Table 1.

Overview of sample characterization by particle size analysis, Fe sequential extraction, elemental analysis (Al), and mineralogical analysis

SampleCore<8 µm*8–63 µm*>63 µm*FeHClFeHNO3AlQuartz§Feldspars§Clay minerals/micas§
vol%vol%vol%wt%wt%wt%wt%wt%wt%
Clay
C50I405730.420.269.630260
C125II6723100.680.378.721170
C150III94600.620.369.912079
Silt
S50I237250.280.888.1401936
S125II257140.180.373.4541325
S150III425600.290.996.4452128
Total
T50I3049210.390.888.2431336
T125II3141280.260.456.4471432
T150III3247210.481.146.7441235
  • *Particle size fractions in volume percentage coinciding with the clay-size fraction (<8 µm), the silt-size fraction (8–63 µm) and the sand-size fraction (>63 µm).

  • Fe extracted in a sequential extraction. FeHCL is FeII extracted by 1 m HCl (step 2 in Claff et al. 2010), which in these samples probably represents Fe from siderite. FeHNO3 is Fe extracted using concentrated HNO3 (step 5 in Claff et al. 2010) and represents Fe from pyrite.

  • Aluminium is measured by ICP-OES in a solution from sediment digested by HF, HNO3, HCl and HClO4.

  • §Weight percentages from semi-quantitative analysis of XRD spectra with an error of around 5 wt%.