vellozioid roots allow for habitat specialization among rock‐ and soil‐dwelling Velloziaceae in campos rupestres

“…only small amounts of micas or feldspars). In addition, compaction and metamorphism leads to a very restricted porosity and permeability (Aubrecht, Lánczos, Schlögl, & Filipčíková, ; Barreto et al, ; Salgado et al, ; Wray & Sauro, ). The success of vellozioid roots in these rocks is related to the increase in rock porosity through dissolution of the quartzite by roots between the rock bedding planes which leads to an increased moisture‐holding capacity.…”