Geochemistry

ITRAXTM XRF Raw count per second (cps) data were analysed using the Q-spec software v8.6.0 (Cox Analytical), with MSE values minimised to optimise the fit of ''as measured'' spectra to a modelled spectrum. data are presented as percentages of the Total Scatter Normalised ratio sum (%TotalTSN or, more simply, %TSN, which are equivalent to percentages of the cps sum, or %cps) to account for downcore variations in count rate, density, water and organic content. Data less than mean minus two-sigma kcps (mainly due to gaps in the core) and greater than MSE plus two-sigma (representing a poor fit between measured to modelled spectra) were filtered before analysis. ''Noisy'' elements were eliminated by comparing cps and using%TSN thresholds of >0.1% mean and >0.5% maximum, and by examining autocorrelation profiles for each element (Bishop, 2021).This left 17 ''measurable'' elements for the LP16 record (Si , S, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Zn, As, Br, Rb, Sr, Zr , Ba, and inc., coh. scatter). Elements are presented as natural log (log n or Ln) ratios. Ti-normalised log n ratios are used to estimate changes in relation to the background bedrock input. Duplicates runs were undertaken on approx10% of the total core depth (LP16-3B at 200 and 500 microns).

Chronology

Radiocarbon ages were rounded to the nearest 10 calendar years (cal a BP) in file LP16_C14_data.csv and the results section and to the nearest 100 years (0.1 cal ka BP) in the discussion to reflect dating and age-depth modelling uncertainties.

Geochemical XRF-Core scanning data were measured at 500 micrometers for LP16 Units 2-6 (9.6±17.4 years) and at 200 micrometers for LP16 Unit 1 200 micrometers (1.1±1.6 years). Data from finely laminated glaciolacustrine sediments in Units 1-2 were measured at or smoothed to 200 micrometers (from 100 micrometers interval data) before analysis.