Mid and late Holocene dust deposition in western Europe: the Misten peat bog (Hautes Fagnes – Belgium)

Abstract

Dust deposition in southern Belgium is estimated from the geochemical signature of an ombrotrophic peatland. The Rare Earth Elements (REE) and lithogenic elements concentrations, as well as Nd isotopes, were determined by HR-ICP-MS and MC-ICP-MS respectively, in along a ~6 m peat section covering 5300 yr, from 30 BC to 5300 BC dated by the ¹⁴C method. Changes in REE concentration in the peat correlate with those of Ti, Al, Sc and Zr that are lithogenic conservative elements, suggesting that REE are immobile in the studied peat bogs and can be used as tracers of dust deposition. Peat humification and testate amoebae were used to evaluate hydroclimatic conditions. The range of dust deposition varied from 0.03 to 4.0 g m^−2 yr^−1. The highest dust fluxes were observed from 800 to 600 BC and from 3200 to 2800 BC and correspond to cold periods. The εNd values show a large variability of −5 to −13, identifying three major sources of dusts: local soils, distal volcanic and desert particles

Periodic input of dust over the Eastern Carpathians during the Holocene linked with Saharan desertification and human impact

“…The dust flux delivered to an ombrotrophic bog via atmospheric loading may be calculated using the concentration of a lithogenic element, such as Ti (Allan et al, 2013). Using the averaged occurrence of Ti in the upper continental crust (upper continental crust (UCC) values from Wedepohl, 1995), the density of the peat, and the peat accumulation rate (PAR), the following formula may be used:…”

“…The link between atmospheric circulation patterns and dust input has been studied intensively (Allan et al, 2013;Kylander et al, 2013a;Marx et al, 2009;Le Roux et al, 2012) with clear evidence of climate variations linked with the dust cycle (Goudie and Middleton, 2006). Generally, dust is produced in arid zones (Grousset and Biscaye, 2005) and may be transported thousands of miles before deposition (Grousset et al, 2003).…”

“…1). As the only source of clastic material deposited within ombrotrophic bogs is via atmospheric loading, such records have been used convincingly as archives of dust deposition over the Holocene in western Europe and Australia (Allan et al, 2013;Kylander et al, 2013a;Marx et al, 2009Marx et al, , 2010Le Roux et al, 2012). To produce records of dust and/or hydroclimate variability, both inorganic (Allan et al, 2013;Ross-Barraclough and Shotyk, 2003; and organic (Booth et al, 2005;Lamentowicz et al, 2008;Morris et al, 2015;Swindles et al, 2010) proxies may be utilised (see Chambers et al, 2012) for a review).…”

Deciphering human–climate interactions in an ombrotrophic peat record: REE, Nd and Pb isotope signatures of dust supplies over the last 2500years (Misten bog, Belgium)

“…Here we focus on the upper 173 cm of peat, i.e., an ombrotrophic section (Allan et al, 2013c) that covers the past 2500 years (ages reported in Table 1). The Ca/Mg ratio and Sr concentrations were used to identify the ombrotrophic section as proposed by Shotyk et al (2001).…”

“…At the surface, where there are living Sphagnum mosses, the value (0.19) is close to the preanthropogenic value (0.28 lg g À1 ) measured at the base of the peat profile (753 cm, ca. 5500 BC, Allan et al, 2013c).…”